|When Should I Start my Seed?|
Good timing in sowing seed is a key to having transplants of the right size to set out in the right weather. You need to determine four different things in deciding when to plant your seed:
You can ask your local county extension agent for the frost dates and other seasonal benchmarks for your area. You can also find this information in publications like the Farmer’s Almanac, and on many internet websites by searching for "US Frost Free Dates." And, of course, recommendations about when to start your seed are included for every listing of individual plants in our Flowers or Vegetables section . So watch your calendar carefully – if a seed is supposed to be started 6 to 8 weeks before final frost, don’t start it four weeks or ten weeks before. Immature seedlings started too late will not be large or strong enough to move outside when it’s time, and those started too early will be too tall, lanky or progressed to transplant well. Seedlings are best transplanted before they are in bud or flower!
The second issue in timing your seed starting refers to the preferred temperatures for the kind of plant you are growing. Some like the cool temperatures of spring and fall (the cole crops of Cabbage, Broccoli , and Cauliflower, and flowers such as Snapdragons, Pansies and Primulas) while others will do nothing until long days and hot temperatures prevail (many summer vegetables such as corn, beans, squash, okra, and flowers such as Vinca, Zinnia, Marigold, Asclepias and Sunflower).
Please also refer to the Vegetable and Flower sections for information about the third factor: the number of weeks it takes for a seed to germinate and grow to setting-out size. You should use this information to determine what the right date for setting out is in your area. Simply take this date, then count back the number of weeks it will take to grow garden-size transplants.
Finally, you should consider the classification of the type of plant you are growing from seed – is it a member of the annuals, herbacious perennials, house plants or biennials?
Annuals – These are plants that complete their life cycle in the same year their seed are sown. They grow, flower and set seed all in one year. For American gardens, we treat as annuals those plants that are perennial in their native tropical habitat but that do not survive the winters of our climate. Salvia splendens is grown like an annual here in the U.S., though it is perennial in its native Brazil. Annuals are started indoors or in seed beds outdoors, depending on the type of plant. Most are frost tender, and should not be planted outside until all danger of frost has passed (you can learn of this date from your local Extension Agent or the Internet as mentioned above). Some annuals are hardy, which means they may be sown in early spring as soon as the soil may be worked and they will not be killed by frost. The information to "sow outdoors in early spring" is given in the individual listings.
Herbaceous Perennials - We use this term to describe plants that live more than two years; they will die back to the ground each year but come back the next year. Some herbaceous perennials are very long-lived, and some come back only a few years, depending on the genetic propensity of its genus and /or species. Perennials are best started in spring or summer up to two months before frost so the plants will be mature enough to plant out into their permanent location before cold fall weather sets in. Hardy perennials and those requiring stratification are often sown outdoors in late fall or early winter for spring germination.
House Plants -The name is pretty self-explanatory! Almost any kind of house plant seed may be started indoors at any time of year.
Biennials – These plants have a two-year life cycle. In the first year, you start the seed, set out the plant and it begins growth. The second year, it matures, blooms and sets seed, and then dies. Foxglove and Hollyhock are two well known biennials. Like perennials, biennials are started in spring or summer up to two months before frost and planted out before cold weather.
NASA Seeds in Space
"Vines provide a distinct ornamental touch; while their versatility in size, texture, color and bloom time artfully blends architecture with the landscape," Natural Life, Guide to Landscape Plants-Second Edition.