Each spring home gardeners buy bedding plants (annual flowers and vegetables) from local garden centers and greenhouses. To help ensure a successful start to the gardening season, select strong, healthy plants and harden them outdoors for a few days before planting. Proper planting is another key to success.
Select short, stocky plants with dark green foliage. Avoid tall, spindly plants. Smaller seedlings become established in the garden more quickly than larger ones. Also, smaller plants are often more productive. When selecting bedding plants, "large" is usually not better.
Bedding plants purchased from greenhouses or garden centers should not be planted directly into the garden. The intense sun and strong winds may damage or kill the tender seedlings. Bedding plants should be "hardened" (acclimated to outdoor growing conditions) before transplanting them into the garden.
Initially place the plants in a shady, protected site. Then gradually expose the plants to longer periods of direct sun. Closely watch the plants during this period. If possible, check on them at least once or twice a day. Thoroughly water the seedlings when the soil surface becomes dry to the touch. Move the plants indoors if strong winds, a severe storm, or an overnight frost threatens them. After 7 to 10 days of hardening, the bedding plants should be ready for planting.
Most annual flowers should be planted outdoors when the danger of frost is past. A few frost tolerant annuals, such as pansy, sweet alyssum, and snapdragon, can be planted 2 to 3 weeks earlier. Cabbage, broccoli, and cauliflower seedlings can be planted outdoors in early April in southern Iowa; gardeners in northern counties should wait until mid- to late April. Tomatoes, peppers, cucumbers, melons, and other warm season vegetables should be planted after the average last frost date in your area.
If possible, set the plants into the garden in the evening or on a cloudy day. Planting at these times lessens transplant shock and allows the plants to recover somewhat before being exposed to direct sun. Many annuals, such as petunia, snapdragon, salvia, and periwinkle, should be pinched back to encourage branching. Others, such as impatiens, are self-branching and don't require pinching. It's also advisable to remove flowers on blooming annuals. Blossom removal aids plant establishment. Vegetable transplants should not be pinched.
When watering newly planted transplants, apply a starter fertilizer solution to each plant. A starter fertilizer solution can be prepared by mixing 2 tablespoons of an all-purpose garden fertilizer, such as 5-10-5, in 1 gallon of water. When the fertilizer has completely dissolved, give each plant approximately 1 cup of the starter fertilizer solution.