How to grow and care for blue bonnets

To successfully grow and care for bluebonnets, choose a sunny site with well-drained soil, plant scarified seed, and don't overwater plants after they're established.

How to Grow and Care for Bluebonnets

Bluebonnets, famous as the state flower of Texas, are a species of lupine that also grow in New Mexico, Florida, Louisiana and Oklahoma. Texas bluebonnets (Lupinus texensis), the most common species, reach about twelve inches tall and sport deep blue and white-tipped flowers above blue-green palmate leaves. Check your garden center for the latest color varieties, which to date include white, pink, purple, red, maroon and lavender. Bluebonnets bloom from around the middle of March to the middle of April, so plan your garden design accordingly.

Be picky when choosing the right site for your bluebonnets - they prefer well-drained, alkaline soil conditions in a sunny site. If your soil is too wet or compacted consider building raised beds to increase soil drainage and control soil chemistry. Bluebonnets do well in single plantings or you can interplant them among other garden plants in a mixed border. Remember that bluebonnets self-seed and will come up every year if the growing conditions are suitable.

Bluebonnets belong to the legume, or pea family, and their seeds develop in a pod that splits open to release the seeds when they are mature. Bluebonnet seeds have a thick coat that needs to be scarified, or artificially weathered, so that water can penetrate the seed coat and initiate germination. Purchase pre-scarified seeds (these are usually soaked in sulfuric acid), or, if you only have a few seeds to plant, try scarifying seeds yourself by scratching the seed coat with a knife, sandpaper or a file, or by mimicking winter freeze and thaw cycles by freezing seeds overnight and then drenching them in boiling water (to break open the seed coats). After scarifying the seeds, soak them in water for a day to jump-start the germination process. One word of caution: bluebonnet seeds contain poisonous alkaloids, so keep them away from children and livestock.



Another factor that may influence successful bluebonnet growth is the presence of a soil bacterium called Rhizobium, which fixes nitrogen in the soil and helps feed the plant through little bumps on the roots, called nodules. Insufficient amounts of Rhizobium may result in seedlings that fail to grow to maturity. Check the roots of slow-growing or sickly plants for nodules - if you don't see any, consider buying seed that is pre-inoculated with Rhizobium, or buy Rhizobium powder to spread on the soil prior to planting seeds. Consult your garden center experts for information about sources and application instructions. Another option is to apply a slow release fertilizer in spring to give seedlings a boost.

Bluebonnets are a winter annual, which means that seeds planted in fall germinate and spend the winter as seedlings before maturing, flowering, setting seed and dying the following year. Plant bluebonnet seed from September through November (the warm weather will encourage germination). To plant bluebonnet seeds, select a sunny, well-drained area and till or rake the soil to roughen its surface. Because these seeds require water to germinate, they must be nestled tightly into the soil to ensure they have enough exposure to moisture. After spreading the seed (about 5-10 seeds per square foot), cover them very lightly with soil (not more than an eight of an inch) and tamp the seeds down to make sure the seed has good contact with the soil. Bluebonnet seedlings depend on cool winter rainfall to develop strong root systems, so if rainfall is low, water the seedlings lightly. Be careful not to over water, because this promotes fungal infections that will kill the plants - remember that bluebonnets prefer well-drained soils! Bluebonnets will self-sow, dropping seed every fall, and the subsequent winter weather will scarify some of the seed and produce seedlings for years afterwards.

After the bluebonnets are established and flowering, pinch off the old flower stalks at the base to induce further flowering. When the plants have finished blooming, they will produce pods filled with seeds and the foliage will start to turn yellow and spindly. Some gardeners prefer to pull out the plants at this point; others want them to self-seed for next year and prefer to wait until the seeds have matured and dropped from the pods (about six to eight weeks after blooming). Plant other flowering annuals, such as pansies, in between the yellowing bluebonnets to hide them while waiting for the seed pods to drop. To collect seeds to plant elsewhere, wait until the seed pods begin to dry (they will turn brown and wrinkled), and then tie a paper bag over the pods to catch ripe seed as it falls from the pod. Store the seed in a cool dry place until ready to plant in the fall.

Another option for growing bluebonnets is to plant transplants directly into your garden in spring. Transplants are usually available from garden centers in small peat pots that may be planted directly into the soil. Make sure the leaf bases, where they attach to the root crown, are above the soil line if the transplants are removed from the pot before planting. Planting transplants may also be a good option if the soils nutrients are low, because the plants bring their own soil nutrients and microbes (including Rhizobium) with them. Place transplants about a foot apart and water as necessary until established.

Tips to remember: choose well-drained soil in a sunny spot, plant scarified seed in fall or transplants in spring, don't overwater, and you'll have a patch of Texas spring to call your own every year.

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