Nurseries offer young seedlings of both annuals and perennials, giving you a head start over sowing seeds yourself. Frost-tender summer annuals, such as marigold (Tagetes) and petunia, and warm-season vegetables (tomatoes and peppers, for example) should be planted after the last spring frost in your area. Hardy annuals, including pansy (Viola) and calendula, and cool-season vegetables like lettuce and broccoli can be set out 3 to 4 weeks before the last-frost date. They also can be planted in late summer, for flowers and vegetables in fall or (in mild climates) in winter. Plant perennials purchased in pots or cell-packs in spring or early fall.
At the nursery, choose stocky plants with good leaf color. It may be tempting to buy plants already in bloom, but younger ones perform better in the long run. Be sure to keep the plants moist until you're ready to set them out. Prepare the soil as you would for sowing seeds; at planting time, it should be moist but not soggy.
Removing plants from small containers
From cell-packs. Turn the cell-pack upside down and poke plants out by pushing with your thumbs on the bottom of each cell.
From pots. Turn individual pots upside down, holding the plant between your fingers. The plant should slip out easily.
From flats. Use a putty knife to separate the plants in the flat by cutting straight down around each one.
Plants in peat pots. Note that plants in peat pots receive a slightly different treatment. They are not removed from their pots, but go into the ground pot and all; the roots then grow through the pot into the soil, while the pot ultimately decomposes and disappears.
Make sure the pots are moist before planting by letting them stand in a shallow container of water for several minutes. If they're dry, they'll absorb moisture too slowly from the soil and the roots may be slow to break through them, resulting in a stunted plant.
It's also important to cover the tops of the pots with soil, since exposed peat acts as a wick to draw moisture from the soil. If covering the pot would bury the plant too deeply, break off the rim to slightly below the soil level inside the pot.
1. Dig a hole for each plant, making it the same depth as the container and an inch or two wider.
2. With your fingers, lightly separate matted roots. If there's a pad of coiled white roots at the pot bottom, cut or pull it off so that new roots will form and grow into the soil.
3. Place each plant in its hole so that the top of the root ball is even with the soil surface. Firm soil around the roots; then water each plant with a gentle flow that won't disturb soil or roots.