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

January 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.

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
  • 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 make sure 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 so as not to compact it.  Also if soil is waterlogged, vital space for air that is needed for plants and worms and excess water can drown beneficial soil organisms and contributed 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
  • Pruning Roses to Minimize Disease -

    A chemical-free way to keep roses healthy and minimize disease associated with foggy summer mornings is to prune to improve air circulation.

    Roses pruning photo from University of Illinois
    Make sure you wear gloves to protect your hands from thorns and use clean, sharp tools. First, remove dead and diseased parts. Then remove anything that is growing where it doesn’t belong. This includes suckers below the graft union and branches that are crossing or growing towards the middle of the plant. Finally, prune for shape and health. Cut back to about four or five evenly-spaced strong canes, leaving a few buds on each cane. Make pruning cuts ¼ inch above outward-facing buds in order to create a vase shape that allows for good air circulation. Good air circulation allows the morning dew to dry and helps prevent rust and powdery mildew. 

    More Information: Rose Pruning

    - January, February, March, April, December
  • Leafy Salad Plants -
    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 long. Harvest head lettuce all at once when the head is full and firm.
     
     
    - 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
  • Frost Dates -

    The first and last frost dates for Santa Clara County are November 15 and March 15. These are important—but approximate—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 planting outdoors, or pruning frost sensitive plants (such as citrus where you don't want to stimulate delicate new growth until danger of frost is past).

     

     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
  • Winter Fruit Tree Pruning -

    Pruning Tools – Keep them clean and sharp

    Remember to keep your pruners and loppers sharp. Good pruners use bypass blades rather than anvil type. Anvils have only one cutting blade and one flat blade which can result in "smashing" the plant material. Sterilize the pruners or loppers between each plant and after cutting off any diseased plant material. Use a 10% bleach solution (1 part bleach, 9 parts water) or disinfectant bathroom cleaner.

    What and When to prune

    According to UC's Backyard Orchard website, "the optimum time of year to prune fruit trees is the dormant season, December, January (best) and until the middle of February." Apricots are the exception for pruning in January; they should be pruned in the summer after harvest. 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%.

    January is also a good time to prune roses. A basic guide is to keep 3-6 strong, healthy, outside canes per plant and leave 3-5 buds on each cane. Cut on the diagonal ¼ inch above an outward-facing bud. More information is available at UC Pest Note on Roses: Cultural Practices. The San Jose Heritage Rose Garden offers free hands-on pruning classes every Saturday in January and February.

    Deciduous trees can be pruned anytime during their dormant season (in winter). Prune deciduous species, such as Western spice bush, creek dogwood, Western mock orange, red-bud, maples and deciduous oaks.

    Do not prune apricot and cherry trees in winter because they are susceptible to Eutypa dieback. The best time to prune them is late August before the rainy season starts.

    While you're outside pruning, remember to pick up any rotting fruit on the ground at the same time.

    Pruning Tips:

    Make your cuts with care in order to direct the growth for next year. To have an open tree with good air circulation, make cuts above outward-facing nodes. Choose nodes where you want new growth and make a cut about a quarter inch above, refer to the image below.

    Pruning stages
    Also refer to our page on fruit tree pruning page.

    - January, February, December
  • Dormancy and Chill Hours -

    The positive side of cold weather is that fruit trees native to colder climates, such as cherries and blueberries, may get the chill hours they need to produce good fruit. Going dormant saves energy which can then go into fruit development. No need to protect them on cold nights. Knowing the native habitat of your plants will guide you in caring for them. Mimicking the success of nature leads to greater success in your own garden.

    Learn more about chill hours on the UC Fruit & Nut Information website. UC has historical chill hours available for many locations in California, however, Gilroy is the only location located in Santa Clara County. For county locations closer to the Bay, the Union City station may be more applicable (or view a map of all station locations).

    - January, February, December
  • Controlling Bermudagrass -

    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
  • 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. Fruit trees can have new varieties grafted to them when they are dormant in January and February.

    Scions are available in January 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:

    - Grafting and Budding on the UC Home Orchard website
    - Grafting Dormant Deciduous Fruit Scions at the California Rare Fruit Growers website
    Budding and Grafting Demystified from the UCCE web site

    - 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

2. What to plant

  • 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
  • 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
  • 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 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 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
  • Bare Root Plants -

    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 for 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.

    - January, February, December
  • Poinsettias -

    Poinsettias are a tropical plant 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, UC has Poinsettia Care Tips that describes what to do.

    Poinsettias are beautiful at this time of year due to being forced in commercial greenhouses. If you want to save yours for next year, you will also need to take measures to force bloom in time for the holidays (it's a little tricky, but here's how if you're interested). 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? -

    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.


    Photos: UC Solano Master Gardeners, Growing Amaryllis or is it Hippeastrum?")

    - January, December

3. Pests and Diseases

  • 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 -
    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 Spray -
    Fruit trees and other deciduous woody plants can be treated with a dormant oil spray in the winter. The oil coats insects that “breathe” through their skin and suffocates them. Horticultural oil is generally accepted for use in organic gardening and considered safe for humans and wildlife. It should still be used only if pest problems have been observed. Aphids, mites, and scale can be controlled with this treatment. Spray liberally on branches where problems are evident. Make sure to complete the spraying before the trees start to bud and blossom so as not to damage developing flowers and fruit.
     
     
    Photo: San Jose Scale, by Jack Kelly Clark
    - January, February, March
  • Peach Leaf Curl Preventive Care -

    To prevent peach leaf curl, use resistant peach and nectarine varieties where possible (the Pest Note linked below provides a list.) For non-resistant varieties, treat trees with a fungicide such as a fixed copper spray every year when the trees are dormant (typically December to January). When applying any fungicide, it is essential to cover the trees to the point of runoff or until they are dripping to obtain adequate disease control.

    Generally, a single early treatment when the tree is dormant is effective, although in areas of high rainfall or during a particularly wet winter, it might be advisable to apply a second spray late in the dormant season, preferably as flower buds begin to swell but before green leaf tips are first visible.

    More Information: UC Pest Note on Peach Leaf Curl

    - January, February, December
  • Mosquitoes -
    Make sure you don’t have any water sitting around from our late rains. Mosquitos breed in standing water and can pass along deadly West Nile Virus to people. Check and dump water from any buckets, pots, saucers, dishes, or wheelbarrows. Put containers away or turn them over to avoid collecting additional water. Keep chemicals balanced in swimming pools. Ponds, fountains, and bird baths can also be breeding grounds. Add mosquitofish to these bodies of water to eat mosquito larvae. They are an environmentally friendly means of control and are available free of charge from Santa Clara County Vector Control.
     
    More Information: Mosquito Management
     
    - January, February, March, April, May, October, November, December

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