Q: I’d like to grow flowers from seed for my summer garden. How can I get started?
— Linnea Phillips
A: Growing flowers from seed can be a rewarding way to keep color in your garden, and this is a good time to begin germinating seeds. Growing plants from seed can give access to a wide selection of colors and varieties and also save money.
Seeds of many summer flowering plants need soil temperatures of around 70 degrees Fahrenheit to germinate, so they are usually started indoors and then transplanted into the garden. Flowers that could be started now include impatiens, poppies, cosmos and columbine. Some perennial plants, like hollyhocks and Gaillardia, are seeded now but will not bloom until next year because they require a chill to set flowers.
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Buy good quality seeds and carefully follow instructions on the packet, as optimal levels of light and temperature vary. You will need flats or other clean, well-draining containers — even pierced waxed cartons will serve if cleaned with a 10 percent bleach solution. Plant seeds in a sterile potting or seed-starting soil or a mix of sphagnum peat moss and vermiculite. The ideal soil medium is light, sterile, and able to retain moisture yet drain well.
Some seeds are very sensitive to temperature and will not germinate unless kept within a preferred range, so containers may need to be artificially warmed by lights or another heat source.
Water your planted seeds once and cover them with glass or plastic that does not touch the planting medium. The cover is removed when the first sprouts appear. Then use a mister to keep soil damp without harming delicate sprouts.
After germinating, sprouts are moved to a cooler, bright location (out of direct sunlight) like an indoor window. When their first true leaves appear, the young plants are hardened off in outdoor shade and then transplanted into the garden. If sprouts are in a flat, they will need to be transplanted to individual containers to have room to grow.
Master Gardeners can give more information on this process of starting flowers from seed.
Got a gardening question?
Contact the University of California Cooperative Extension Master Gardeners at 781-5939 on Mondays and Thursdays from 1 to 5 p.m. in San Luis Obispo; at 473-7190 from 10 a.m. to noon in Arroyo Grande; or at 434-4105 on Wednesdays from 9 a.m. to noon in Templeton. Visit the UCCE Master Gardeners Web site at http://ucanr.org/sites/mgslo/ or e-mail firstname.lastname@example.org.