Cold, gloomy days turn a gardener's thoughts to spring. Idle hands long to dig in soil and fuss over plants. Growing perennials from seed is a great way to get your gardening fix in the off-season. Starting plants from seed has other advantages as well. Native plants can be difficult to obtain. With seeds, you can choose from a wide range of species. Native plant societies, gardening clubs, and individual gardeners are all likely sources. Once the gardening season is in full bloom, you will get a great sense of accomplishment from the fact that you nurtured your plants from seed. In the meantime, here are some hints to ensure that your project is fruitful.
- Don't start your seeds too early.
- Time the growth of plants so that they will be large enough to move outside and survive transplanting in the spring.
- Follow seed packet directions with your region's last spring frost date in mind.
- Nature has developed mechanisms to ensure that seeds germinate at the right time. Most native plants, for example, need to be exposed to a period of cold. Seeds, such as those of black-eyed Susans, can be tricked into breaking dormancy by spending six to eight weeks in the fridge.
- Plants that need a deeper dormancy - for example, many native shrubs - require cold-moist stratification to germinate. Mix seeds with moist sand in closed plastic bags and refrigerate for one to four months.
- Moisture absorbed by seeds increases internal pressure, eventually rupturing seed coats and activating growth. The germination of seeds with thick or tough coats can be accelerated by scarifying, or scratching, their surfaces.
- Taking care not to damage the embryos inside, you can nick the coats of larger seeds with a knife to encourage water absorption. Roughen smaller seeds with sandpaper.
- Check package instructions for pre-treatment requirements.
- Any container that holds soil 2.5 to 5 cm deep may be used.
- Turn yogurt containers or milk cartons into plant pots by adding drainage holes.
- Choose a loose, well-drained, sterile planting mix. Commercial mixes work well.
- Before filling containers, moisten the soil so that it holds together when squeezed but is not dripping wet.
- Do not bury seeds too deeply - generally, at a depth twice a seed's diameter.
- Seeds that require light for germination, such as columbine or foamflower, should be sprinkled on the surface.
- Mist the soil surface and cover the container with a clear plastic lid or seal it inside a plastic bag to retain moisture.
- Once germination occurs and sprouts begin to appear, remove the cover.
- Seedlings require intense light. Promptly after germination, move seedlings where they can receive 12 to 16 hours of light. A large south-facing window is ideal. Insufficient light can be supplemented with fluorescent lights.
- Turn plant trays regularly to encourage straight stems. Mirrors or aluminum foil reflectors can be used to catch wasted light.
- Do not over-water seedlings - they need to be moist but not wet.
- Plants grown in seed flats should be transplanted to individual containers once they have their second set of true leaves. (The initial leaves are cotyledons, or food storage cells.)
- Hold the seedlings by their leaves, not their delicate stems.
- If grown in a planting mix without soil, seedlings will require fertilization once their true leaves appear. Use a weak solution of liquid organic fertilizer, such as fish emulsion, compost, or manure tea, once a week.
- Seedlings grown in a compost mix may not need additional feeding.
- Plants that have been sheltered from direct sun and wind need to be "hardened off," starting two weeks before transplantation.
- Place plants in a sheltered, shady area of the garden for an hour or so.
- Gradually increase the length of time the plants are left outside and slowly introduce them to direct sunlight and wind.
- Once the plants have adapted, transplant them to the garden on a cloudy day or in late afternoon. Planting them just before rain will give them a great start.