Handling Seed and Pre-Treatment
Seeds are alive. They are a magical combination of “quiet rest” and “aliveness,” this incredible packaging has allowed wild plants to survive and multiply through thousands of years, and to rebound after fires, floods, cold winters, and so much more. This combination of traits also requires a little bit of care on your part to help your seeds germinate and survive.
First, always store seed out of direct heat (such as enclosed vehicles on a sunny day). The best way to store seeds until you are ready to plant is in a cool, dry, dark place. (Refrigerators are great).
Second, some of your seeds may be ready to immediately germinate, however native seeds are often dormant, meaning they have physical or chemical properties that inhibit germination until conditions are optimal for growth. To make matters even more complicated, some plants produce both seeds that are ready to germinate and some that are dormant and will not germinate until their dormancy is switched off. This is very different from garden vegetable seed, which is bred to have immediate and fast germination rates. Native seed can be SLOW to get started.
Our general rules of thumb for planting success are:
- All native seed is best planted outside in the fall. Both ready to germinate seeds and dormant seeds will typically germinate best in cool weather (cold weather exposure switches off the dormancy of many seeds).
- Seeds can be successful spring-planted (especially annual species), however, keep in mind that spring-planted wildflowers and grasses usually need supplemental irrigation to get them established throughout the first growing season. (Another advantage of fall-planted species is that they get much of their water needs supplied by winter precipitation developing good root systems before things begin to dry out in late spring).
- If you are not fall-planting, you should “cold stratify” your seeds in a refrigerator for 2-weeks prior to planting. This will switch off the dormancy for many species, allowing them to germinate when exposed to light, ample moisture, and warm soil. In the case of seed mixes that you intend to direct sow, you can mix the seed with damp sand prior to refrigeration for even better germination.
- Some seeds also benefit from pre-soaking in warm water for 2-days prior to planting (following cold stratification). In particular we recommend this approach with showy milkweed (which is a notoriously finicky species), lupine, barestem biscuitroot, blue-eyed grass, cow parsnip, mule’s ears, irises, columbine, and native clovers. When pre-soaking, we recommend changing the water 3-4 times daily during the pre-soak period, then directly planting the seed.
Please know that there is an element of mystery with many native species, and the exact germination protocols for some plants are not well understood.
Direct Seeding or Growing Transplants?
Our seed mixes are best planted directly in the ground, in the fall, or in the spring following cold stratification for 2-weeks in the fridge (followed by ample irrigation after the mix is planted).
For single species packets, you may want to grow them in containers for later transplanting. In particular, small, fragile, and slow growing species are often best started in containers where they face minimal competition from weeds or faster growing native grasses and wildflowers. We typically have the best success growing species such as blue-eyed grass, springbank clover, camas, Douglas aster, checkermallow, showy fleabane, sea thrift, milkweed, irises, and columbine as transplants.
Some of the species that tend to do well from direct seeding include yarrow, lupines, meadowfoam, and all types of clarkia.
Site Preparation and Direct Seeding
When planting native grass and wildflower seed, we recommend sowing on bare, weed-free ground following extensive site preparation to reduce as much dormant weed seed as possible.
Our preferred method for preparing new wildflower meadow areas is to cover newly cultivated areas with opaque tarps or black plastic for a full growing season before planting (a full calendar year is even better). We’ve prepared up to ½ acre for planting this way in a single season, and with careful treatment, large tarps or plastic sheeting can be re-used over multiple seasons to cover new areas – slowly increasing the size of wildflower plantings year after year.
When planting native seed, we recommend you hand scatter it directly onto the soil surface. Do not bury the seed or cover it with soil, however it can be lightly raked into the soil after planting. We recommend planting in the fall to take advantage of natural winter precipitation, however spring planting can also work. Note that the later into spring planting occurs, the more irrigation plants will need throughout the remainder of the growing season to get established. Fall-seeded plants usually don’t require any supplemental irrigation.
IMPORTANT INFO ABOUT PLANTING MIXES – PLEASE READ
Please note that the seed size for many of the plants we sell is extremely small! A single tablespoon might hold several thousand seeds of some plants such as Western Yarrow, Farewell to Spring, and even some of the native grasses.
While we formulate our mixes at robust seeding rates, the small seed sizes results in a relatively small volume (at least if you were expecting seed the size of lima beans!).
To efficiently spread a seed mix over a large planting area, we strongly recommend that you “bulk up” your seed mix with an inert material to increase its overall volume. We use an organic granular plant-based cat litter ourselves, but other people commonly use vermiculite, sand, corn meal, or dry non-clumpy soil.
To do this, we recommend mixing the seed and inert bulking material together in buckets, wheel barrels, or plastic totes. Ideally, try to at least add 2 to 3 times more inert material to increase the volume of the seed mix. Carefully combine all the material, and mix extensively until the seed is held in a solid suspension with the inert ingredients. It’s also a good practice to include slug bait to reduce damage from invasive slugs. (Iron-phosphate slug bait is safe for people and pets, and is organic-approved).
Once mixed, the seed can be hand scattered (like chicken feed) over the planting site. We recommend dividing your materials into at least two equal batches. Spread one batch over the entire planting area while walking back and forth. Then scatter the second half over the entire site again, walking back and forth, this time perpendicular to your first paths. As you do this, it’s a good idea to shake the mix periodically to ensure the seed remains evenly distributed in the mix.