Guidelines to Growing Medicinal Herbs from Seed
Written and Photographed by Juliet Blankespoor
No matter how many years I plant seeds and watch them grow into mature plants, I am still awed. I feel an utter child-like excitement when I see the first sign of a sprouting seed poking out of the soil. Germinating seeds are a universal symbol of hope and renewal, ushering in the joy and promise of spring. In a world growing more complicated and technological by the day, it is a comforting pleasure to witness the simple, yet miraculous, processes of plant life. As an herbalist, I strive to cultivate direct relationships with the living medicinal plants I use in my practice, either through growing or wildcrafting. I came into this craft through my fascination with plants, along with their myriad offerings; growing medicinal herbs is one of the greatest joys in my life.
I have been growing plants for the last two decades and, like every gardener, I have learned as much from my mistakes as my successes. Growing up in the suburbs, I spent little time gardening; I didn’t catch the plant bug until I left home. My first vegetable garden was pretty much a flop, as I really had no clue what I was doing. But in my mind, I was now a gardener, and ready to try again the next spring. And luckily, many of my friends had green thumbs, or grew up on farms; they took me under their wings and taught me skills that are now instinctive.
When I started growing herbs, I soon realized that I had to pay attention to details and learn a whole new set of germination skills. Most of the annual vegetables we grow have evolved with the agricultural practices of humans, and thus have been selected over the millennia to have uniform, quick, and relatively easy germination. Not so with most of our medicinal herbs, especially considering that many of them are perennials, which typically have a more selective strategy for germination (with less of the live-fast, die-young lifestyle of annual plants). For the last five years I have nurtured an herbal nursery, and have learned even more tricks from other growers, as well as from watching and listening to the plants themselves.
Following is a special note on intention. Some years back we experienced an almost total failure in germination for most of the seventy species we planted. We re-examined all the variables: same soil mix we’ve been using for a decade, same fertilizer, greenhouse, etc. Now there’s always a chance that we missed an important ingredient, such as lime, which would adversely affect the pH, or our composted manure was too hot, or something to that effect. But, in reviewing our seeding scenario, I came to the conclusion that we sorely needed some ritual and prayer during planting time. By the time we are seeding, we have spent many moons in anticipation of this special moment, from the gathering of seeds to their stratification, the careful planning of the seeding schedule, and the formulating of soil. In addition to all of the material preparation, we are awaiting and co-creating the rebirth of the green world. Conjuring up a miracle in spite of frigid temperatures and gray skies. On a personal note, our first planting is also the beginning of my apprentices’ time working with my family and me, and I always want to honor the sanctity of those unfurling relationships. Now we mark our initial seeding with prayers, spoken intention, songs, and smudging. Since the inception of this little ritual, we have had very successful germination but, more importantly, our sense of place, community, and season has deepened.
My goal here is to lay out the most common systems for seed starting and the basics of caring for seedlings, including typically encountered problems, in the hopes that you are able to grow more plants to love, eat, and make medicine from. In addition, I will outline the special germination techniques necessary for many medicinal plants.
Direct seeding versus tray culture
Planting seeds directly in the garden has some obvious advantages, notably the absence of resources and energy necessary in seed tray culture. It is the easiest choice, and for those plants who do not tolerate transplanting, it is the only choice. The downside to direct seeding is the higher attrition rates with tender seedlings left to fend for themselves in the face of frost, competition, herbivory, drought, and disease. For plants with longer germination periods, the weed competition can be a major factor, especially if you aren’t familiar with identifying the seedlings of the planted herb. However, the plants who do survive and reproduce will have offspring selected for their parents’ tenacity and vitality. Some plants that generally have good survival rates with direct seeding are: calendula, basil, holy basil, feverfew, German chamomile, borage, garden sage, skullcap, Echinacea, boneset, and anise hyssop. Many herbs need a period of moist cold before they germinate; these herbs may need to be planted in very early spring or in the fall. Check the resources below for each herb’s specific needs. For woodland perennial herbs with a two- to-three year germination period, planting directly in a prepared forest seedbed may be easier than keeping track of a seed tray for such a prolonged period.
In addition, the following plants are typically seeded directly because of their dislike of transplanting, or because of the larger plantings inherent in cover crops: oats, California poppy, opium poppy, cilantro, parsley, khella, red clover, alfalfa, and fenugreek. I am somewhat of a control freak, so I rarely seed directly (except for the aforementioned herbs) and prefer to watch over my babes more closely in a greenhouse.
Plastic seed trays are easy to acquire, come in a variety of sizes, and are often cheap or free. My nursery got its start with discarded mismatched seed trays, which I reused for years. An advantage to the seed trays with especially small cells is the ability to seed more plants in a relatively small area, which is especially helpful if you are planting in front of a small window, in a small grow light area, or you just want to heat a smaller greenhouse in the early Spring when it is still very cold. Obviously, with smaller cells you have to step up (transplant to a larger pot, or cell) your plants earlier (often when their first true leaves appear). Many medicinal herbs have longer periods of germination, so less precious space is wasted while we wait for their emergence.
Note about sterilizing seed trays: I do not sterilize my seed trays for a number of reasons. One, it is a pain in the derriere, and two, my soil is alive with mycorrhizal fungal spores and beneficial soil bacteria from compost and worm castings. Plants with a healthy diet and environment, including beneficial flora, have more vitality to fend off potential pathogens. I focus more on helping to create a healthy terrain than combating disease. Preventative medicine is for plants too! If you do wish to sterilize, try using a hydrogen peroxide solution instead of bleach. Brewing supply centers sell many affordable eco-friendly sterilizing products.
I do have concerns about the environmental impact of chemicals used in manufacturing plastic, and the potential for endocrine-disrupting substances to leach from plastic containers and enter the soil and the plants contained within. Recently, biodegradable pots made from peat and/or manure have entered the market, and while more expensive, they may be better choices environmentally. Unfortunately, many are not manufactured domestically, so check their origin. Which brings us to another choice in containers-- no container at all, the soil block.
These are blocks of soil, prepared from soil block makers, which are specialized metal forms with handles used to gather up moistened soil. The forms are used to create a row of soil cells, which are deposited on a wooden or plastic tray. Soil blocks were popularized by garden writer Eliot Coleman and are preferred by many organic farmers. The individual blocks are open to the air, so the plants roots growing in them are air pruned and cannot become root-bound, and consequently take off quicker after being transplanted. The forms come in a variety of sizes and can be stepped-up with the growing seedling. Once you get the hang of preparing the soil, reaching the proper moisture balance, and using the soil makers, the block making process can go quite quickly and efficiently. Soil block makers require a larger initial investment, but can last for many years if cared for properly. Another distinct advantage is the absence of plastic when using wooden trays and soil blocks. watch this video on making soil blocks
Heating the soil, through applying heat under seed trays, greatly improves the speed of germination, an important factor for medicinal herb seeds, which often have lengthy germination periods. There are a number of methods people use to achieve bottom heat. The most popular and easy is the electrical mat, which goes under a seed tray and comes in varying sizes, fitting underneath one to four seed trays. Some growers use special electrical lines that are run through a bed of sand, with the trays nestled in the warm sand. Another option is running hot water in pipes just under the surface of the soil in a greenhouse, with the heat provided by solar hot water heaters, with an on-demand propane heater as a back- up heat source. Yet another intriguing system is to build a hot compost pile in a greenhouse and place the trays upon the exothermic bacterial party.
It is helpful to have a soil thermometer, an inexpensive tool available from nursery and garden supply companies, to closely monitor the soil temperature. An ideal soil temperature for most seeds is 60 to 80 degrees F; I typically try to keep the soil between 65 and 75 degrees. It is important to not let the nighttime soil temperature dip too low as most seeds will bide their time until the soil warms more evenly. In addition, take care to not overheat the soil, as tender seedlings can easily desiccate or be damaged by excessive heat.
How I love the quiet timeless magical hot greenhouse on a cold early spring day. Greenhouses can be built from glass, or thick UV resistant plastic (our 10 mil greenhouse plastic has lasted seven years). Old PVC pipes are often available for free or cheap from well drillers who cannot reuse them; they can be used to build hoop houses supported on posts made from rebar pounded into the soil. Alternately you can dig a hole with a steel bar and place the pipe directly in the soil. One-inch, schedule forty pipe, in twenty-foot lengths, will give you a nine-to-ten foot wide greenhouse with a six-foot height. If you live in an area with snowfall, remember to create ample slope in your hoop houses so the heavy snow doesn’t pile too thickly and break the greenhouse. In our area, one intense winter storm brought down dozens of greenhouses. I have spent a good bit of time brushing heavy snow off our plastic greenhouses-- snow can pile up, even with their generous slope.
Consider building a small greenhouse off the south side of your home if it receives ample sunlight. The thermal mass of the house will store heat from the sun during the day and radiate it off at night when it is needed.
Airflow is a greenhouse is paramount, both for lowering temperatures on sunny days, and minimizing fungal diseases. Design a greenhouse that allows for both ends of the greenhouse to open. Alternately, the bottom portion of the sides can be rolled up or raised. Fans are useful, and can be aimed to move air directly over seedlings to help prevent damping-off, a common fungal disease of seedlings (see below).
Start your trays on a table or shelf in front of a south-facing window. Little to no investment is needed and typically no auxiliary heat is necessary. You may need to put your seedlings outside in direct sunlight on warm days. If your seedlings grow spindly or fall over, they needs more direct sunshine.
This germination set-up requires a start-up investment and obviously uses more energy than other methods. Full-spectrum fluorescent bulbs more closely replicate the spectrum of light found in sunlight.
I recommend finding a very fine soil mix, which has been screened to a smaller particle size. It is easy for some of the tiny herb seeds to fall into larger cracks in coarse soil and never make it up to the surface. We add a moderate amount of an organic fertilizer bend to our soil recipe: a combination of blood meal, bone meal, and greensand. In addition, we add a mycorrhizal inoculant and small amounts of worm castings. We also add sand and actinovate (a bacterial inoculant), both of which help prevent damping-off.
Following is my soil mix recipe for germinating herbs. It can be used for vegetable germination as well, but I formulated it specifically for smaller herb seeds. The fertilizer is enough to get the plants started but additional fertilizer, in the form of foliar feeding, will be needed when the seedlings grow their first true leaves. Sifting the peat and using smaller perlite are important steps in keeping the texture of the mixture fine enough for tiny seeds.
Fine Germination Soil Mix for Herbs
*5 gallon bucket = 1 part
- 2 parts sifted peat
- 1 cup lime
- ¼ cup bloodmeal
- ½ cup greensand
- ½ cup bonemeal
- 1 ¾ part fine perlite
- ¼ part fine vermiculite
- 1 part sifted bagged compost (to avoid weed seeds)
- 2 cups worm castings
- ¼ cup mycorrhizae (modify proportions according to the directions on the specific brand of mycorrhizae you are using)
- 3 quarts fine sand
- Actinovate (follow the directions on the label)
I recommend wearing safety goggles and a mask to protect the eyes and respiratory passages from the dust and potentially harmful perlite. Sift the peat through a screen to remove large pieces and break up clumps. Place a screen with ½ inch holes over a wheelbarrow and mix the peat through. Add the lime, bloodmeal, greensand, and bonemeal and mix thoroughly. Add the other ingredients and mix with zeal and zest. Wet the soil thoroughly and add the actinovate (employ proportions as described on the label).
Watering medicinal herb seeds requires more attention than watering vegetable seeds as many seeds are tiny, or planted on top of the soil, and can easily be dislodged by regular watering. We water emerging seedlings with a metal mister, designed for a propagation greenhouse misting system, which we attach to the end of a hose (after first adding a filter so the fine orifices of the mister don’t clog with particulate matter). Alternately, you can use a watering wand nozzle attachment turned to the mist or fine spray setting. Just make sure it is a gentle enough spray for wee seedlings. Be prepared to spend a good bit of time watering, as thoroughly wetting the soil with fine misting is a slow going process. Another possibility is placing a non-draining tray under the seedlings and letting the water be sucked up into the soil through capillary action. Once the seedlings develop true leaves they are probably ready for the hard knock school of regular watering, which provides the tough love needed to prepare precious innocent sprouts for the real world of wind and rain. Make sure you are letting the soil dry out in between watering, not enough to cause wilting, but enough to let the soil get almost dry. Watering is a fine dance; it requires responsiveness to your dance partners, the plants, along with the musicians: light, airflow, and temperature. Flow with the changing ambient conditions, your intuition, and a close observation of the plants themselves.
I recommend using a small amount of organic fertilizer in your germination mix and periodic foliar feeding as the seedlings emerge. Foliar feeding applies nutrients onto leaves where they are absorbed directly. In my experience, foliar feeding greens-up plants quickly and is well worth the time and energy. We use a diluted mix of fish emulsion and seaweed run through a sprayer, applied after regular watering on the morning of a cloudy day. Too strong a preparation can easily burn plants on a sunny day and some plants are more sensitive to the nitrogen than others. Start with a very dilute mixture and slowly increase the concentration over time as you observe the plant’s response.
Special seed treatments:
Following is an abbreviated version of special seed treatments, for a full discussion on this subject please visit my article on Cultivating Medicinal Herbs.
Stratification or Cold Conditioning– Many seeds have a built-in alarm clock that lets them know winter has passed and it is now spring, and safe to begin life. Stratification tricks seeds into thinking winter has passed by exposing them to an extended period of cold and moist conditions. Stratify seeds by planting them in the garden a couple of months early or by placing the seeds in moist sand for one to two months in the refrigerator. Boneset, ginseng, blue vervain, butterfly weed, blue cohosh, black cohosh, bloodroot, goldenseal, trillium, wild yam, wild ginger, false unicorn root, culver’s root, mullein, skullcap, wormwood and Echinacea spp. are just a few of the herbs that need stratification to germinate well.
Light-dependant Germination –Sow these seeds directly onto the surface of the soil and very gently press them so they make contact with the soil. They then should be watered very gently by misting or bottom watering so they will not be washed off the surface of the soil. Many very small seeds are treated in the same manner, as they do not have the reserves to grow above a thick layer of soil. Angelica, bee balm, catnip, lobelia, lovage, mullein, Saint John’s wort, and violet are just a few of the herbs that need sunlight to germinate.
Scarification –Rub the seeds between two pieces of sand paper until you see a little bit of the endosperm (embryo nutrient reserves, usually a lighter color and different texture than the seed coat). Sometimes this is done before stratifying seeds and sometimes at the time of sowing. Astragalus, wild indigo, hollyhock, licorice, marshmallow, passionflower, red root, and rue are some of the herbs that will germinate better with scarification.
If your greenhouse has little airflow, consider hardening off your seedlings by gradually exposing them to increasing amounts of sunlight and wind before you plant them directly in the garden. Plant your seedlings in the garden on a cloudy day, or in the afternoon, and water well. You can use a diluted seaweed tea or willow twig tea to encourage root growth. If your plant is root bound (roots coiled around the edge of the soil), try and break them free and loosen the roots before planting.
Troubleshooting Common Problems with Seedlings
My seedlings are spindly, yellowish, and stretching toward the light.
Get these babes to more light. Put them outside on sunny warm days in full sunlight (just a little on the first day, building up more time with each mild sunny day).
My seedlings are keeling over, pinched at the level of the soil, and now it’s spreading like wildfire; the neighboring seedlings are also biting the dust.
You got yourself a case of damping-off, a commonly encountered disease affecting seedlings, which is caused by a number of fungi. Try increasing ventilation with fans, open windows, etc. and increasing sunlight (if possible). Take care to not overwater (see previous notes on watering). We add sand to our soil mix, and many growers add a fine layer of coarse sand on top of the soil, both of which discourage fungal activity. In addition, we use an organic biological fungicide from a product called Actinovate. We add this bacterial inoculant to our germinating soil mix and periodically water our seedlings with the diluted spray.
My seedlings are slightly yellow and just don’t seem to be growing very fast.
Your seedlings probably need more nitrogen. Water them in with diluted compost tea or fish fertilizer. See the previous notes on fertilization.
May your gardens be bountiful, and provide nourishment, beauty and healing.
To be of the Earth is to know
the restlessness of being a seed
the darkness of being planted
the struggle toward the light
the pain and growth into the light
the joy of bursting and bearing fruit
the love of being food for someone
the scattering of your seeds
the decay of the seasons
the mystery of death
and the miracle of birth
Seeds, Plants and Gardening Supplies
Horizon Herbs – Largest collection of organically grown medicinal herb seeds and plants. Catalog is also a growers manual and contains many of the germination specifics listed below.
Richters – Huge selection of herb seeds and plants. Rare or hard-to-find herbs.
Prairie Moon Nursery – Seeds and plants of natives to the prairie and eastern states. Loads of germination information in their seed section.
United Plant Savers – Nursery and Bulk Herb Directory (available free to members)
Fedco seeds and Organic Garden Supply – cooperative seeds, trees, and gardens supply, located in Maine
Johnny’s Selected Seeds – Large selection of garden/farm supply
Medicinal Herbs and Non-timber Forest Products – Useful links to many websites devoted to the topic of cultivating medicinal herbs. Dr. Jeanine Davis of NC
Production Guides, written by Dr. Jeanine Davis and Jackie Greenfield. Covers the specifics of cultivating the following medicinal herbs: American ginseng, black cohosh, bloodroot, Echinacea angustifolia, E. pallida, E. purpurea, false unicorn, ginkgo, goldenseal, skullcap, wild indigo, and wild yam.
Fedco Seeds Planting Chart – Cultural information and planting chart for herbs
Medicinal Herb Gardening Books: Please visit the resource section at the end of Cultivating Medicinal Herbs.
This article was previously published in Plant Healer Magazine, the paperless quarterly journal of the new folk herbalism resurgence – a downloadable, beautifully illustrated, full color PDF magazine.
Meet The Green Mastermind Behind Blog Castanea
JULIET BLANKESPOOR founded the Chestnut School of Herbal Medicine in 2007 and serves as the school’s primary instructor and Creative Director. She's been a professional plant-human matchmaker for close to three decades. Juliet caught the plant bug when she was nineteen and went on to earn a degree in Botany. She's owned just about every type of herbal business you can imagine: an herbal nursery, a medicinal products business, a clinical practice, and now, an herbal school.
These days, she channels her botanical obsession with her writing and photography in her online programs and here on her personal blog, Castanea. She's writing her first book: Cultivating Medicinal Herbs: Grow, Harvest, and Prepare Handcrafted Remedies from Your Home Garden. Juliet and her houseplants share a home with her family and herb books in Asheville, North Carolina.
Looking for more blog articles about medicinal herb cultivation?
Remember, we’ve got a wheelbarrow-full of herb gardening and seed starting resources on the blog. Come on over to browse, pick up our personal gardening tips, and learn about our can’t-live-without garden medicinals.