Medicinal Cover Crop in Orchard
Answered by: Conrad Richter
Question from: Corinna Wood
Posted on: February 26, 2008

I live in the mountains of North Carolina, and I’ve very into the beneficial weeds. We’re creating a small orchard in a clay/some topsoil area which has been recently cleared of trees, and is bare earth. It’s about 4,000 square feet. I would prefer, rather than planting grass, to use seeds like chickweed, yellow dock, plantain, dandelion, yarrow, red clover, etc.

So here are my questions:

1) Do you think its realistic to expect good germination & erosion control from those plants, on this scale? Do you think this is a good idea, in terms of competition, soil stability, etc?

2) What quantities would be enough? I was thinking of 10 grams each of plantain, dandelion, yellow dock, ox-eye daisy, and yarrow; plus 100 grams of chickweed, although I’m concerned the chickweed may not do well if it’s a dry spring.... maybe there’s another you would recommend getting in large quantity. Our soils tend to be a bit acidic for red clover to thrive, but maybe that would work if we lime it well...

What a breath of fresh air it is to get your question! Too often I find myself defending plants like these from those who would prefer to ban them altogether. Invasive plant biologists and government officials are busy putting useful plants like these on prohibited lists, making it harder than ever to grow and appreciate them. The plants on your list include some of our most beneficial healing and nutritious herbs, but their badly outnumbered (and underfunded) advocates don’t stand a chance against the growing invasive plant bureaucracy.

Clearly you are contemplating sowing seeds directly in the area in question instead of sowing in plugs and transplanting to the field. You want to know if these plants will establish themselves successfully from seed, enough to compete against other weeds so (presumably) you can get a marketable crop. Unfortunately, it is impossible to give you an unequivocal answer. If instead you asked is it possible to grow these plants like field crops -- with appropriate crop inputs such as irrigation, weed control, etc. -- then definitely, these herbs will grow successfully and yield a harvest. But your use of the word "competition" suggests to me that you are hoping these plants will thrive enough on their own, with little care, and still give you a harvest. Despite the weedy nature of these plants there is no guarantee that they will flourish enough in your situation to outcompete local weeds. There are reasons why the local weeds are where they are: they are well adapted to the particular ecosystem, including the prevailing pests and diseases in the area, the soil conditions, sun exposure, etc. Almost always imported weeds fail to compete well enough against the local flora to produce new new plants and spread. To understand this it may help to remember that many common flowers and vegetables are weeds somewhere in the world but fail to reproduce themselves in our gardens where the conditions and local flora are very different. The only way to know how things will turn out will be to try. And there is no guarantee that what worked in one year will work the same way the next year, because the push and shove of plant competition can shift directions easily depending on environmental and competitive factors.

Another issue that comes to mind is harvesting. If you hope to produce a marketable crop of dried product from these plants grown as a mix of species, then you will be forced to harvest by hand. Hand labour is expensive compared to mechanized production, especially at the harvesting step. If you are thinking of value-added products you may be able to compensate for the higher costs of production, but like the effect of competition, the outcome may not be clear until you try. There is also the issue of scale. Your plot is small in bulk production terms, and you may have difficulty finding buyers for the relatively small lots you will produce. Dried herb brokers like to see a tonne or more of herbs, whereas you may only get hundreds of pounds. You may have to market to regional wholesalers or to retailers but those markets take effort to break into to.

The seed counts for the proposed herbs are: plantain, 2000 seeds per gram; wild dandelion 1700-1900 seeds/gram; yellow or curled dock, 780 seeds/gram; ox-eye daisy, 1000 seeds/gram; yarrow, 5000-6000 seeds/gram; and chickweed, 600-1400 seeds/gram. At the quantities you propose, and assuming that you are planning to sow all species in a mixture, you will have, per square foot, (all numbers are approximate) 4 seeds of plantain and dandelion, 2-2.5 seeds of dock and ox-eye daisy, 12-15 yarrow seeds, and 15-30 seeds of chickweed. I think the chickweed and yarrow are fine, but the others probably should be a bit more -- at least twice as much. You need to compensate for the normal high loss when sowing small seeds directly in the field. Small seeds germinating at say 85% in the lab will often yield fewer than 10% useful plants in the field. If you don’t sow in a mixture and instead sow patches of each herb then the density of seeds per square foot naturally will be higher. Generally, I would like to see you plant at least 25 seeds per square foot, 50 even if you can afford it.

Because the seeds are small, you should mix the seeds with an inert carrier such as dry, fine sand to ensure a more even distribution of seeds over the area. It is a good idea to split the mixture into two parts and sow one part first and then the second part after, going in perpendicular directions. During the critical germination stage, make sure to allot time to watering and weeding until the seedlings are established and can continue on their own.

Good luck!

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