This is an exciting time of year for the medicinal herb farmer! Yes, the ground may be frozen and covered in snow but with that brings so much possibility for the growing season to come. This is the time to plan your gardens while reading through the seed catalogs. When planting medicinal herbs, or weeds, as they are often affectionately called, it is important to remember that these seeds have not been bred as much as vegetable seeds. They still retain much of their wild nature in comparison to vegetable seeds which have been selected, bred and hybridized by humans for hundreds or even thousands of years. Many of the medicinal herb seeds can be treated like vegetable seeds however there are some that need special treatment for successful germination. Medicinal herbs also have very sporadic growing patterns and often do not follow the rules we want them to. There are many obstacles that these seeds have faced so they have formed their own way of protecting themselves and their ‘families’ from huge losses. Growing weeds is not as easy as one would think!
There is a consensus from many herb growers that it is best to start your plants from seeds as this seems to give the strongest plants and preserves the plants genetic identity. Tammi Hartung states that, ‘Plants grown from seed generally have very strong survival instincts that help them adapt to tough climates, critter interaction, insect pests, and disease. However, plants grown from seed occasionally do not develop certain desirable characteristics, such as strong flavor, aroma, and medicinal value, and even cosmetic traits like flower or foliage color.’ There are some plants that cannot be grown successfully from seed, these include comfrey and rosemary. These plants must be grown from cuttings, root division, runner or crown division. This allows for an identical clone of the mother plant.
Before you decide which herbs you will grow I would recommend that you learn as much as you can about where the plant might grow naturally and check wild-plant identification books as they have information about the plants natural habitat. To succeed in growing your favorite plants it is key to know their natural preferences. Researching the treatments needed for the seeds ensures you are prepared for the growing season. Here in New Brunswick the growing season is relatively short so having seeds properly treated allows them to be planted at the correct time for maximum growing. Germination methods include:
Stratification: In this method we are attempting to break the dormancy of the seed by imitating natural forces that stimulate germination in the wild. To do this we fluctuate cold/warm temperatures, light, and moisture. This can be done in a number of ways including planting the seeds in flats, gently watering them and leaving them in an unheated greenhouse for a few weeks before turning the heat on. An easier way to do this would be to mix the seeds with damp sand or peat moss and putting them in the refrigerator for a few weeks. By planting them in the greenhouse and allowing them to feel more natural temperature fluctuations plus the increasing sunlight it seems to help break the dormancy faster and more naturally than the refrigerator method. I have had success with both methods.The seeds will germinate sporadically but eventually they will all wake up. Examples of seeds that need stratification include: anise hyssop, catnip, california poppy, echinacea, hyssop, lemon balm, marshmallow, bee balm (monarda), mugwort, motherwort, mullein, stinging nettle, skullcap, vervain, yarrow and others.
Scarification: In this method we are penetrating the seed coat to expose its endosperm by piercing, nicking, or abrading. This will allow water and air to enter the seed coat and begin to stimulate the process of germination. This can be done by rubbing the seeds over with medium-grit sandpaper until a little of the endosperm can be seen. The seed can then be soaked in water or a seaweed solution overnight until they swell, then planted into flats. In nature, this would occur by a bird or other critter ingesting the seed, their hydrochloric acid would dissolve just enough of the seed coat so when it is excreted the germination process has begun! Plus they have there own personal fertilizer! Examples of seeds that need scarification include: astragalus, licorice and most members of the leguminous family.
Light-Dependent: Some seeds need to be exposed to light to germinate. This is the case with a lot of the tiny seeds. It may be that if they were to germinate too deep into the soil they may not have enough energy to make it to the surface to grow. To plant these seeds , sow them on the surface the soil, cover them very lightly and then water them with the misting nozzle making sure not to wash the seeds away! Examples of light dependent germinators: tobacco, stinging nettle, Saint John’s Wort, wormwood, mullein and others.
Heat Dependent: Some seeds need the soil to be warm before they will germinate. Typically these are seeds that are native to tropical climates. These seeds can be started in flats and put under fluorescent grow lights in a warm room. Once the greenhouse is warm enough they can be placed in there, close to the heater if possible. Examples of heat dependent germinators: ashwagandha, gotu kola, stevia, lemon verbana and tulsi. I also find that ashwagandha is light dependent, I have had the most success by placing it on top of the soil under fluorescent lights while keeping the soil damp.
Direst seeding, much like what is done with veggies, would be a much easier task but the wild plants do not respond well to this method. The exception would be the medicinal cover crops such as oats, red clover, alfalfa and some of the culinary herbs like parsley and cilantro.
Although it may seem intimidating to start plants from seed that does not need to be the case. Do your research, source seeds from a reputable company and then plant them! If you are looking for some beginner herbs to grow from seed I would recommend calendula, chamomile, borage, oats, nasturtium and valerian. None of these require any special treatment before planting.
Below are the seed companies I recommend:
Soule, Deb . 2013. How to Move like A Gardener. Rockport, Maine. Under the Willow Press
Carpenter, Jeff & Melanie. 2015. The Organic Medicinal Herb Farmer. White River Junction, VT. Chelsea Green Publishing. .
Hartung, Tammi. 2011. Homegrown Herbs. North Adams, MA. Storey Publishing.