Here’s the good news – you don’t need anything super fancy! And depending on the scale to which you are wanting to propagate, you might not need some of these items. For example the growing trays and humidity domes can be replaced by reusing clear plastic clam trays with slits cut in the bottom; these work well if you are only wanting to grow a couple of species at a time. I tend to grow 25-40 species each year and need the dimensional organization that the growing trays provide.
- Growing trays without holes
- Growing trays with drainage holes
- Vented Humidity Domes. These domes need to fit the growing trays.
- Deepots (D40H) and stand. These are purchased from Steuwe & Sons
- 2.5” pots
- 5-6” pots
- Pocket trays for the 2.5” and 5-6” pots. (optional) These are not necessary as the growing trays without holes will work fine. The advantage these have is the pots don’t top over easily.
- Shelving unit and/or table
- Grow lights. These can be created from work light fixtures and Grow lights from a discount home supply store. I found the super high powered from the greenhouse supply houses are unnecessary.
- Cold frame (optional), This isn’t absolutely necessary but makes life easier. Without one plan to spend time moving trays in and out of your garage.
- Potting mix
- Peat moss
- Labels with black marker
I have found that with the Grow lights, there is no need for the heating mats underneath. The mats are great for using in the cold frame when all my growing space in the house is filled and it is below 50° outside.
My Set up
My propagation set up is in the mechanical room. I use a 6’ table with Grow lights on chains hanging from the ceiling and a 3-shelf unit with Grow lights hanging underneath each shelf. This is where the plants are moved to once they have been stratified and are ready to germinate. They stay here until they are large enough to successfully go through the hardening off phase. Depending on my level of success in germinating the plants, I harden off in the cold frame or in the garage. See Hardening Off for more info on this process.
Germinating the Seeds
Certainly, this is the tricky part!! Norman Deno conducted a number of tests on seeds in order to document their exact needs for germination. This is my “go to” resource. Native seeds have different requirements that stimulate germination; these requirements are designed to enhance their ability to successfully disperse their seed before they germinate and multiply. Basically, you need to think like a seed. If you buy seeds from Prairie Moon, they provide you with a recommended germination guide for each type of seed. I have used their guides successfully as well.
Many native forbs require a period of cold, moist stratification; in general, this is about 2 months of 40° followed by a period of 70°. But there is a variety of needs that seeds have. Some need light to germinate; others need an alternating cold, warm, cold; some need to be inoculated; some need a special plant hormone called Gibberellic Acid-3 (GA-3); some need warm temperature only; and others need cold temperatures only. To be successful, it’s necessary to understand which seeds require which treatment. Grasses will germinate at 70° without any prior treatment.
I have tried various scarification methods such as sandpapering and nicking. Scarification is usually suggested with legumes because their seed coats are very hard. I have found that using the proper inoculant and cold moist stratification is all that is necessary. Each legume has a specific Rhizobacteria species that forms a mutually beneficial relationship. Inoculating seeds is very easy. Most reputable companies who sell seeds commercially will provide the inoculant. If you have collected your own seed, Prairie Moon will sell the inoculant for the plant. Fortunately, they list the inoculant by the plant that it helps rather than by the Rhizobacteria name!
2 Stratification Methods:
There are 2 ways I’ve stratified my seeds. One way is by placing the seeds on one half of a paper towel, then folding the towel over and spraying it until it is moist. Once moist, place it in an unsealed baggie then place the baggies in a container with the open end up. The advantage to this system is the amount of room necessary for stratifying. The biggest disadvantage I’ve found with this system is with damp paper towels, it’s sometimes difficult to get the seeds off of them and into the substrate for the 70° period.
The second method is placing the seeds in the substrate from the beginning and placing them in a protected area outside. I use our screened in porch. Occasionally, when it snows, I throw snow on top of them. We have cats, so I have to place screens over the trays so the kitties don’t dig in them!
The method that you chose depends on your space. Whichever one you use, it’s imperative that you don’t let them dry out; this stratification period requires moisture and cold. It is generally this moisture that destroys the germination inhibitors. Think of it the way the seed would; it would not want to germinate during a drought.
How to apply inoculant:
This method will work great even if you are planting a number of acres! If you have some non diet soda around, use this, otherwise, mix up some sugar water – a quart cup of sugar to 1 cup of water is a sufficient ratio. Place the seeds in a plastic container and put the sugar water in a spray bottle; spritz the seeds until they are completely covered, then sprinkle and stir in the inoculant, and let them dry. If you are using the paper towel method of stratification, wait to do this until you’re ready to put the seeds in the substrate.
If you are using GA-3, apply it before you put the seeds in your paper towel or substrate. Read the directions on how to use the GA-3.
Seeds in Fruits:
To propagate seeds that are covered with pulp requires removing the pulp as it usually contains germination inhibitors. In nature, the fruit would be eaten and the seeds would later be pooped out. Using GA-3 usually has no effect on seeds with fruit.
What Substrate to Use
I use two types of medium or substrate. One when I sow the seeds into a tray for germinating and a different mix when I repot these into their separate, individual pots. No substrate is necessary when using the paper towel method. When sowing into the trays, I use equal amounts of peat moss, Perlite, Vermiculite, and potting soil. This mix is designed to have a high water holding capacity, allow for ample air space to maintain aerobic conditions, and allow the soil to hold onto food until the plant needs it.
When repotting from the germination tray, I use a mix of potting soil and Perlite in a ratio of 3:1, soil to Perlite. Certainly one could add peat moss and Vermiculite to this mix as well but in a lesser ratio than for the germination tray. While you want to give your plant the best possible conditions, you also want the plant to become accustomed to a “soil” environment.
Heat and Lights
It’s important to have the soil temperature at 70° regardless of the ambient temperature. With my set up, I have found that the Grow lights are sufficient heat to warm the soil in the trays, provided I adjust the height of my lights so they are close enough to the trays. If you have an area that is lighted sufficiently with natural light, then using the heat mats underneath the trays would be a good option. I found that using both is unnecessary. When I had both turned on, I put the mats on a timer so they would maintain the temperature at 70°. If the lights were on at the same time, the mats seldom needed to be on because the lights provided the proper temperature.
The Method of Sowing the Seeds in Substrate
Sowing into substrate requires a bit more explanation than the paper towel method. Once the substrate is mixed, I place it in the tray with the drain holes to about ¼” of the top and then place that tray into the one without holes. I sprinkle it with about 3 Tbsp kelp, mix gently, then tamp it down. To create a row for the seeds, I take a ruler and wiggle out a shallow “V” (1/4-1/2” deep) from short side to short side about 3” apart. They should be fairly evenly spaced and you should get about 7 rows to a tray. I then place the seeds uniformly inside the “V” but without any spacing like you would with vegetable seeds. The reason for this is that many native seeds are not “pure live seed”; some are viable, some are not. The crowding is OK just don’t layer the seeds, if possible. With the super small seeds, such as Heuchera richardsonii (Alumroot), you can’t be exact.
Once sowed, pinch the “V” together and tamp down. You do not want much soil on top of the seeds. If the seeds require light to germinate, I just sprinkle substrate on top and tamp down. It’s imperative that you tamp the soil as you want as much seed-to-soil contact as possible.
Remember to label the row. The easy labeling method is to use the first 3 letters of the genus and the first 3 letters of the species. For example, Gentian Alba would be GEN ALB. I keep a spreadsheet with each species that I sow; it shows the date I began stratifying them, the date they went to 70°, and the date they germinated.
When the whole tray is finished being sown, I water it in with a molasses and water mixture. It’s about 2 Tbsp molasses to 1 gallon of water, I just eyeball it. I do this to feed the microbes that are in the substrate and get the process started.
When to Transplant Seedlings to Individual Pots
I followed the advice in the books and transplanted to 2 ½” pots when four true leaves have developed. If you’ve had great success and most of the seeds are viable, you can have numerous plants tightly fitting in a row. I tease these apart and plant them individually. Hold the seedling by the leaves to protect the stem and roots. I sprinkle mycorrhizal into the soil to give them an added boost but often many will not make it.
Certain plants have long taproots and need to be transplanted into Deepots. Knowing the root structure (taproot, fibrous, rhizomes, stolons, etc.) of the plant you are propagating will help you to determine this. One site that lists this info for each plant is Critsite. It’s the only site I know of that lists the root structures but if you find others, please let us know!
Feeding and Watering
Check on your plants every day. Don’t assume they are doing fine. I made this mistake and never will again!!
When in the germination mode, I keep the soil moist, not saturated. Much like stratification, germination usually depends on sufficient moisture. Think in terms of nature, if there is a drought, many seeds are programmed not to germinate. This moisture also allows for the humidity dome to do its job. This dome also assists with keeping the moisture retained.
Once transplanted into separate pots, I water only when they need it and not on a rotational schedule based on the number of days since the last watering. I can usually tell if they need water by sticking my finger into the soil or picking up a pot. The pots are very lightweight when they are dry.
Feeding every 2-3 weeks is helpful. I use a hydrolized fish emulsion but only for those plants that aren’t being hardened off outside. For those outside, I use an odorless option; a simple compost tea that I make up from my vermiculture system. I also use this tea when I plant them into the prairies, woods, or savanna. Where we live, we need to consider the raccoons and skunks and not do things that will attract them.
This process is when you begin to transition the plants to an outdoor environment. A couple rules of thumb that I use to know when to do this: 1) the plants must be at least 2” tall, and 2) the nighttime weather needs to be above 40°. If I’m using the cold frame, I raise the lid during the day and lower it at night to maintain the solar heat that has built up from the day. If I’m using the garage, which ours is heated and never gets below 40°, I set the plants in an area that can get sunlight and keep the doors open during the day and closed at night. Eventually, I’ll move these plants outside during the day and back in during the night. I don’t let the plants in the garage or the cold frame get rained on during this time as I want to control the water.
I don’t rush this process and for some plants, they stay where they are and get overwintered rather than planted out. In general, it takes 2-4 weeks, but again, that is all based on the weather. I do not plant anything until the nights are consistently above 50°. When I decide not to plant the plants even when the temperature is favorable, I keep the cold frame lid raised and those plants in the garage stay on the deck unless there is a storm.
Whether you overwinter the plant or transplant it the first year is a judgment call based on how healthy and strong you think the plant is. After a few years of doing this, I’m convinced that many of them need to be overwintered and planted out as second-year plants.
The process I use for overwintering is to “plant” these in my vegetable garden. This was a very intimating process for me the first time I did it. I had babied these plants to this stage and now I was putting them out in the harsh elements of winter! It was difficult but I knew the natural process of freezing and thawing was necessary and eventually would strengthen those that made it through. And on that note, don’t expect that every plant will survive. It is what it is.
Once the vegetable garden is fully harvested, I dig sections deep enough to bury the tray with the pots up to the rim of the pot. Be sure the dirt is tamped down around these trays or individual pots if you don’t have a tray full. The soil is the insulator. Mark the corners with flags so come spring you know where to dig up your plants. Keep them moist. Once the ground freezes and the plants have senesced, cover them with a few inches of straw.
The first year I overwintered, I used a permanent black marker on my metal labels made from mini blinds. The marking wore off during the winter. To remedy this, I bought colored labels and now I color code my plants, making a list of what is being overwintered, how many of each, and what color(s) labels they have.
When spring arrives and the ground thaws, I remove the straw and place them in the cold frame, once again putting the lid up during the day and down at night if the temperatures are under 40°. If I have plants that have overwintered for twice, then I transplant them to the 5-6” pots once they begin to show their leaves. I want to be sure they have plenty of room for their roots to expand.
Planting Them Out
If you’re putting these into a native system such as prairie, savanna, or woodlands, you need to plan to water them once a week, unless it rains, throughout the growing season. I mark them with a flag and write the abbreviated name code on the flag with a permanent marker. Sometimes this writing wears off during the winter. I mulch around each plant, too. This helps to keep in the moisture and gives the plant some help with weeds that want to compete with the great soil and moisture. I’ll start planting after Memorial weekend and will plant up until the end of June if the weather is cooler and wetter. I will provide each plant with a drink of compost tea placed into the hole before I put the plant into it. Then I water the plant in once I have the mulch around it.
For the first growing season we make sure to water these plants each week that it doesn’t rain. Depending on the temperatures and whether the plants are in the shade or full sun, we’ll water every 4 days or 6-7 days. That’s something you’ll need to decide. Since we’re usually putting out quite a few, we use the pumper unit for watering. We had this created for prescribed burns but it’s a good thing for watering, too!
Keeping your equipment clean and sanitized is important. I do a washing at 2 different times during the growing season — after the initial transplanting and before I label for overwintering. In between the washings, I keep the dirty ones in a plastic bin; this way they are contained in one place and easy to move to the sink when it’s time to clean them. I wash them with a liquid detergent and brush, then rinse them in a 10% bleach solution, allowing them to air dry in the garage.
When completely dry, I either package them into lidded plastic containers or wrap them in a plastic garbage bag. By keeping up with this and storing them in a place where they don’t get dirty again. It’s so much more fun working with clean pots and having them ready when I need them.
Creating a Propagation Garden
I have established 3 propagation gardens (AKA prop gardens). These areas are where I put native plants I want to watch and from which I can easily collect seeds.
I found that a 2-year process makes for the best gardens. The first year, I mow very closely, then herbicide the area to kill off any weeds. If you have smooth brome in the area, be sure to use a grass specific herbicide as glyphosate doesn’t always kill them. You can optionally rototill at this point and then herbicide again. Once the area is dead, place 2 layers of cardboard down, making sure to overlap the edges of the cardboard, then add a fairly thick layer of plain wood chip mulch on top. I use cardboard instead of landscape fabric because I want it to break down easily and become a “natural” planting. I use plain wood chips because it weighs down the cardboard and keeps moisture in. Eventually you want your plantings to fill in and look like an intentional garden.
The second year is when I plant. I’ve found that because of the woodchip mulch I sometimes need to add some soil when planting so the plants are even with the top of the mulch. These plant also get a flag with their name written on it.
Having a cold frame sure makes the hardening off process easier! There are many sites on the web that can show you how to build one. It’s important to figure out where to locate it. We placed ours next to our house so it would stay a bit warmer. We also located it such that if I’m propagating shade and partial shade plants, I have the ability for that sun level in the end of the cold frame.
We did one extra step and made covers for it. Although it doesn’t hail in Wisconsin often, the possibility is there. These covers come in handy for winter use as well, serving to keep the weight of the snow from breaking the glass.
Bubel, Nancy. 1988. The New Seed Starters Handbook. Emmaus, PA: Rodale Press.
Cullina, William. 2000. Growing and Propagating Wildflowers of the United States and Canada. New York: Houghton Mifflin Company.
Deno, Norman C. 1993. Seed Germination Theory and Practice. Pennsylvania: Norman C. Deno. This has a couple of supplements that update the info and add new species to the original publication.
Heon, Al and Andy Larsen. 2003. Begin With a Seed. Newburg, WI: Riveredge Nature Center.
Phillips, Harry R. 1985. Growing and Propagating Wild Flowers. Chapel Hill: University of North Carolina Press.
Rock, Harold W. Prairie Propagation Handbook. Milwaukee: Wehr Nature Center.
Smith, Miranda. 2007. The Plant Propagator’s Bible. Emmaus, PA: Rodale, Inc.
Sperka, Marie. 1973. Growing Wildflowers: A Gardener’s Guide. New York: Charles Scribner’s Sons.