UNITED STATES—Winter continues. It will not end until March 19. Wintry weather is unconcerned with such dates though. It could end at any time, or continue a bit later. Vegetation is more aware of this than we are. It wants to be ready regardless. Cool season annuals linger as long as they can. As they no longer can, warm season annuals should be ready to replace them.

Warm season annuals, or summer annuals, include both bedding plants and vegetables. They perform seasonally as cool season annuals do, but through warm seasons instead. They perform for only one annual cycle, although several have potential to be perennial. Removal of perennials is necessary only because subsequent annuals need the space.

All sorts of annuals are available in cell packs from nurseries. They become available as they become seasonable. Those that bloom for late winter and early spring are available now. More of those that bloom best during warm weather should become available soon. It is still a bit too cool and early for most of them. It is not too early for their seed, however.

More varieties are available as seed.

Although plugging cell pack seedlings into a garden is easier, some prefer to sow seed. Those who do so should begin about now so that the new seedlings are ready by spring. Many seedlings require the warmth and shelter of a greenhouse to grow. As they mature, and the weather warms, they relocate into their garden. Other seed prefer direct sowing.

Many more varieties of annuals are available as seed than as seedlings from nurseries. Even if only a few varieties of seed are in nurseries, countless more are available online. Also, some flowers from previous seasons provide viable seed for subsequent seasons. There are a few reasons to justify the extra effort of growing annual seedlings from seed.

Sunflower and nasturtium are among the warm season annuals that prefer direct sowing. Their roots dislike confinement within cell packs. They recover slowly from transplanting. Cosmos and alyssum do not mind transplanting, but also grow easily from direct sowing. Seed for many varieties can start now because the weather will be warmer as they grow. Petunia, impatien, zinnia and lobelia are easier from cell packs later.

Highlight: New Guinea Impatiens

Busy Lizzie had been unavailable for years because of a downy mildew epidemic. It has only recently been regaining availability and popularity. During its absence, New Guinea impatiens, Impatiens hawkeri, became more popular. Although a closely related species of the same genus, the two are actually very different. Resistance to mildew is important.

Besides that, New Guinea impatien is about as foliar as it is floral. Its bolder and slightly bigger flowers are notably less abundant than those of busy Lizzie. Also, its floral color range is limited to white, pink, red, lavender, magenta or orange. Its rich green or bronze foliage below compensates though. Many cultivars are variegated with yellow or salmon.

New Guinea impatiens are unfortunately a bit more expensive than most other annuals. The smallest that are available are in four-inch pots. They are unavailable in smaller and less expensive cell packs. They can grow about a foot wide and slightly taller if crowded. During winter, they deteriorate; but they can be tender perennials with shelter from frost.

Tony Tomeo can be contacted at tonytomeo.com.