Garden
Cover Crops & Mulching
Investing in Next Year’s Garden
As you finish harvesting your summer crop of crispy beans, fragrant herbs and sweet tomatoes, you can turn your energies toward tending the fall garden. A sustainable organic garden is dependent on the health and nutrients in your soil. Our rainy PNW winters tend to leach nutrients out and wash them away. Replenishing your garden soil over the winter months while you are warm and cozy inside is as easy as adding a layer of mulch and/or planting cover crop seeds.
In the Vegetable Garden
After a harvest, many gardeners plant a cover crop or “green manure” crop such as legumes, clover, or a combination of rye, vetch and clover. Cover crops fix nitrogen in the soil while building texture, improving aeration and drainage, as well as adding organic matter.
Bonus: Planting a cover crop also keeps out the weeds over the winter. Cover crops are tilled in before they go to seed (or simply turned with a shovel), and break down quickly so a new harvestable crop can be planted right away.
Choosing a Cover Crop
Start by understanding your soil type: sandy, clay, or loamy. No matter your soil type, cover crops will help by feeding the microorganisms in your soil and protect the nutrients from being washed away by winter rains. You can find a variety of cover crop seed at Molbak’s. Keep reading, we have some suggestions based on soil types below.
Sandy
In sandy gardens, plant a winter wheat or rye. The fine roots help hold nutrients in the soil. In the spring till or turn the garden over with a shovel to build the soil.
Clay
Those with clay soil can use a clover to break up the soil or legumes, which tap roots loosen compacted soil and bring valuable nutrients up from the sub-soil.
Any Type
When in doubt, use Crimson Clover or choose a 3-way blend, which includes a mix of seeds good for all soil types.
Mulching
Spreading mulch is another way to feed and protect soil over the winter. Mulch, a layer of material spread on top of the soil, can be anything from compost to straw. Mulching can keep weeds down, protect beneficial soil organisms, and add valuable organic matter.
In Garden Beds
Over-wintering vegetable, perennials, shrubs and garden beds slated for early spring planting are all good candidates for mulching. Mulching around trees and shrubs protects roots from severe cold.
Trees & Shrubs
Layer mulch 3-4″ deep around shrub where you estimate the roots to be. For the health of your shrubs, keep a 3-4″ ring around the base of any woody trunk free of mulch.
Garden Beds
Add 6-12″ of mulch over any empty garden beds. When you are ready to plant in the spring, turn the mulch and soil together and plant!
Soil Types
Sandy Soil:
Sandy soil feels gritty and has large particles. It drains easily allowing water to move through it quickly, which in turn washes nutrients away during winter rains. Sandy soil requires organic amendments such as such as an organic fertilizer blend. It also benefits from mulching to help retain moisture.
Clay Soil:
Heavy clay soil feels lumpy and is sticky when wet and rock hard when dry. The clay holds water and drains very slowly. Waterlogged soil can rot roots of over-wintering plants and drive away beneficial soil organisms. Clay soil is poor at draining and has few air spaces. If the drainage for the soil is enhanced, then plants will develop and grow well as clay soil can be rich in nutrients.
Loamy Soil:
Loamy soil is an even mix of sand, silt and clay. A handful feels fine-textured and slightly damp. This soil has ideal characteristics for gardening and is easily cultivated. It warms up quickly in spring, but doesn’t dry out quickly in summer. Loamy soils require replenishing with organic matter regularly, and tend to be acidic.
Our 3-way cover crop blend works for any type of soil and is cold hardy; designed for our Northwest winters.
Additional Resources
Soil Testing:
If you live locally in King County, Washington state, you can get a free soil test from the King Conservation District. They test for Nitrogen, Phosphate, Potassium, Magnesium, Calcium, Sodium, Sulfur, Organic Matter, pH, and Cation Exchange Capacity. The laboratory will analyze your soils and provide recommendations specific to your plant needs.
Soil Questions & Info:
The Tilth Alliance has soil and gardening information. You can email them or reach them on their hotline.
No matter which method you choose, a little work now can make a big difference in the health and productivity of your garden next year. So take advantage of the cooler autumn afternoons and do a little mulching and cover cropping!
Garden Solutions for Every Season
