For The Answer
Saturday, February 1, 2003
Submitted by Calvin Finch, Ph.D., Manager, Conservation Division, Water Resources & Conservation Department, SAWS, and HorticulturistBLUEBONNET AND LARKSPUR TRANSPLANTS
If you have visited your nursery lately you probably noticed bluebonnet and bunny larkspur transplants.
It is too late to plant bluebonnet seed and expect blooms this spring, but the transplants will perform well and may be the beginning of your reseeding wildflower planting. You have two choices with your bluebonnet transplants: 1) you can plant them as an annual in your flower garden or 2) you can plant them on a site where competition is minimal and they can reseed to produce plants again next fall for blooms the following spring.
Bluebonnet transplants are petite now but, beginning in early March, they will become large plants 18 inches tall and 2 feet in diameter if you plant them in a raised bed in full sun. Give them plenty of space (at least 1 ft apart), fertilize with one-half cup of slow-release lawn fertilizer, and water them at planting. Limiting the watering to a soaking at planting is important; nothing is more deadly to bluebonnets than over watering. Mulch is also undesirable because of the problem with damp soil—the roots rot quickly. When the plants are in a flower garden situation, it is also a good idea to watch for caterpillars. The small white larvae will strip them quickly. Apply a Bt product like Dipel, Thuricide, or Bio-worm Control to kill the pests if they appear.
Bluebonnet transplants can also be used to start your wildflower patch. In this case, you want to find a site in full sun where the sod and weeds do not prosper. To persist on a site the bluebonnet seed must reach the soil and not be shaded from the sun. A vacant lot with heavy soil that dries out each autumn is perfect.
Place your transplants spread over the site or, for more visual impact, concentrate them in drifts of five or more plants with 2 ft. between plants. Remember, to allow bluebonnets to reseed the blooms must be allowed to decline and form seed pods. The seedpods should show a straw color before the plants are mowed down. The main bloom period is in April.
Bluebonnets are not eaten by deer. Another deer-proof plant that reseeds itself is larkspur, also called delphiniums when they are in the double form. Larkspur reseed best when they are grown in prepared beds. Some plants will germinate in the dry soils described for bluebonnets, but for solid stands raised beds are best. Some delphiniums are tall top-heavy plants that can be blown over if the planting is a thin row or in a windy location. The simple petaled bunny larkspurs found in the nurseries now, however, seem to be sturdy enough to stand in the open. Bunny larkspurs are called “bunny” because you can see a bunny head in the flower if you have some imagination. They come in blue and pink pastel shades. The delphiniums are purple, blue, pink, and white. As the years pass the delphiniums revert to simpler flowers as they reseed.
The larkspur in my garden are about 4 inches tall now. I will thin them to 12 inches apart. Plant your transplants about 1 foot apart also. As with bluebonnets the pods must be allowed to mature their seed before the dry plants are removed. The good news is that, by the time the flowers begin to decline, a large amount of seed have been produced and dropped. Discard the spent plants in the compost pile or, better yet, place the harvested plants and the seed that remains on new sites so more beds will be created.
After the larkspurs are removed in April, you may plant zinnias or gomphrena in the bed. Both of those plants will also reseed during warm weather, and the larkspurs, zinnias, and gomphrena are favorite butterfly and hummingbird plants. Zinnias are also deer proof. Remember to allow your annuals to reseed; the bed must be free of mulch.