Seed collecting and germination

Columbine seeds

Start collecting seeds now for next year’s pollinator garden!

In addition to maintaining a number of existing pollinator gardens in the watershed, FLOW leads the way in the creation of a few new gardens every year. While we initially sow those with a purchased seed mix, we may also supplement these gardens with mature plants that FLOW volunteers have started from seed. Sometimes we do this to increase the diversity of an established pollinator garden, or to jump start a garden that’s been recently seeded and is slow to fill in. To achieve this, several of our volunteers collect seeds to prepare for nurturing at home.

Although it’s midsummer, it’s not too early to start collecting seeds from some of your favorite plants that may have already reached peak blossoming and are setting seeds. Careful observation is needed to catch that sweet spot between green seeds and mature seeds that have already fallen to the ground. (Of course that’s if hungry deer have even allowed your plant to bloom!)

Be sure to practice good habits when collecting from outside your own garden. Ask permission of landowners, and only collect a few seed heads from any one plant. A couple of seed heads can go a long way! Paper lunch bags are a great way to collect; you can shake the plant into the bag, or snip a few heads and drop into the bag for later cleaning. Label with the species and location and date where collected.

A great source for information is Prairie Moon Nursery (prairiemoon.com). Not only can you purchase a wide variety of native seeds and plants from them, they provide excellent info for your own seed starting efforts. Their photos of seeds that show their scale will help you determine if you are collecting seeds or merely fluff. Some native seeds such as great blue lobelia and cardinal flower have extremely small seeds that are easy to overlook.

Once you have collected seeds, you can sow them with the fluff, but it’s better to clean them for easier storage, to eliminate any insect eggs, and improve germination. Here’s some info on collecting and cleaning from the Xerces Society. FLOW uses a set of sieves similar to what’s shown on page 6 for seed cleaning. Milkweed seeds can be especially challenging to clean – they fly all over the place! One trick is to put the seeds with fluff in a paper bag, add some coins or other objects, and shake vigorously to separate the seeds from the fluff. If you are brave, you can use fire to burn the fluff, as shown here on YouTube.

Essential to the next step of your homegrown native plant nursery is determining the germination code (also part of Prairie Moon’s plant info). Germination codes run from A to O and classify plants by the stratification or other preparation needed for germination. Stratification is the period of moist cold a seed needs to germinate. This period can run from 30 to 120 days, depending on the species. Some species need additional cycles of warmth and cold, spanning one to two years before they germinate. Nature’s way is to drop seeds on the ground, where they will lie dormant until the next spring, after winter’s cold and snow. However, those seeds have to overcome several obstacles: they have to fall on bare soil but not get washed away, blown away, or be eaten by animals! Collecting and germinating seeds will not only ensure greater success, but allow you to control where the plants end up.

FLOW encourages planting native species; many of the seeds we have packaged to give away at our information tables are germination code A, which requires no stratification. These species can be planted in the spring with good success.

For plants with stratification needs, there are several ways to prepare seeds.

FLOW volunteers use a couple of different methods – inside (artificial stratification) or outside (winter sowing).

Ready for the fridge

Inside: Damp sand or soil is mixed with seeds and kept in the fridge (not freezer) for the required period of time. Some use damp paper towels or coffee filters folded over the seeds, in plastic bags. After the required number of days in the cold, the seeds are ready to plant. Some seeds such as milkweed may need additional preparation, such as an overnight soak in warm water, or a little nick (scarification) with clippers to break the seed coat. The bags do need to be checked for mold or dryness during their time in the fridge.

If the chance of frost has passed, they can be planted outside, but better control and success comes with inside germination. Grow lights and heating pads are used to provide an ideal early start. Once seedlings start to show true leaves, they can be potted up in regular pots or space saving “cone-tainers” and moved outside for continued growth. Depending on the time needed, your seeds may be in the fridge some period of time between mid-November and March. If sowing indoors, aim to start in mid-March.

Detailed guides for the best methods for each germination code can be found here: https://www.prairiemoon.com/how-to-germinate-native-seeds.html

Seedlings ready to go outside

Outside: “Winter Sowing”

For those who want to devote their kitchen appliances to food, “winter sowing” is a way to get a head start on plant germination, without the space requirements needed for inside storage and seeding. To winter sow, containers (commonly milk jugs, but other containers can be used) are slit open, drain holes are added, then they are filled with several inches of soil. Seeds are added, either surface sown or lightly covered with soil, depending on the seed’s requirements. The tops of the milk jugs are left uncovered, to allow for snow and rain to keep the seeds moist. After seeding, the sides are closed up with duct tape. This can be done as late as January; allow 8 weeks before the last frost day in your area. If unseasonably warm weather arrives, they may need to be unsealed to avoid overheating; occasionally watering may be needed, but in general they provide a low maintenance, protective mini-greenhouse. Once warm weather arrives to stay, they can be unsealed and potted up into regular pots or garden spaces as time and seedling growth permits. Some species that have done well for us using this method are Baptisia, mountain mint, great blue lobelia, rattlesnake master, wrinkle leaf goldenrod, golden alexander, foxglove beardtongue, swamp milkweed, royal catchfly, downy and early sunflowers, prairie blazing star and evening primrose. Some other species such as butterfly and common milkweed have not done very well via winter sowing, but do quite well if stratified and grown inside. Try your favorite species both ways to see which works best! And if you would like to help FLOW by starting plants for our gardens, please let us know!