AMES, Iowa – As home gardeners prepare to buy annual flower and vegetable transplants from local garden centers and greenhouses, or move plants started indoors to gardens, consider these tips from Iowa State University horticulturists to help ensure a successful start to the gardening season. Select strong, healthy plants and harden them outdoors for a few days prior to planting. Proper planting is another key to success. To have more questions answered, contact Hortline at 515-294-3108 or hortline@iastate.edu.
What should I look for when purchasing annual flower and vegetable transplants?
Select short, stocky plants with dark green foliage. Avoid tall, spindly plants. Small to medium-size transplants become established in the garden more quickly than large ones. Short, stocky vegetable transplants are often more productive than large plants with flowers or fruits. When selecting annual flower and vegetable plants, large transplants are usually not the best choice.
Do annual flower and vegetable transplants need special care before planting?
Annual flower and vegetable plants started indoors (in the home) or purchased from greenhouses should not be planted directly into the garden. The intense sun and strong winds may damage or kill the tender transplants. 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 transplants 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. Transplants should be ready to plant after six or seven days of hardening.
What is the proper way to plant annuals and vegetables in the garden?
Carefully remove plants from plastic cell packs by gently squeezing the bottom on each compartment. Plants in plastic pots can be removed by tipping them on their sides and tapping the bottom of the pots.
If possible, plant annual flowers and vegetables in the garden in the evening or on a cloudy day. Planting at these times lessens transplant stress and allows the plants to recover somewhat before being exposed to the strong, mid-day sun. Place plants in the ground at the same depth or slightly deeper (no more than .5 inch deeper) than they were in their containers. (Tall, leggy tomato plants can be planted much deeper than previously grown, as roots will develop all along the buried stems.)
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. After planting, thoroughly water each plant. Continue to water the plants on a periodic basis for 10 to 14 days.
— Richard Jauron and Willy Klein, Iowa State University Extension and Outreach
For more news from Iowa, click here.