Growing Great Soil

Grow Better Soil with Cover Crops

Improve your soil in one season with very little effort by growing these cool season, easy-to-grow plants.

Does this sound familiar? As winter gets closer and the rains begin, your summer garden beds start fizzling out and are getting muddy and weedy. You’ll wait for spring and longer, warmer days to start growing again. This is a common cycle for gardeners, yet it’s an incomplete cycle, and one that’s unhealthy for your soil and therefore your future crops. There’s an easy cure that requires little effort and makes a big impact on your garden.

Plant cover crop! While typically planted in fall in our climate and left to overwinter, you can also do it in late winter. With the rains and our mild winters, these cool season plants will germinate and grow quickly. They don’t need to grow to maturity, in fact it’s better if they don’t.

What is cover crop?
Typically, it's a mix of legumes, grains/grasses and brassicas grown to improve soil between growing seasons or in between crops to suppress weeds and shade the soil.

How does it benefit soil?
Cover crop is important for perpetuating the soil foodweb lifecycle. The old myth of letting fields go fallow to “rest” them has proven detrimental. Soil is alive, and needs living plants to survive and thrive. Cover crop provides that, and;
• Increases soil nitrogen and prevents the loss of other soil nutrients.
• Suppresses weeds
• Increases soil organic matter, which holds air, nutrients and water, and reduces compaction.
• Improves soil structure
• Increases soil life numbers and diversity.
• Provides habitat for beneficial insects
• Conserves water by slowing evaporation, and by holding moisture near the soil surface.

What should I plant?
• Legumes such as field peas, bell beans or crimson clover that 'fix' nitrogen from the atmosphere and store it in their tissues.
• Grains such as cereal rye or cereal oats for their biomass above and below ground. They add organic matter and aeration to the soil.
• Broccoli and mustard to help suppress soil pathogens, and Daikon to break up compacted soil.

You don't have to plant all of the above, but try to use at least one legume and one grain. If nothing else, plant a legume. If you have too many packets of peas or fava beans around, use them.

How to do it:
1. Buy your seed. I like a mix of field peas, crimson clover, and either rye and oats. If you have disease problems such as verticillium wilt, add broccoli to the mix. If your beds are hard like concrete, add some daikon. I prefer to go heavy on the legumes and light on the rye or oats, say a 70%/30% ratio by coverage. Be sure to buy a packet of inoculant for the legumes if the seed isn't pre-inoculated. It will boost the nitrogen-fixing ability of those plants. Peaceful Valley, Terroir, and Johnny's are a few of the many sources for seed.

Note: I don’t care for vetch as a garden cover crop, because it gets weedy so easily. If you don’t keep it 100% under control it will reseed itself rampantly and for years to come. The cover crop mixes that seed companies offer all contain vetch, so I buy my seed individually.

2. Pull any weeds and clear big debris from the bed. If using inoculant, dampen the legume seed, put it in a bowl or bucket and sprinkle it with inoculant. Roll the seed around to coat it. Broadcast each of your chosen varieties over your bed per the seed packet instructions. Cover with 1/4" of compost.

3. Water. Keep the seed bed moist until you have a good crop of seedlings. Hopefully the rains are doing this for you.

4. Watch it grow!

5. When it's time to plant your summer crops, simply cut the cover crop to the ground and mulch the bed with the chopped up trimmings. No need to till or pull up the roots, just dig your planting holes through the trimmings and roots of the cover crop. You can cover the trimmings with a layer of compost. The cover crop will decompose, returning nutrients and organic matter to the soil.

If you find the cover crop is getting too tall or begins flowering in earnest, cut it back to a manageable height. The legumes are most useful before they put their energy into flowering and setting seed. Chop up the trimmings and leave them in the bed.

Remember, live roots in the soil will keep soil life alive, awake, and thriving. That soil life is helping to fix nitrogen from the atmosphere and feeding other nutrients to your plants.

A few minutes to seed your bed = improved soil health and healthier future crops. It'll take longer to order the seed.

Happy seeding.