UC Master Gardeners, Santa Clara County, CA
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UC Master Gardeners, Santa Clara County, CA


Garden Help > Monthly Tips

Good nutrient balance makes healthy garden soils. It is beneficial to get soil tested by a state-certified laboratory. Below is a collection of our monthly tips that relate to garden soils.

Soil Tips

Bone Meal for Bulbs?

Bone meal has traditionally been used as a phosphorus source for flower bulbs, but you may want to reconsider. If your soil is healthy, you may not need it and you may be better off with a balanced fertilizer designed for bulbs or even nothing at all. The nutrient content of commercial bone meal is lower than in the past due to the cleaning process, and the bone smell may attract raccoons or dogs to dig up the bulbs.

Cover Crops

Fava beans growing at our McClellan Ranch project
Fava beans growing at our McClellan Ranch project
You may want to rest in the winter, but the soil life needs to remain active and protected and preferably weed-free. If you’re not planting vegetables or ornamentals in an area for a few months, try plants designed to feed the soil and the organisms that live in it. Cover crops are ideal for putting nutrients back into your soil and keeping weed growth to a minimum. Fava beans are the most popular cover crop in this area and can be seen in abundance in community gardens. Other common crops are clover, vetch, and bell beans. Different cover crops provide a variety of benefits. Beans and other members of the legume family fix nitrogen from the air and make it available in the soil and to plants. The roots also break up heavy clay soil and improve its structure. While fava beans are edible, they provide the most nitrogen to the soil if they are cut up and dug in while they are still in the flowering stage. 

More Information: Choosing and Using Cover Crops

Organic Soil Amendments

After harvesting remaining summer crops, add amendments such as blood meal, alfalfa pellets or fish emulsion to replenish nitrogen in the soil. Add a layer of compost to all existing garden beds to provide needed nutrients for winter crops. Be sure to leave some areas of native soil for ground-nesting bees.

Sheet Mulching - "Lose the Lawn"

An easy and environmentally friendly way to "lose the lawn" is to smother the grass and mulch at the same time. Place cardboard or several layers of newspaper over the area, overlapping by eight inches to keep weeds from finding openings. Wet the cardboard or newspaper, then cover it with 4-6 inches of compost, plant trimmings, or other mulch. Having wood chips on top will give it a neat appearance. The materials will gradually break down and improve the soil over time. New plants can be installed by cutting an X in the cardboard or newspaper and placing the plants right through the mulch. UC Davis Arboretum Horticulturist Stacey Parker's website shows you how it's done.

Soil Management - Compost vs Mulch

Many home gardeners are confused about the terms “compost” and “mulch;” frequently these terms are used interchangeably, but they are not really the same thing. Here is a Comparison of Soil and Mulch from UCCE.

Amend soil with compost to create soil that will retain water but still drain well enough for roots to have the air and water they need.

Benefits of compost
- Forms aggregate particles with clay
- Creates larger pore spaces for water & air
- Helps release nutrients from clay so that plant roots can absorb them
- Supports the soil foodweb by providing nutrients for the organisms
- Lowers pH somewhat.

Benefits of mulch
Mulch does not get worked into the soil. It sits on top of your irrigation system and helps:

- Control weeds
- Prevent erosion
- Preserve soil moisture
- Keep roots cool and moist

Soil Solarization

Soil solarization can be used to control diseases, nematodes and weeds by baking everything under plastic sheeting.The best time for solarization of soil is from June to August. Transparent or clear plastic is the best choice. Leave the soil covered for 4 –6 weeks. Refer to the UC Pest Note on Soil Solarization for Gardens & Landscapes.

Wet Soil

The clay soils which dominate our area are particularly susceptible to compaction, especially when they have received a lot of rain. These soils are characterized by small mineral particles. Hence squeezing out the air spaces makes it more difficult for plant roots and soil organisms to get the oxygen they need to flourish. Try to avoid walking on or using heavy equipment on soil that is wet. Digging in wet soil can also destroy the structure, breaking up useful soil aggregates and earthworm tunnels. Try to wait until the soil is moist, not wet or dry, for easiest tillage. If you must walk or stand on the soil, use a board to distribute your weight over a broader area. Mulch can also create a bit of a cushion and help minimize compaction.

Winter Soil Health

If you are not growing anything special in your vegetable and flower beds, now is a good time to build up the soil health in anticipation of spring planting. Covering it with mulch will hold in moisture, moderate soil temperature, and help prevent germination of weed seeds. Organic mulch (not rocks or plastic), Compost, or manure spread on top will slowly break down over time and feed the soil and beneficial soil organisms. Another way to keep the soil healthy is by planting cover crops.
More Information: Soil Health

Worm Composting

Worm compostingWorm composting also called vermiculture or vermicomposting is a convenient way to decompose kitchen waste and provide nutrient-rich soil amendments for your vegetable garden.

Here is a description for Getting Started.

The Santa Clara County Home Composting Education Program offers Worm Workshop classes.

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