UC Master Gardeners, Santa Clara County, CA
University of California
UC Master Gardeners, Santa Clara County, CA

January Tips

Garden Help > Monthly Tips

Monthly tips are categorized by To-Dos, What to Plant, or Pests and Diseases. Scroll through the list to see items in each category. Also, refer to our list of tips useful for any month.

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1. To-do

  • Citrus Fertilizing -

    Honey bee on citrus blossom
    Honey bee on citrus blossom
    In California, most soils contain adequate nutrients for citrus growth, except nitrogen. Nitrogen is the primary nutrient required by the trees, and there are commercial fertilizers balanced specifically for citrus. One-year-old trees will need 1/10 of a pound of nitrogen, while mature trees need approximately 1-1/2 pounds. These amounts should be divided into two to three applications.

    Blood meal without all the fillers is an excellent source of nitrogen, or you can purchase a balanced product that contains zinc. Spread the fertilizer evenly over the entire root area and water in.

    For more information, refer to the UC Pest Note on Fertilizing Citrus, and Questions and Answers to Citrus Management from the UC Davis Home Orchard website.

    - January, February, May, June
  • Save the Worms -

    Worms aerate the soil with their tunneling, break down organic material such as fallen leaves and make the nutrients available to plants, and they excrete nice rich fertilizer in the process. They help create a sustainable system in your garden and do a lot of your garden chores for you. If you see them on the sidewalk during heavy rains, rescue them and take them to a safe place in your yard.

    - January, February
  • Weed Management -

    Photo: Oxalis pes-caprae aka Bermuda buttercup, by Joseph DiTomaso, UC ANR
    Photo: Oxalis pes-caprae aka Bermuda buttercup, by Joseph DiTomaso, UC ANR
    While some weeds are edible (purslane, nettles, dandelions, miner's lettuce), many are a nuisance and compete with your chosen plants for water and nutrients.

    Whichever variation of “One year’s seeds makes seven years’ weeds” you prefer, the truth remains: a key part of weed control is not letting them go to seed. For best results, work on removing weeds before they are able to propagate. Hand pulling and hoeing are effective methods for killing many common weeds.
    Knowing what kind of weeds you have and how it propagates can be helpful in choosing the best management method. If they propagate by seed, pull or hoe them before they flower and go to seed. If they re-grow from roots, pull up as much of the root as possible. Many weeds, like Bermuda grass, have multiple ways of multiplying. Only non-propagating parts are advisable to throw in the compost bin.
    - January, February, March, Any month
  • Dormant Rose Pruning -

    Rose 'Pink Pillar'
    Rose 'Pink Pillar'
    Winter is the best time to prune roses even if they haven’t gone completely dormant. The old advice was to cut the canes down drastically, but that isn’t necessary for our climate. Instead, just cut back about one-third to one-half of the total height. In other words, take a 4-foot bush down to about 2–3 feet. When cutting back a cane, make the cut at an angle just above an outward pointing bud. Take out any dead or diseased canes, remove suckers below the graft union, and branches that are crossing or growing towards the middle of the plant to improve airflow. Clean up old leaves on the plant and ground to reduce rust and black spot.

    More Information: Rose Care

    - January, February, December
  • Winter Irrigation -

    Depending on the fall weather and rain frequency, you will likely set your sprinklers to water less frequently or even turn them off for a while. It's still important to check outdoor plants to ensure they have enough water. While they need less water when it's cool, it's important to make sure they don't dry out. If you have a lawn and rains haven't come, irrigate the lawn once or twice this month.

    If it has been raining, the soil may be saturated, so be careful if you have to walk on it to not compact it. Also, if the soil is waterlogged, vital space for air needed for plants and worms, and excess water can drown beneficial soil organisms and contribute to rotting roots.

    - January, February, December
  • Recycle Holiday Plants -

    If you have a Christmas tree to recycle, please follow the procedure for your local community program so that the trees can be recycled into compost or materials.  Insects and diseases which may be on the cut trees could escape and spread if the trees were used as mulch in homeowners' yards.

    Other popular holiday plants such as poinsettias, azaleas, or cyclamen can also be recycled. Remove the foil wrapping off the containers (for better drainage) and put the outdoor plants somewhere sheltered until you can plant them. The heated air in your home will dry out both these outdoor plants as well as your indoor plants. You may want to check those indoor plants too.

    - January
  • Stake Your Brassicas -

    Your Brussels sprouts and other brassicas may collapse with the weight of the rain. Tying them to a three-foot stake will maximize your chances for a better crop. If you're noticing yellow flowers on your broccoli already, the cold-then-warm temperatures have caused them to bolt; you can try new plants or start thinking ahead to your warm weather garden.

    - January
  • Yellow Leaves on Citrus Trees -

    Yellow leaves on citrus Help Desk submission
    While there are several possible causes for yellow citrus leaves, the most likely one in winter/early spring is that citrus roots do not absorb nitrogen efficiently from cold, wet soils. There may be adequate nitrogen in the soil, but the roots aren’t able to take it up. However, if the tree doesn’t green up when the weather warms, give it some nitrogen fertilizer, up to 1 lb of N per year for a mature, full-size tree. Dwarf trees or ones in containers require less fertilizer, 1/2 lb of N or less. Do not overfertilize since that may cause other problems.

    More information: Growing Great Citrus


    - January, February, March, April
  • Leafy Salad Plants -

    Lettuce by Donna Lee
    Harvest your leafy vegetables early and often. Many leafy vegetables will bolt (go to flower) quickly if not harvested. When you harvest lettuce or similar greens, remove only the outer, older leaves. New leaves will continue to grow from the center, and you'll be able to eat salads all winter. Harvest head lettuce all at once when the head is full and firm. Watch for signs that plants are getting ready to bolt. That’s the signal it’s time to harvest the entire plant.

    - January, February, March, November, December
  • Perennials and Bunch Grasses -
    Winter is a good time to cut back perennials and bunch grasses. You can cut back some perennials all the way to the ground. These include yarrow, hummingbird sage, goldenrod, California aster, and most kinds of California fuchsia. You can divide other perennials at this time, such as Douglas iris, alum root, seaside daisy, woodland and beach strawberry, yarrow, yerba buena, daylilies, and chrysanthemums.
    You can propagate bunch grasses, sedges, and rushes by division this time of year. Examples of bunch grasses are purple needle grass (state grass of California), fescues, blue grama, leafy reed, oat, and deer grass. Some sedges are the meadow, clustered field, and San Diego sedge. Rushes include the common rush and the California gray rush.
    - January, February, December
  • Mushrooms -

    Sometimes it seems like there are mushrooms all over: mushrooms in the lawn; mushrooms on the trees; mushrooms in fertilizer; mushrooms in the woods; there is even mushroom compost available. How do you know which mushrooms are desirable and which are not? This can be a life or death determination, both for you and for your plants. Mushrooms are the fruiting bodies we see of fungi which can be widespread and hidden underground or inside plants. Fungi play a beneficial role in decomposition and in providing nutrients to garden plants. Mushrooms in the lawn can be a sign of overwatering, so check the irrigation and drainage. You don't need to remove the mushrooms except to protect young children and pets from eating them. If cultivating or harvesting mushrooms to eat, be sure that you know it is not a poisonous variety.     

    More information: Mushrooms in lawns
    - January, February, December
  • Houseplants Repotting -

    Snake plant (Dracaena trifasciata) in need of repotting, Allen Buchinski
    If you’ve noticed the soil in your houseplants is drying out quickly, or leaves are turning yellow, check whether the plant is rootbound. The most obvious clue is roots growing from a drainage hole or on top of the soil. Especially vigorous roots can break pots! UC scientists recommend choosing a new container no more than 2 inches larger in diameter, with drainage holes. Don’t add stones to the bottom – they hinder drainage, causing root rot. Use new potting soil, not garden soil that may harbor diseases or pests. Unwind and trim roots that circle the pot. Add soil to the container, keep the root ball an inch below the rim, and water well.

    More information:  Repotting Houseplants

    - January, February, December, Any month
  • Harvesting Oranges -

    Valencia Oranges (top) with grafted Kishu Mandarin (below)
    Valencia Oranges (top) with grafted Kishu Mandarin (below)
    There’s a simple way to know whether your citrus fruit is ripe: taste it! Citrus varieties differ in when they first ripen and how long the fruit holds on the tree. Harvest dates depend on the variety and the climate. For example, the normal fruit season is winter for Navel orange, and summer for Valencia orange. Until you are familiar with your particular tree, sample a fruit periodically to see if it suits your taste. Allow fruit to ripen fully on the tree, as citrus does not continue to ripen once it’s picked. 

    More information: Harvesting and storing citrus

    - January, February, July, August, September, October, November
  • Fruit Tree Pruning -

    Dormant branch pruning, UC
    Winter is the best time to prune most deciduous fruit trees because the tree structure is easily seen once the leaves drop. Start by removing crossing branches, broken branches, and diseased wood. Clean out suckers, and light branches. Trim the branches that grow vertically. Then make cuts to produce the desired height and shape and to allow sunlight into the center of the tree. Not sure about the shape? UC has more information in Publication 8057, Fruit Trees: Training and Pruning Deciduous Trees. View a pruning video using the link below or refer to Fruit Tree Pruning.

    If you properly prune and care for fruit trees you will get the highest yield of fruit. A good rule of thumb is to prune plum, pluot, apple, and pear trees 15-20%; and peaches 50%.
    A reminder: since apricot and cherry trees are susceptible to Eutypa fungus, they should be pruned in late summer to allow pruning cuts to harden before winter rain.
    - January, February, December
  • Pruning Tools Maintenance -

    Pruning tools: saw, loppers, and hand pruners, by Allen Buchinski
    Remember to keep your pruners and loppers clean and sharp. Read our tool care tips webpage for advice about cleaning, sharpening, and sterilizing your tools.

    - January, February, December, Any month
  • Frost Dates -

    The approximate first and last frost dates for Santa Clara County, depending on your location, are November 15 and March 15. These are important dates for gardeners to remember.

    First frost date—this is the earliest date you should expect frost to occur. If you have plants that need to be brought in for the winter, or crops you need to pick before frost, this date will be important to you.

    Last frost date—after this date, you wouldn't expect any more frosts. It's generally used as a milestone when pruning frost-sensitive plants (such as citrus where you don't want to stimulate delicate new growth until the danger of frost is past).

    For our climate, the last frost date is not a reliable metric for when to transplant summer vegetables. Daytime temperatures and soil temperatures are more important. See entries for individual vegetables for specific recommendations.

    Also see: Frost—Avoidance and Dealing with Damage

    - January, February, March, November, December
  • Prune Apple Trees -

    Once your apple tree loses its leaves, it's time to think about pruning. Apple trees produce fruit terminally on spurs located on wood 2 yrs. to 8 yrs. old. Weak and unproductive branches should be thinned out to allow the sunlight into the tree for good spur development. Older spurs can be rejuvenated by cutting back, especially following a light crop year. Tree height is maintained by cutting back upper branches to shorter laterals. Excessive pruning of a bearing tree can negatively affect its vigor and fruit. Consult our Fruit Tree Pruning page for more information.

    - January, February, December
  • New Trees Staking -

    Proper tree staking and planting, UC Landscape Horticulture Blog
    Proper tree staking and planting, UC Landscape Horticulture Blog
    Not all new trees even need to be staked. Only stake if necessary for protection, anchorage, or support. Don't place the stakes too close to the trunk of the tree. Place stakes on opposite sides of the tree, outside the root ball. Make sure the stakes don’t rub on the trunk or branches. Ties should be added no higher than necessary to support the trunk. This allows as much freedom to move as possible, and movement builds trunk strength. Inspect the tree regularly to make sure there’s no damage. Remove the ties and stakes when the tree can stand on its own, generally after a year or so.

    More Information: Tree Staking
    - January, February, March, April
  • Chill Hours -
    Many fruit varieties require a certain amount of winter cold, measured in chill hours, in order to produce a good crop. Since we can’t change the weather, it’s important to select new fruit trees by considering their chill hour requirements. Here are UC suggestions for varieties of apple, pear, peach, nectarine, plums, and kiwifruit for planting in home gardens.
    UC has historical chill hours available for many locations in California, Gilroy is the only location located in Santa Clara County.
    - January, February, December
  • Controlling Bermudagrass -

    Bermudagrass (Cynodon dactylon) Photo by Jack Kelly Clark.
    Bermudagrass is a warm season grass, going dormant in winter, so that's not the best time of year to fight it. Spraying it in winter won't work because it can't take up the poison since it is not actively growing. But you can install sheet mulching to smother spring/summer growth, or dig out roots if the soil is not too wet. For more information, read the UC Pest Note on Bermudagrass.

    - January
  • Why You Should Test Your Soil -

    Before adding fertilizer or soil amendments to your garden, first find out what your soil really needs by conducting a soil test. Knowing your soil’s pH value is important in determining which plants will thrive or struggle in your soil. Understanding the levels of nitrogen, phosphorous, and potassium in your soil will tell you which nutrients are abundant and which are lacking. Don’t overfertilize – excess nutrients can pollute local waterways. Commercial soil testing labs provide the most thorough results, but several home kits can give you a good baseline. Test soon and be ready for spring planting.

    - January, February, March
  • Bolting Lettuces -

    In garden terms, bolting means sending up a flower stalk, not desirable unless you plan to save seeds. Seed packets say lettuce matures in 60–80 days, but the timing also depends on the weather. In warm weather, lettuce matures and bolts much faster. In cool temperatures, seedlings grow more slowly but will still mature and bolt eventually. If the center of the lettuce starts to push upwards, that’s a clue that it’s starting to bolt. Another clue is if you tear a leaf and see milky sap instead of clear juices. Harvest as soon as you notice, before the leaves become unpleasantly bitter.

    More information: Growing Lettuce

    - January, February, March, November, December
  • Pruning California Natives -

    If your landscape includes California native plants, you may wonder if you should prune them. It depends. Some don’t respond well to shaping or shearing to control size. But they do like careful pruning at the proper time, which is when they are dormant. That could be either summer or mid-winter. Natives that do well with winter trimming include California buckeye (Aesculus californica), honeysuckle (Lonicera hispidula), and salvia species. California fuchsia (Epilobium canum) and lilac verbena (Verbena lilacina) can be cut almost to the ground. But wait until summer for grasses and broadleaf evergreen shrubs and trees.

    More information: How to Prune California Native Plants

    - January, February
  • Dormant Season Berry Pruning -

    Parts of a raspberry plant, University of Minnesota Extension
    Parts of a raspberry plant, University of Minnesota Extension
    The time of year to cut back raspberry canes depends on the type of raspberry you’re growing. For summer-bearing varieties, remove all the floricanes that bore fruit immediately after the summer harvest, leaving the new green primocanes. Then, in the winter, you can just inspect and remove any weak or damaged canes. For fall-bearing (also called everbearing) varieties, you have a choice. Canes that bore fruit in the fall will produce a small crop in the summer, then can be cut down. Or, to skip the summer crop in favor of a heavier fall crop, you can cut down all growth in the winter to encourage vigorous summer growth.

    More Information: Blackberries and Raspberries

    - January
  • Fruit Tree Grafting -

    When pruning dormant fruit trees, you may want to save cuttings (scions) for later grafting onto other fruit trees. Grafting is a technique that allows you to have multiple varieties of compatible fruit on one tree and is a great space saver. It works by joining the vascular tissues of a shoot (scion) from one tree to a different tree that provides the root system. If the graft is successful, the scion will continue to grow and maintain the characteristics and fruit of the scion plant. Fruit trees can have new varieties grafted to them when they are dormant in January and February.

    Scions are available in January or February at the California Rare Fruit Growers (CRFG scion exchange). Their January event also includes training classes. Check the CRFG - Santa Clara blog for the date.

    More information on grafting can be found at:

    - January, February, December
  • Flowering Vines -

    Vines are plants that climb or sprawl and can easily outgrow their spaces if not pruned annually or more often. Many are pruned in the winter when they are dormant. This reduces shock to the plant and allows you to better see the structure when pruning. If the vines are flowering, wait until after the blooms have finished. Some vines get cut back almost to the ground to renew them. Some are cut back to the beginning of the herbaceous growth, leaving the woody vines. Others are pruned simply for shape or size. The UC Davis Arboretum All-Stars brochure includes several flowering vines. All-Stars are plants that have been tested and proven to thrive in California. The brochure lists pruning needs. It also has photos, characteristics, and requirements of the plants if you are looking for new plants.  

    - January, February, March
  • Certified Arborists -
    Whether you prune your own trees or hire someone, it’s important that whoever does the job knows at least a little about tree anatomy, plant health, and the purpose of the plant (shade? privacy? fruit?). Knowing the difference between heading cuts and thinning cuts, how to locate a node to direct growth, and how to open up a tree for air circulation are all part of good tree pruning. An improper pruning job can stress the tree, spread disease, invite pests, and promote weak branching. These can lead to breakage, damage, and injury. The cheapest bid may end up costing more in the long run due to damage repair, lawsuits, and additional fix-it pruning. Take a class or read tree pruning guides if you want to do a good job yourself. If you hire someone, it is strongly recommended that you choose a certified arborist who has been specially trained and is insured. The International Society of Arboriculture can help you find a certified arborist in your area.
    More Information: Tree Pruning Guide
    - January, February, March, December
  • Stinkhorn Mushroom -

    Clockwise from upper left: Tom Volk, Ted Geibel, Troy Bartlett, and Gloria Schoenholtz. From the University of Wisconsin-Madison Division of Extension
    Clockwise from upper left: Tom Volk, Ted Geibel, Troy Bartlett, and Gloria Schoenholtz. From the University of Wisconsin-Madison Division of Extension
    You might find stinkhorn mushrooms growing out of a lawn or a pile of mulch. They come in many colors, shapes, and sizes. They can grow as fast as four to six inches per hour. Stinkhorns get their name from their foul odor, described by some people as a rotting meat smell. The smell attracts insects, which then spread the mushroom spores. While the smell is unappealing, stinkhorns are short-lived, and they help break down organic matter into the soil. They are most likely to appear in cool, wet weather. UC has management advice for mushrooms and other nuisance fungi in lawns.

    More information:  Stinkhorn Mushroom



    - January, February, March, October, November, December

2. What to plant

  • Fresh Cut Flowers from Your Garden -

    Fragrant sweet peas, Barbara Krause
    We have a webpage to help you choose and grow beautiful cut flowers for your home or to give away. The Cut Flower Planting Chart lists ornamentals we’ve grown successfully. We selected these for their hardiness, appeal to pollinators, and production of good cutting flowers. The chart tells you when to start these flowers from seeds or when to transplant, plus when you can expect to see blossoms. 

    More information: Tips on planting a cut flower garden

    - January, February, March, April, May, June, Any month
  • Selecting Seeds -

    While curled up inside the warm, dry house poring through seed catalogs, how do you decide among all the delightful descriptions? First, be clear on the purpose of your garden. Are you trying to grow exotic food? Do you want to attract native butterflies? Are you interested in flowers you can cut and bring inside? Next, think about the conditions of your site. Is it warm and sunny or is there a lot of shade? Do you have heavy clay soil? Choosing seeds that do well in your area makes for healthier plants with less work. At this point, you have the parameters within which to choose what tickles your fancy. If you would like to save seeds in the future, then choose open-pollinated seeds, including heirlooms. Heirlooms are open-pollinated seeds that have been around for multiple generations. Otherwise, you can plant hybrids that have the best traits of their parent plants but will not reproduce true to type from saved seeds. Follow planting directions on the packet for the best results.

    More Information: Seed Saving
    - January, February, March, May, June, July, August, October
  • Plant Asparagus Crowns -

    Asparagus crowns can be planted now. Dig a trench eight to twelve inches deep, mix in fertilizer at the bottom and cover with two inches of soil. Set the roots in the trench about 18 inches apart, and cover with two inches of soil. Gradually fill in the trench as the plants start to grow. Asparagus is a perennial vegetable that will produce for several years. It's best to wait until the second year to harvest to let a strong root system develop for long term production. For more information, read UC Davis' Growing Asparagus in the Garden.

    - January, February, March
  • California Natives -

    Master Gardeners’ Berger Native Demonstration Garden, by Rebecca Schoenenberger
    Thinking of adding native California plants to your yard? New natives respond best to wet winter weather, which promotes the extensive root development needed for spring growth and the hot dry summer months ahead. Your next question may be what to plant. That depends on your planting site and the individual cultural requirements of the plant. To help, the California Native Plant Society has created a database where you can enter your address and find which plants do best in your neighborhood for the conditions in your yard, like sun or shade. The website even lists nurseries that carry California natives.

    More Information:
    - January, February, March, December
  • Seed Viability -

    Seed packets have a “packed for” date on the back. Yet seeds can still be viable for years beyond that date if stored correctly. Ideal storage conditions are cool and dry. The older the seeds are, the lower the germination rate will be. So plant more of the older seeds than the number of plants you ultimately want. You can do a germination test by putting seeds on a damp paper towel and enclosing them in plastic to keep them uniformly moist. Do this right before planting time so you can transplant the ones that successfully germinate. Or you can take your chances and just plant them directly and see what comes up. If you are saving your own seeds, make sure to choose seeds from the healthiest plants.

    Whenever it's hard to find flower seedlings, if you have some old flower seed packets, you can scatter the seeds randomly in a section of your yard and enjoy whatever flowers.

    More Information: Vegetable Seed Viability
    - January, February, March, April, May, August, September, October
  • Camellias -

    Camellia japonica ´Professor Charles S. Sargent’, by Barbara H. Smith, Clemson Extension
    Camellias can be planted in fall through spring. Since they bloom in winter, choosing a plant now will ensure that you know the color, shape, and size of the flowers with which you will live for many years. Camellias are not native to our area so may need some extra attention in order to grow successfully. Our native clay soil does not drain well so it must be amended for camellias. Our alkaline soil needs to be acidified, and sulfur pellets are one way to achieve this. The plants need some shade and need to be kept moist. Mulch helps hold in moisture, and pine needles, redwood bark, and coffee grounds are all good organic materials that will break down over time and help improve the soil. Pick up flowers as soon as they fall to the ground to avoid the spreading of a disease called Camellia petal blight. 

    More information: Camellia Pests

    - January, February, March, April, May, September, October, November, December
  • Bare Root Roses -
    January and February are ideal for planting bare root roses. When you choose roses, the American Rose Society can help you navigate the 150 species and thousands of hybrids. Besides color and growth form, you may also consider the balance between scent and appearance. Many of the older roses are highly fragrant, while many newer roses are bred for beauty and large blooms. Consider the susceptibility of roses to many diseases when choosing a spot in your garden. They do best with six hours of sun, in well-drained soil, with good air circulation, and without overhead watering. When planting, mix organic material with native soil in the planting hole. Make sure the base of the plant remains an inch or two above the surrounding soil so that water doesn’t accumulate around the crown. Water thoroughly immediately after planting.  
    - January, February
  • Plant Native Shrubs and Flowers -

    Native shrubs like manzanitas, silk tassel bush, and currants come into bloom and provide nourishment for wildlife at the height of winter. These carefree, water-wise shrubs look good throughout the year.

    Winter is still a good time to plant native plants. It is not too late to scatter wildflower seeds like California poppy, mountain garland, baby blue eyes, globe or bird's eye gilia, clarkias, lupines and tidy tips. Make sure the seeds have good soil contact by walking or tamping on the seeded areas. Consider planting native bulbs like wild hyacinth, mariposa lily, harvest brodiaea or soap plant in areas that remain dry through the summer, perhaps at the feet of established shrubs.

    If you've had California poppies before, they'll start popping up all around as a result of winter rains. If you're interested in brilliant orange spring color, you can still scatter seeds now. When choosing a spot to plant them, keep in mind that they re-seed themselves readily and they can smother nearby small plants.

    - January
  • Bare Root Plants -

    Bare-root tree planting, by Chuck Ingels, UC
    Bare root plants are sold without any soil clinging to the roots making them easier and less expensive to transport; they'll do just fine in the garden as long as you don't let them dry out before planting. Because you can see the roots and can control how they're placed in the soil, it helps reduce the chances of root girdling problems later. Buy and plant early in the month while roots are still fresh.

    The bare roots should be soaked from an hour to overnight (large plants) in a bucket of water before planting. Trim roots of broken, dead, or spongy bits and carefully pull the roots apart. Dig a hole that is fairly shallow and wide. Spread the roots out sideways and have the crown of the plant several inches above the soil level. This is necessary as the plant will settle down over time. Water in well but wait to fertilize until you see new shoots growing. Be sure to water regularly if the rains are sparse. Staking may not be necessary.

    Trees aren't the only plants that are sold bare root. You can also plant bare-root asparagus, artichokes, rhubarb, berries, kiwifruit, horseradish, rhubarb, grapes, roses, strawberries, and iris in January.

    More information: Planting Bare-Root Fruit Trees

    - January, February, March
  • Poinsettias -

    Poinsettias are tropical plants, so they'll do best in a warm, sunny place in your house. The soil can easily dry out and become hydrophobic, so make sure to check the soil moisture regularly. There’s really no need to fuss over them if you’re only keeping them for a few weeks of holiday color. If you want them to bloom again next year in time for the holidays, UC has Poinsettia Care Tips that describe what to do; just be aware that it is a little tricky.

    Did you know that the red parts are actually bracts (modified leaves) and that the true flowers are the little yellow parts in the centers? You can also plant them outdoors with protection from frost. They have been seen growing as tall as eight feet in San Jose, and taller in their native Mexico.

    - January, December
  • Amaryllis or is it Hippeastrum? -

    Brighten the holidays with Amaryllis (Photo: UC Solano Master Gardeners)
    Brighten the holidays with Amaryllis (Photo: UC Solano Master Gardeners)
    The showy red Amaryllis (more correctly called Hippeastrum) is a great bulb for growing indoors if you can’t wait for your outdoor bulbs to bloom in spring. Choose a pot just slightly larger than the bulb. Plant it in loose potting soil with a third of the bulb sticking up above the soil surface. Keep moist, but not so wet as to rot the bulb. The University of Minnesota Extension has information on general care and how to control blooming.

    - January, December

3. Pests and Diseases

  • Limes -

    Blossom End Rot on a Bearss Lime
    Blossom End Rot on a Bearss Lime
    Limes are easy to grow in our area and make a pretty addition to the landscape. They don’t take up as much space as some other citrus and can grow well in our native soil with plenty of sun. They need some fertilizing and occasional protection from the cold. Bearss Lime is a popular variety that has fruit ripening now. Other favorites include Mexican Lime, Australian Finger Lime, and a Limequat hybrid. Most limes are yellow when fully ripe and have a higher juice content at this stage; most limes in stores are green because they have a longer post-harvest life or shelf life. A tan, leathery sunken area at the end of the fruit is called blossom end rot in citrus. It can come from insufficient water, preventing calcium from getting all the way to the ends of the fruit (similar to blossom end rot in tomatoes.) You can freeze the fruits whole for year-round margaritas or whatever it is you do with your limes. Freezing weakens the cell walls, which makes it even easier to juice the limes after thawing.

    More Information: Growing Citrus Fruits

    - January, November, December
  • Snails and Slugs -

    Beer trap for snails and slugs, UC, by Jack Kelly Clark
    Escargot may sound good on a plate, which is where the French who brought this delicacy to California in the 1850s intended for the ingredients to stay, but they escaped into gardens where they became pests. Brown garden snails are the most common ones we see (or don’t see) eating our plants. Signs of their presence include holes in fruit rinds and leaves, not necessarily at the edges, and slime trails. They tend to hide in dark damp places during the day and come out mostly at night. The best times to find them are at night with a flashlight, early in the morning, or during and right after heavy rain. They can be hand-picked and crushed or put in a bucket of soapy water. Gloves are recommended, especially with the shell-less slugs. Creating hiding places, such as laying a wooden board over a section of the garden, will draw them to that location so you can find and dispatch them in the morning. Copper barriers and beer traps are other options. If you do use snail bait, those made with iron phosphate are not toxic to pets and wildlife.

    More information: Snails and Slugs

    - January, February, March, April, December
  • Rat Management -

    Rat damaged orange
    Have you found a hollowed-out orange or other sour fruit like Meyer lemons with no skins, tomatoes with bite marks, fruit with holes gnawed in them, or grape skins or cherry tomato skins scattered around? It is the work of a roof rat. 

    Rats show up when your citrus, tomato, or fruit first starts to ripen. Rats are agile climbers and usually live and nest in shrubs, trees, and dense ground cover like ivy. One management strategy is to prevent access to the tree by cutting branches away from fences or other trees, leaving a gap of at least 2–3 feet, good sanitation is required. Garbage and garden debris should be eliminated. Use tight-fitting lids on garbage cans. Thin out dense vegetation to make the habitat less desirable. Mow ivy once a year to the ground. Climbing ivies on fences or buildings should be removed.

    Per the UC pest note (linked below), trapping is the safest and easiest method for controlling rats. Read the pest note for other management strategies as well.

    More information: Rat Management

    - January, February, March, April, July, August, September, Any month
  • Control Insect Pests with Horticultural Oil -

    Spray apple, pear, peach and nectarine, apricot trees with horticultural oil during the dormant period to control scale, and aphid and mite eggs. For more information on using horticultural oil to control pests consult:
    - UC Pest Note on Scales
    UC Pest Note on Aphids
    - UC Pest Note on Spider Mites

    - January
  • Don't Move Firewood -

    Don't move firewood logo from https://www.dontmovefirewood.org
    Tree-killing insects and diseases can lurk in or on firewood. These insects and diseases can’t move far on their own, but when people move firewood, these pests can jump hundreds of miles. Beetles that have done significant damage in Southern California are the Goldspotted Oak Borer and Invasive Shot Hole Borers. Let’s keep them out of Santa Clara County.

    - January, December
  • Dormant Oil Spraying -

    San Jose Scale
    San Jose Scale
    Deciduous fruit trees lose their leaves seasonally, usually in the autumn. They enter a period of dormancy when they are not actively growing and there is little activity within the plant. This is the time to apply dormant oil sprays to smother soft-bodied insects such as scale, aphids, and mites. First, do any needed pruning so that you will not be spraying branches that will soon be removed. Then inspect for pests that are overwintering on the trees, or remember pest and disease problems you noticed during the growing season. Although dormant oils may count as organic, it is still best to use them only if pest problems have been observed. 

    Mix the horticultural oil in a sprayer and apply it according to directions on the packaging. Never use more than what is prescribed. Make sure to complete the spraying before the trees start to bud and blossom so as not to damage developing flowers and fruit.
    - January, February, March
  • Armillaria Root Rot -

    Mushrooms at the base of a tree could signal a problem with the tree. Armillaria is a fungus that can live in the soil for many years. It can rot the roots and cause leaves and branches to die and can eventually kill a plant. Another common term is Oak Root Fungus, although it affects many different species of trees and even some herbaceous plants. Often by the time the fruiting bodies (mushrooms) are visible, much damage has already been done. It feeds on both live and decaying wood. Cutting back a small section of bark can reveal white fan-shaped or black stringy fungus which aids in diagnosis. Keeping the plant healthy provides some defense. Fungi thrive in moist conditions, so do not overwater the area. Also, keep mulch and other plants away from the trunks of trees so as not to hold moisture against the crown (base). The best defense against this disease is to plant resistant varieties.

    For information: Armillaria Root Rot

    - January, February, December
  • Slime Molds -

    A slime mold on a compost pile, also known as “dog vomit slime mold”, Help Desk submission
    A slime mold on a compost pile, also known as “dog vomit slime mold”, Help Desk submission
    Slime molds come in a variety of colors and shapes. They often appear suddenly and look worrisome. They are fungi and need moisture to grow. According to the Mississippi State Extension, “when slime molds find something to eat, they surround their food and then swallow it. Slime molds may feed indirectly on dissolved substances escaping from organic matter, but they usually feed on microorganisms such as bacteria.” In general, no action is needed. When the area dries out, the slime mold will disappear. Just enjoy this marvel of nature while it’s there.


    - January, February, March, April, October, November, December
  • Citrus Leafminer -

    What causes young, healthy citrus leaves to become gnarled and disfigured and what can be done about it? This damage is due to the citrus leafminer moth that lays eggs on new citrus leaves. Its larvae burrow into the leaf and leave tunnels as they feed, visible as meandering serpentine mines. Our advice: don’t worry about it. Leafminers can slow the growth of young trees but even heavily damaged trees are unlikely to die. Leafminers only attack young leaves — the tough leaves of mature plants resist infestation and fruit is not affected. Damaged leaves still produce food for the tree, so don’t cut them off. If you do, it will stimulate the tree to produce more new leaves — which will attract more leafminers!

    More information: Citrus Leafminer

    - January, February, March, April, May, September, October, November, December

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