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Cover Crops: the Organic Gardener’s Green Manure

Cover Crops: the Organic Gardener’s Green Manure

Cannabis growers more often than not grow in highly amended soils that are light and airy. I have seen many using straw to keep in moisture, and a few that are adding cover crops to their pots. Cover crops offer a multitude of benefits. If you haven’t used them in the past, you might consider them in the next cycle.

Some of the toughest work in your garden can be accomplished by enlisting the help of other plants. You may already be familiar with the concept of cover plants as green manure – plants are grown and returned to the soil as fertilizer before they reach adulthood – but cover plants serve other vital functions in your organic garden as well.

Pest control – Flowering crops can attract predatory insects, such as solitary wasps and lacewings, and protect your organic gardening efforts from aphids and other pests.

Weed control – The shade provided by leafy cover plants can prevent the growth of nuisance plants so that they are not able to take root before you begin growing your next primary crop.

Water control – Cover crops slow down soil erosion by creating a breaker between rainfall and the surface of the soil. They also slow the rate at which water travels below the surface and can significantly increase soil moisture once they are tilled into the soil.

Fixing Nitrogen— Legumes are plants that produce nodules in the soil that fix nitrogen, leaving it available for the next round of plants. Residual N in your soil can reduce the amount of fertilizer you need to purchase and apply.

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The most well-known purpose of cover crops, however, is their use as a fertilizer. To profit from their use as a green manure and from the benefits listed above, simply sow the seeds from your cover plants and allow them to grow until they begin to flower (or produce seed heads, in the case of grains). It is important to kill your cover plants before they mature too much; they are meant to aid your primary crops, not to be crops in their own right. Simply mow over the crops or cut them down with a trimmer, allow the clippings to dry for a couple of days, and then dig or till the clippings into the soil.

Common cover crops include:
Legumes and grasses (including cereals)
Brassicas (such as rape, mustard, and forage radish)
Hairy Vetch

If you are new to the idea of cover crops, give it a try. Look for a mixture of 8 or more types of seeds to get a wide array of benefits. You’ll be happy you did!