You can plant perennials, annuals and tender bulbs in the spring for summer flowers. Flowers planted in the spring can be sown directly into the garden from seeds or planted as transplants. Tender bulbs that have over-wintered indoors can be planted in the garden after all danger of frost has passed. All plants prefer a soil that is well-drained and sufficient in nutrients. It is preferable to amend your soil in the fall, prior to spring planting.
Perennial flowers have a life cycle of several years and are an economical way to add beauty to your garden. You can plant perennials as transplants or from seeds sown directly into the garden in early spring. Early planting allows the seeds to have sufficient bloom-time in the summer and fall.
Perennial flowers that can be planted in the spring include yarrow (Achillea), purple coneflower (Echinacea), columbine (Aquilegia), globe thistle (Echinops), blanket flower (Gaillardia), flax (Linum), penstemon (Penstemon canascens), evening primrose (Oenothera), lily of the Nile (Agapanthus), Mexican daisy (Erigeron), Thyme and flowering sage (Salvia).
The life cycle of annual flowers are short--lasting only one year--but the variety available expands your palette of summer colors and shapes in the garden. Use annuals to fill in gaps when other plants die off or have not yet sprouted. Annuals are used as accents in planters, as cut flowers or dried for arrangements. Michael N. Dana and B. Rosie Lerner at Purdue University Cooperative Extension Service state that most flowering annuals perform best when grown in full sun.
Annual flowers you can plant in the spring include ageratum (Ageratum houstonianum), magic fountain (Amaranthus), baby's breath (Gypsophila paniculata), bachelor's button (Centaurea cyanus), pot marigold (Calendula officinalis), Cosmos, forget-me-not (Myosotis scorpioides), geranium (Pelargonium x hortorum), morning glory (Ipomea purpurea), nasturtium (Tropaeolum majus), petunia (Petunia x hybrida), phlox, rudbeckia, scabiosa, sweet alyssum (Lobularia martitima) and zinnia (Zinnia elegans).
Tender bulbs refer to bulbs that can not over-winter in the garden. Tender bulbs must be dug up the fall and replanted in the spring, after all danger of frost has passed. Mary H. Meyer, Extension Horticulturist at the University of Minnesota Extension states that the time to dig up most tender bulbs is after the foliage has been killed by frost or has dried up.
Tender bulbs that can be planted in the spring include the hot water plant (Achimenes), peacock orchid (Acidanthera), windflower (Anemone coronari), tuberous begonia (Begonia x tuberhybrida), fancy leaved caladium (Caladium bicolor), calla lily (Zantedeschia), canna (Canna x generalis), gladiolus hybrids and dahlia hybrids.