Starting Plants from Seed

  • Propagation from Seed

When propagating, it really pays to think like nature. Pay careful attention to the conditions that the parent plant was growing in—the sun or shade exposure, the soil and duff or litter layer, the moisture in the area, and if possible, the phenology of the plant throughout the seasons. Then think about what happens to those seeds in the wild. Think about the natural conditioning processes that occur to plants and their seed in the native environment.

Many seeds have built-in mechanisms that prevent germination until ideal conditions are met. Even when perfect conditions are met, some of the seed bank of a species will not germinate. They will wait, often camouflaged in the duff, as an insurance policy against a possibly disastrous growing season.

Would it make any sense for the seed to germinate right away, or will conditions be better for growth in another season? Seeds do not necessarily hit the ground at the best time for them to germinate. Some seeds germinate more readily when really fresh, while others need to be “dry-conditioned,” (which is what we’re doing while cleaning and storing). What changing conditions are the seeds subjected to while they wait for optimum conditions for germination? Are the seeds encased in fruits that are food for some creature? These types of seed need a prior experience—an intermediate step—in order to germinate.  

Seeds are of two basic and very different types: Most are orthodox which means that they need to dry out completely before they will germinate, or they are recalcitrant, which means that they quickly deteriorate when they are too dry. It’s a pretty amazing thing because a living plant is about 95% water, but the orthodox seed when fully dried is only 5% water. The recalcitrant seeds are mostly the nuts such as acorns, buckeyes and bay nuts; they are viable as a seed to sprout for just a short period of time—until they dry out naturally. If they are stored, it is often in an altered form (maybe ground into a meal) for the food value.  

Heat map setup

My grow-light setup with a heat mat.

If you have room indoors to set up an indoor system, with a grow-light and a propagation or heat mat, you can get plants started that usually germinate in warm weather, and you can get a head start on the season for edible plants, ornamentals, and some native perennials. The propagation mat will bring the soil temperature up to about 70 degrees, which will speed up seed germination rates and root growth.

Do not, however, place the seedling flats or pots directly on the heat mat; raise them above it about one inch using a baker’s rack or 1” x 1” stakes.  Otherwise you will be “cooking”  the root system!   

Not all seeds need light to germinate, but all seedlings need light from directly above to grow well. A grow-light set-up that allows you to adjust the distance above your containers is best. To germinate seeds, put the lights about two inches above the container.  When the seeds have germinated, lift the lights to make sure that tender young leaves are not being burned. Put your grow-lights on a timer; most seedlings need 12 to 14 hours of light daily.

Depending on the species I am working with I may use a light barrier, such as a piece of newspaper or burlap or a plastic lid, to really increase the heat and moisture. Situations like this can encourage mold and mildew to grow; a neat little trick is to sprinkle ground cinnamon on the soil. Cinnamon is a natural anti-fungal, and it also smells great!

When germination starts you will want to monitor the growth closely. Remove a light barrier just as the seeds start to germinate and before they put on growth that could be crushed, and if you have a plastic cover over your seedling flat, you’ll need to make sure it does not get too hot for the delicate new seedlings. Sometimes I remove the cover during the “daylight” (when the grow-lights are on) and replace it in the “night” time (when lights are off).

When watering new seedlings I always use water that is at the ambient temperature, and if it’s tap water I fill bottles ahead of time so that any chemicals in the water can off-gas prior to using the water on my seedlings.  

The seeds of many native perennial plants can be sowed in flats in the late summer or early fall, watered in once, and then left in a protected place outdoors to experience the changing day lengths and temperature fluctuations. If the rainy season is normal you just have to keep a watch for germination; if not, you will need to water periodically. Some native perennials take months to germinate, so be patient!   

Growing Milkweed From Seed

Milkweed for the Monarch Butterflies

Asclepias fascicularis
Milkweeds provide important resources for many beneficial creatures, including Monarch butterflies. The fine leaves of this native milkweed gives it’s a soft, wispy look. The plant isn’t long-lived, but reseeds itself readily. Summer blooms, 3’ tall, low water, full sun, dormant in winter.

Seed Eaters

A number of animals store acorns for later consumption; notably the Acorn Woodpeckers with their ‘granary trees’. They place each acorn just so, packed tightly into a hole, and then tend to their store regularly, moving the acorns to smaller holes when they start to dry up and shrink.

Natives for a Meadow Garden

Some of my favorite annual wildflowers are the gilias, and the whole genus is pretty much deer-proof. I like globe gilia (Gilia capitata) with its round heads of small blue flowers; these grow wild on Mt. Burdell. I haven’t seen bird’s-eye gilia (Gilia tricolor) in the wild in Marin, but I sure love it in my garden. It does fine in the ground or in containers, and the intricate coloring of the delicate flowers is a true marvel. Even more marvelous is the turquoise pollen!

Transplanting Tips

If you are working with old seed you can do a simple viability test before sowing.  Use a damp paper towel, lay ten seeds onto one-half of the towel, fold the other half over, and keep moist. Watch for the development of the radicle; the number of seeds that germinate will give you a rough percentage of viabilty of your seed.

Creating a Meadow Garden

The days are still warm and we’re all hoping, once again, that this will be an El Niño year with ample rainfall and a good snow pack in the Sierras. The days are noticeably shorter, and the evenings are much cooler. The shorter day length is a cue to many native plants and seeds that the season of growth in California is arriving; now we just need the rains!

How Does a Seed Form?

The flowers of a plant are designed for the purpose of making seeds. If a flower is pollinated, then fertilization can take place, and a seed develops in the ovary of the plant. This is sexual reproduction, and ensures genetic diversity. As the fertilized seed develops, so does the fruit (pome, pod, or capsule, etc.) which surrounds the seed.


Helping Seeds Sprout

Some seeds have built-in mechanisms that prevent germination until ideal conditions are met. Even when perfect conditions are met, some of the ‘seed bank’ of a species will not germinate. They will wait, often camouflaged in the duff, as an insurance policy against a possibly disastrous growing season.

Some Natural Types of Seed Pre-Conditioning

Whenever I'm out collecting I always keep it foremost in my mind that seeds are food for all sorts of insects and other invertebrates, for birds, rodents and other mammals, and food for humans!

When I gather toyon berries in December, I take just a handful from each cluster, and go to several different shrubs to collect. I want to make sure there’s still plenty of food for the birds; the red berries are a magnet for cedar waxwings, robins, house finches, band-tailed pigeons and the mockingbirds. By February, there are no more berries on the toyon.


I’ve always had a fascination with fecundity; a desire to make more of something, especially when an  abundance of possibilities is so obvious.  Plants offer so many opportunities to be fruitful. Now, with plenty of space at our new nursery, and access to gardens full of ‘mother plants’, I can indulge my every urge to be prolific and productive!