Home Gardener's Annuals. Miranda Smith

       Petunias

       Tender

      Need warm weather; can’t tolerate any frost

      • Cardina cimber, Cypress vine (Ipomoea × mutifida, I. quamocit)

      • China aster (Caistephus chinensis)

      • Cockscomb (Ceosia argentea)

      • Coeus (Soenostemon scutearioides)

      • Cosmos (Cosmos bipinnatus, C. suphureus)

      • Dusty mier (Senecio cineraria)

      • Fanfower (Scaevoa aemua)

      • Fossfower (Ageratum houstonianum)

      • Fuchsia (Fuchsia hybrids)

      • Gobe amaranth (Gomphrena gobosa)

      • Heiotrope (Heiotropium arborescens)

      • Impatiens, New Guinea impatiens (Impatiens species)

      • ove-ies-beeding, Joseph’s coat (Amaranthus species)

      • Madagascar periwinke (Catharanthus roseus)

      • Mexican sunfower (Tithonia rotundifoia)

      • Morning glory, moonfower (Ipomoea species)

      • Nasturtium (Tropaeoum species)

      • Nemesia (Nemesia strumosa)

      • Rose moss (Portuaca grandifora)

      • Sapphire flower (Browallia speciosa)

      • Sweet potato vine (Ipomoea batatas)

      • Wax begonia (Begonia Semperflorens-Cultorum hybrids)

      • Wishbone flower (Torenia fournieri)

      • Zinnia (Zinnia species)

      • Zonal geranium, ivy geranium (Pelargonium species)

       Zinnias

       ANNUAL HARDINESS

      Annuals are categorized as hardy, tender, or half-hardy according to their tolerance to cool temperatures.

      Hardy annuals such as bachelor’s button, calendula, and larkspur grow best in cool temperatures and can withstand some frost and freezing. They are often started from seeds sown directly in the garden. In Zones 7 and colder, gardeners can sow hardy annuals outdoors as soon as the soil can be worked in spring. Some annuals can even be sown the previous fall. In Zones 8 and warmer, gardeners more often sow hardy annuals in fall for flowers in winter or early spring.

      Tender annuals such as impatiens, cockscomb, and zinnia are sensitive to cold. In most areas, they are started indoors and transplanted outdoors after the frost-free date, when the soil is warm. An indoor start is particularly important in areas with a short frost-free growing season.

      A third category of plants—half-hardy annuals—is accepted by some horticulturists but not by others.

      Half-hardy annuals are in between the other two types in terms of hardiness and include marguerite, lobelia, and petunia. Half-hardy plants like cool weather and tolerate a bit of light frost but are damaged by repeated exposure to frost and freezing. Gardeners in all but the warmest climates (Zones 8 to 11) start them early indoors and plant them out when frost danger is past.

       STARTING PLANTS FROM SEEDS

      Growing your own seedlings affords you a greater choice of plants and cultivars for your garden than purchasing plants from the local garden center. And seeds are much cheaper than plants sold by mail-order nurseries. You can sow seeds for hardy plants directly in the garden. But tender plants and slow-growing ones are often started indoors to produce plants that flower earlier than they would if sown outdoors.

      Before you plant any seeds, be sure the containers and tools you plan to use are clean because seedlings are easy prey for disease-causing organisms. If you are reusing starting containers, scrub them out with a 10 percent bleach solution, and let them dry before filling them with soil.

      Many people start seeds in a sterile soil mix or growing medium. A number of commercial seedstarting mixes are available, but you can make one from equal parts of peat moss, vermiculite, and perlite. Add two parts of fully finished, good compost to this basic mixture if you want the potting soil to supply nutrients for the first few weeks. Although compost is not sterile, it usually contains enough beneficial microorganisms to combat injurious ones.

       PLANTING SEEDS

      Most seed packets carry instructions for planting depth and spacing. A general rule of thumb is to plant seeds at a depth that is two to three times their diameter. Tiny seeds (those of begonias or snapdragons, for example) can be mixed with sand to help separate them and make them easier to handle; sprinkle this mixture on top of the potting mix. Most tiny seeds need light to germinate, so it’s important not to cover them after planting. When you mist the soil surface to water them, they’ll work themselves into tiny niches that will keep them moist. Plant larger seeds in individual holes, or make furrows as you do in the outdoor garden.

      Some gardeners cover their seeds with a thin layer of fine sphagnum moss to protect the seedlings from damping-off (a lethal fungal disease). Sphagnum moss has fungicidal properties. If you use it in your seed flats, make sure it stays moist at all times. When the moss dries out it becomes hard and stiff, and tender seedlings may have difficulty penetrating it. Although it was used to dress wounds during World War II because of its fungicidal properties, some people experience skin irritations if it gets into cuts or scratches; wear gloves when you work with it.

      Temperature. The best temperature for germination varies from plant to plant. Generally speaking, tender (frost-sensitive) plants usually sprout best in warm temperatures of 70° to 75°F. Cool-season flowers germinate better in cooler temperatures around 60° to 65°F. Some plants need a period of freezing or cooling at temperatures of 35° to 40°F before they can germinate. Seed packets often supply this information.

       Sow seeds that are large enough to easily handle one or two at a time into flats, cell packs, peat pots, or other containers of moist potting mix.

       Carefully cover seeds that don’t need light to germinate by sprinkling fine, loose, moist potting mix over them to the correct depth.

      Light. Seedlings need plenty of light as soon as they break through the soil surface. Fluorescent fixtures are the best way to supply light for indoor seedlings. Their light is very even, and the plants don’t need to be turned to grow straight. You can use special “grow light” tubes, full-spectrum daylight lamps, or a combination of warm white and cool white tubes. Set the lights on a timer so they’re on for 16 hours a day. The tops of the seedlings should be no more than 3 or 4 inches below the lights for the first couple of weeks; later you can gradually raise the lights to 5 inches above the leaves. Start out with the seedling flats elevated on some sort of stand that can be gradually lowered as the plants grow taller. (A pile of books works nicely.) Or suspend the light fixture on chains