As the days get longer and indoor plants begin to produce new shoots, indoor gardeners often get antsy and start looking for something – anything! – they can do to activate their green thumb. And that often includes sowing seeds too early.
Remember the old adage “slow and steady wins the race”? Aesop was obviously a gardener! Seeds have to be started at just the right time to give the best results. Yet, the opposite seems so logical! if I sow my tomatoes (or my petunias or my peppers) earlier that I’m supposed to, won’t I get faster resultst? Nope, you won’t. In fact, quite the opposite.
I get plenty of emails from people who want to know what to do about their cucumbers (just an example) that are scrambling all over their living room and beginning to bloom long before the frost is out of the ground. These overgrown plants will never fruit or bloom well indoors, yet when you finally can plant them outdoors, they just collapse. Ideally, seedlings should be young and vigorous when you plant them not, not yet in flower or even in bud. In fact, if anything, it’s better to sow seeds a bit late than a bit early. Experienced gardeners have already learned that sowing seeds too early is a mistake; it’s the neophytes who, in their enthusiasm, get going too soon in the spring.
Right now, in early February, the days are still too short for seeds to do well in front of a window except in the tropics and subtropics. The few seeds that need early sowing indoors prefer begin grown under fluorescent lights where you can provide 14 to 16-hour days..
The following are among the (very rare) seeds to sow in early February:
Tuberous begonia (Begonia x tuberhybrida) (warning: keep lighting under 15 hours for this one)
Canterbury Bells (Campanula medium)
Double datura (Datura metel) (but sow Datura stramonium direct in the garden in May)
Fairy Snapdragon (Chaenorrhinum organifolium, syn. C. glaerosum)
Dame’s rocket (Hesperis matronalis)
Laurentia (Laurentia axillaris or, more correctly, Isotoma axillaris )
Perennials that require a cold treatment to germinate (Aconitum, Agastache, Anemone, Astrantia, Dictamnus, Delphinium, Gentiana, Helleborus, Helianthus, Hibiscus, Kniphofia, Lilium, Maianthemum, Eryngium, Paeonia, Primula, Scabiosa, Thalictrum, Trollius, etc.)
Cold Treatment: For these special plants, sow the seeds in February in a pot of damp growing mix, seal the pot inside a plastic bag and place it in the fridge. In mid-March or early April, expose the pot to light and heat to stimulate germination. Note also that temperate-climate trees, shrubs and evergreens almost always need a cold treatment to germinate well.
Note: The list above was developed for Northern gardeners (hardiness zones 3 to 6), that is, for a climate where planting outdoors usually begins in late May or early June. For readers who garden in more temperate regions, I suggest you consult a specialist in your area about what to sow in February.