Mustards, like many plants, contain compounds that have a variety of effect – on people, other plants, animals, their environment, etc. I would say that every plant does something, though I would say we’ve barely scratched the surface in discovering these effects.
As a cover crop, mustards have several advantages:
- Mustards grow quickly.
- Mustards produce a lot of organic matter, and a decent amount of nitrogen that can be used to improve the soil (whether it’s chopped down and worked straight into the soil and allowed to compost there, or taken elsewhere to compost before being returned to the soil).
- Mustards can act as a fumigant.
It can be useful to clean your soil if you’re having problems with pestilential nematodes or other soil-borne diseases.
Some signs that your plants are suffering from harmful nematodes: Plants may have light-colored leaves, curling leaves, or stunted growth.
These signs would likely indicate nutrient deficiencies, which can be caused by many things, but harmful nematodes may be the culprit, especially if it’s only one plant or one section of your garden.
Pestilential nematodes can suck plants of their resources, causing nutrient deficiencies. Sometimes only sections of the plant will be affected, or it may affect a section of your garden, with all the plants in that section displaying nutrient deficiencies.
You can grow different mustards or other brassicas here and there through your garden, rotating where you place them year after year. The small amounts of fumigants released in the soil will help keep the soil healthy without decimating the beneficial nematodes and other microorganisms in the soil.
Or you can grow a cover crop of mustards (such as the kodiak mustard) in the affected section or across the entire garden, if and where your garden is affected by harmful nematodes.
To effectively fumigate your soil:
- Sow the mustard seed broadly.
- Make sure the soil stays moist until it germinates. Mustards do better when they have enough water throughout their growth cycle.
- Allow them to grow vigorously until you begin to see flower buds – about 5-6 weeks.
- Chop or mow down the whole lot before they set seed (unless you want them to go to seed).
- Immediately work the chopped mustard plant into the soil and allow it to compost in the soil for at least 3-4 weeks. Or you can remove the mustard plants and allow them to compost elsewhere, and then work the compost into the soil, though this will be less effective and fumigate less.
- You should see improvements the next season. If you’re still seeing stunted plant growth and other problems due to harmful nematodes, simply rinse and repeat until you’ve cleansed your soil.
- If it STILL hasn’t cleared out your soil, you can try solarizing your garden soil, or sections of it.
Always remember that plants have effects. Only use mustards to fumigate your soil if you have a problem with pests or diseases in your soil that are affecting your plants’ growth, otherwise you may end up killing beneficial organisms and harming your garden’s living soil system.
Plants don’t have immune systems like humans. But they do have physical and chemical defenses – such as thorns, waxy skin, or chemical compounds that can do many different things.
Nicotine in tabacco plants is a pesticide, which discourages pests from nibbling on tobacco leaves. It is also poisonous enough to humans that 3 pure drops is fatal to an adult.
Many plants in the oregano genus (in the mint family) are effective against diseases caused by bacteria and viruses. Some people feed oregano or marjoram regularly to their pigs to keep them healthy. People used to make tea with herbs (such as lavender, Italian herbs, mints, etc.) for the same effects, and to stay in health.
Some spices are effective against food spoilage, such as garlic, paprika, cinnamon, etc. (It’s no wonder that these are very common in foods made in warm climates, where food spoilage is more likely).
Common sagebrush is offending to many insects, and can be used as a natural mosquito deterrent. Citronella grass is another plant that can do the same thing.
The artemisia family contains many hallucinogens. One of them (A. absinthium) was what affected Van Gogh, who was addicted to it.
Mustards are no different. They can be seriously effective — so use them wisely.