Seed Starting Schedule
When to Start Your Seeds Depends on Your Growing Zone
The first thing you need to know when deciding when to start your seeds is the last frost free date for your growing zone. In other words, when is the recommended safe planting date for your area? Once you know that, you can refer to your seed packages that tell you how many weeks it will take for each plant type to germinate and be ready for planting outdoors.
BUT! That time can vary depending on how much sunlight and supplemental light your seedlings are getting, how warm do you keep the seedlings (do you have a heating mat?), and are you diligently and properly watering your seedlings? It is best to keep careful records from the first time you start seeds indoors so you know whether your germination and growth period is fast or slow based on the environment you provide. The more heat and light, the faster it will all go.
Here are some basic guidelines for a variety of plants to get you started:
- 14 - 15 weeks: annual geraniums, gerbera daisies, pansies, violas, wax begonias, leeks, onions
- 12 - 13 weeks: dusty miller, fountain grass, impatiens larkspur, lobelia, celery
- 10 - 11 weeks: ageratum, candytuft, coleus, delphinium, dahlia, heliotrope, lavatera, leeks, onion, oregano, parsley, petunias, rudbeckia, scabiosa, snapdragrons, verbena, vinca, broccoli, cabbage, cauliflower, head lettuce, thyme
- 9 weeks: candytuft, cleome, dianthus, hollyhock, marigold, nicotiana, annual phlox, salvia, statice, sweet alyssum, peppers, eggplant, shallots, cherry tomato
- 5 - 6 weeks: agastache, amaranthus, aster, baby’s breath, bachelor buttons, calendula, celosia, cornflower, four o’clock, helichrysum, french marigold, morning glory, nasturtium, basil, beets, cabbage, chive, cilantro, cucumber, kale, melons, sage, squash, strawflower, tomatoes
- 3 - 4 weeks: cosmos, sweet peas, zinnia, beans, endive, pumpkins
Then allow an additional one to two weeks to harden off your plants.
Just a few other hints about specific seed needs:
- Some seeds like light to germinate, some like dark - check the package.
- Some seeds need to go through “winter” before they will germinate. Packaged seeds should be pre-treated.
- Parsley and tomato seeds should be soaked over night in warm water to aide germination.
- Lavender is tricky to germinate indoors. It needs to be pre-chilled then a month at 45 degrees.
- Morning glory seeds should be nicked with a razor or sharp knife before sowing.
- Large seeds should go right into larger seedling pots rather than plug flats. This would include sweet peas, morning glories, nasturtiums and melons.
There are thousands of different seeds, and many of them do have special needs. If you are planting more unusual seeds, particularly some of the perennial seeds, the may require special treatment. Check into it before you plant, and potentially waste, your seeds.
Start keeping careful records about your seeds to make it easier next year. Enjoy your plants!