A reasonable schedule in zone 6b might be to start perennials, herbs in the mint family (many of which are perennial), and anything the packet says takes longer than eight weeks to reach transplant size, in late February (Feb. 25th for me). Start annuals with six-to eight-week maturing periods in March (March 10 for me). Start quick (2-3 weeks) annuals and vegetables, that will only get leggy indoors, in early April (April 1st for me). Also, you can do succession sowing to get later swaths of zinnias, marigolds, salvias, snapdragons, etc., ready to flower in late summer, as late as the first week of May. The reason for sowing anything in flats that can be sown directly is to get size on the plant, and make it less vulnerable. Corn is a good example—a sprouted kernel to a squirrel is just a snack with leaves attached, that need biting off. If you grow your corn in pots until the kernel is used up, and the roots are strong, you may get a harvest for yourself.
Last year I got too eager to grow things, and started perennials in January. I was also trying to use a potting medium instead of peat pellets, and it messed up my germination rate. I don’t find it as easy to go peat-free as the TV garden shows imply. The peat pellets’ advantage is that they’re resistant to fungus, and the protection they offer lasts a long time, until the seedling has grown past the danger of wilting. Also, they can hold moisture without heaviness. Heavy damp stresses seeds for oxygen, and more humus-y mixes retain cold, both inhibiting factors to germination and survival. Last year, many of my seeds never germinated at all.
Another problem with keeping plants indoors too long is the artificial environment. Indoor air is stagnant, allowing a foothold to disease, fungus gnats, and mites; plants need air movement for transpiration, the release of moisture through the pores in their leaves, which encourages the root system to draw moisture from the medium. In fact, a fan running in your growing room, at low speed, is a good idea.
The time when your plants are large enough to go outdoors should coincide well with the change in weather, from winter cold to spring daytime temps in the 60s and 70s. Find a shaded space with wind protection, or create one. Perennials should be first out; once they can stand on their own in full sun, and especially with the benefit of a few rains, you can take them out of circulation—either plant them, or at least place their pots where you intend to plant them. A number of perennials, such as coneflower, salvia, achillea, rudbeckia, monarda, and foxglove, have hairy, rumply, or ferny leaves, a sign that they’re adapted to frost tolerance.
Frost, also, harms hardy plants less after the equinox (March 20, 2023)—when daytime length equals night. Nighttime temps in zone 6b are usually above freezing. The ground warms up, and the hours of frost needed to burn leaves and harm roots are not available. Observe which plants already in your garden are pushing up strong new growth; the same plants from this year’s starts will survive through frost, if you have them well hardened.
(to be continued)