Starting seeds is a cornerstone of my herbal practice, not to mention my sweet sideline as homestead queen. I highly recommend growing this skill, as it quintuples your access to strange and interesting plants. There is a great, wide, green world of herbs and flowers out there beyond the garden center, and it can be yours for a small investment in supplies, a bunch of practice, and the willingness to try again. Here is an article on starting fussy medicinal plants that I hope you find helpful!
- Soil mix
- Cells or pots
- Quick-read or soil thermometer (optional but good)
- Depth gauge, like a pencil or chopstick with a line drawn on it
- Humidity cover or plastic wrap and duct tape
- Heating pad
- Grow lights or sunny window
- Seedling watering can, or jar with a bendy straw
The basics are easy–it’s all about balancing light, water, and heat. Put the soil mix in a bucket and mix with lukewarm water until it clumps in your hand.
Let the soil warm up until it’s close to the seed’s germination temperature (use the thermometer). Fill the cells or pots and tap to settle the soil. Use the depth gauge to plant seeds to the right depth.
Cover the tray and place on the heating pad. When seeds germinate, remove the cover and heating pad and put the tray in the window or under a grow light.
If you do that, you’ll be able to grow your own starts for most vegetables, flowers, and herbs. With a little more detail, though, you can get your germination rates close to 100% on almost anything you care to grow. Here goes.
Records, Resources, & Timing
Write stuff down—this process takes months and you don’t want to forget stuff or look the same info up repeatedly. Label flats with the name of the plant, date of sowing, and special considerations like “needs light to germinate” or “ideal germination temperature 60 degrees”. You think you’ll remember; you won’t.
Look through your seeds and identify cultural needs like stratifying, soaking, etc., as well as when to start them in your climate. I often use the Fedco catalog, as their cultural information is relevant to us cold climate folks–also, they’re a worker-owned cooperative and deserve your money. I also really like Eliot Coleman’s books. For medicinal herbs, Horizon Herbs & Richo Cech’s book have a lot of great info, but if you live in a cold climate take things like “start in fall” or “overwinter outside” with a big grain of salt because Richo lives in a mild PNW climate and that type of thing doesn’t translate well for those of us with winter. Richter’s is a Canadian herb company that sometimes has helpful info for cold climates. I don’t know anything about warm climate resources, so if that’s you, sorry I can’t be of more help here–feel free to post your favorite resources in the comments, if you feel motivated.
Note when your resources recommend setting out plants: as soon as the ground warms, late spring, after danger of frost, etc. Then count backwards to figure out when to start seeds, adding 1 week for hardening off. For really long season crops that might be hard in your climate—for me it’s habeneros and watermelons—count the “days to maturity” backward from your fall frost date, to make sure you get them going early enough.
You can make or buy a seed starting mix. There are a lot of ethical issues surrounding growing media like sphagnum, peat, and perlite, so chew that over before you buy the detritus of what was once mountains and wetlands. I’m not going to reprint recipes here but they’re easy to find. I use a DIY version of Eliot Coleman’s soil block recipe from New Organic Grower.
Humidity is the combination of water and heat, and is essential to good germination rates.
Cover your seed trays with either a commercial cover or plastic wrap and a seal of duct tape. The warmth from the heating pad evaporates water in the soil, which then condenses on the cover and rains back on the soil. This gives even moisture and nutrient dispersal across the seedbed and simulates the spring rain and dew cycles. You lose moisture and warmth when you remove the covers, so no peeking until you see green.
Seeds: Seeds need warmth to germinate; look up the ideal germination temperature for your seeds. Heating pads really increase germination rates, and they sell ones specifically for seeds that are waterproof and don’t get too hot. That said, you can use a regular one, just be careful with water around it and know that it may get too hot. Test it first by putting it under an empty seedbed for 24 hours and then temping the soil.
Plants: In the beginning keeping trays warm can be a challenge, but as the plants grow they put off their own heat so make sure you have a way to cool down the room if necessary. A fan can prevent fainting on warm spring days. If you’re growing plants with different temperature needs, do it in stages: brassicas first, then move them to a cold frame as the nightshades start setting true leaves, etc.
Seeds: Watering is risky: seeds can rot or get dislodged, or soil gets muddy and cracks when it dries so seedlings can’t push through. If the soil dries out under the humidity cover, use a spray bottle, or fill 1 cell with water to increase the humidity.
Plants: Once your seedlings have unfolded, remove the cover and give them a drink without knocking them over. Soil should be dry but not baked. Under-watering twice a day is better than overwatering once a day, to avoid damping off. More water is usually not the solution to any problem, unless the plants have bent over away from the light in a deep bow, in which case a little sip will perk them right up. Less is more with water!
Seeds: Window light is enough for light-dependent germinators. If grow lights are turned on before germination, the soil can get way too hot.
Plants: When plants are up, remove covers and position lights several inches above seedlings so they don’t get leggy. If you’re using a window, back it with a mirror so the plants get light from both directions. There’s a lot of discussion about how many hours a day seedlings need to flourish, and the answer is it depends on the plant and the kind of light. I give them my day, because they’re going to have to make it in my climate anyway.
Simulating Natural Conditions
This is where it gets complicated. A lot of herbs, especially the at-risk ones, are fussy germinators—they just won’t grow under normal conditions, or you get a terrible germination rate. The key is to ask yourself what natural conditions the seed would be exposed to in its natural environment. Many resources have this information, but I’ve found that many seeds benefit from these treatments even if the books don’t mention it. Again, those of us in harsh climates do things a little differently than our more temperate counterparts.
Allow space for intuition: watch how and when wild plants grow, and build an understanding of their needs. The following techniques cover most natural conditions that can be a limiting factor in germination.
Stratification mimics the freeze-thaw cycle of winter and spring. For wet stratification, wrap seeds in a moist paper towel or rag, then put it inside a plastic bag in the fridge, away from high-moisture foods like tomatoes and apples (and then take your tomatoes and apples out of the fridge before you destroy the nutrients, goofball). For dry stratification—this is less common—put the seeds in a pot with a little soil, again in the fridge.
Stratify fussy germinators that are native to places with winter. Some seeds need a long time, like 3 months of wintery conditions. Others need multiple stratification: cold for a month, then room temperature, then cold again for a few weeks, room temperature, cold for 1 week, etc. to really simulate spring; I do this routine for our fussy woodland natives, as well as difficult-to-germinate cold climate natives from elsewhere. It’s generally the first thing I try if I don’t know what to do.
Scarification mimics the physical breakdown of the seed coating in an animal’s digestive tract. Just sand the seeds a little, or if they’re big enough, nick them with a knife. Think about which plants rely on animals to spread their seeds, as well as seeds that have really thick, impervious coatings, so they can last a long time in the soil before germinating. Usually scarification is combined with a second treatment, like compost or soaking.
Fire is pretty specific to prairie natives, although I bet there’s a bunch of plants that would like this treatment out on the West Coast where they have all those forest fires–I don’t know because I don’t grow any, but if you do, let me know if fire improves your germination! Anyway, spread the seeds on a baking tray or something else that won’t catch fire and use a grill lighter to burn them (gently! gently!). Some people plant the seeds first and then burn the soil, or even build an actual fire on top. This is often followed by soaking—if you’re Echinacea pallida, your spring routine is ruled by flood and fire.
Soaking is probably the most common and combines well with most other treatments. It mimics rain and spring flooding, a biological alarm clock, and softens hard seed coatings, making it easier for the seedlings to poke through. Use non-chlorinated water and soak the seeds for a day or so. If you really have to use chlorinated water, let it sit on the counter for 24 hours before you put the seeds in.
Compost gives a nutrient boost to seeds that have to pass through an animal’s digestive tract before germinating. It’s almost always combined with scarification. Put a little compost in the bottom of the seed tray with your regular soil mix on top. The water cycle within the seed tray will disperse the nutrients slowly and make them accessible to the seedlings. Most seeds do not need this, and in fact can be burned by compost, so only do it if it’s actually necessary.
Overwintering is appropriate for cold climate natives, if you get to it in the fall. It provides the benefits of stratification and soaking that so many plants need. Prep fertile garden beds in the fall, direct seed, and mulch well—think dead prairie grass or goldenrod, really protective. In mild climates, people overwinter seeds outside in pots, but in cold climates that’s unreliable because there’s no natural insulation that the ground would normally provide. I’ve had this work occasionally, but really only with plants that are actually native to a place that routinely has 4+ feet of snow. A shed can work, but then you have to remember to water it in the spring.
Good luck, hooray for spring, and send me your success and failures!
This article was first published in the spring issue of The Country Grind Quarterly, where I write a column about making and using herbal medicine. Even though starting seeds is technically maybe a little off topic in that setting, I sent it in because it felt relevant for the spring issue. It’s certainly involved in “making herbal medicine,” if higher on the food chain. Also, it’s what I was thinking about at the end of February, and I was having trouble redirecting. And now I will share it with all of you.