More than 5,000 species of wildflowers along with native grasses flourish along our state's roadsides, thanks to nature and attention from TxDOT.
TxDOT's wildflower program not only helps our highways look good but also reduces the cost of maintenance and labor by encouraging the growth of native species that need less mowing and care.
As with grasses, Wildflower Program initiatives strive to establish roadsides that blend into their surroundings. The grasses and wildflowers also help to conserve water, control erosion and provide a habitat for wildlife in all the natural regions of Texas.
Maintenance techniques used to encourage wildflower growth include safety, or strip mowing which allows the wildflowers to bloom and native grasses to emerge.
TxDOT buys and sows about 30,000 pounds of wildflower seed each year. The peak wildflower blooming season draws tourists from all across the nation to see the color unfold each spring.
TxDOT is pleased with the attention wildflowers attract; however, we discourage picture-taking that damages the flowers. If too many wildflowers are trampled, they will die and not go to seed. Since many of these flowers are annuals, this means they have to go to seed to come back the next year. Naturally, we discourage picking the flowers for the same reason.
The wildflower program is part of good stewardship. Today, TxDOT not only plants and enhances wildflower areas, but more importantly protects and maintains the investment made in years past.
Bluebonnets grow best in soils that are alkaline, moderate in fertility, and most important of all, well drained. Full sun is also required for best growth. Seed may be planted September 1 through December 15; however, for best results, plant seeds no later than mid-November.
This allows seed time to germinate and grow throughout the winter months, during which time a heavy root system and a sturdy plant is developed to produce an abundance of spring flowers.
Bluebonnets produce large, hard-coated seeds that may cause them to have a low germination rate the first year or two. As the hard seed coats wear down by rain, abrasion and decay, the seedlings begin to sprout.
Soil preparation is not necessary; the seed can be broadcast over undisturbed soil. However, seed to soil contact is essential. When sowing seed in turf areas, make sure to scalp the grass as low as possible with a mower and rake up any thatch which may prevent the seed from contacting the soil.
Small areas can be sown by hand or with a mechanical hand device. Large areas require a seed drill or other mechanical means that can be calibrated for the seeding rate. For small areas, or places where you want a good display more quickly, seed companies recommend using 8 to 10 seeds per square foot. At that rate an ounce will cover approximately 135 square feet, and 1/2 a pound covers 1,000 square feet. An acre will require 20-30 pounds of seeds.
After seeding, it is best to cover the seed with soil no more than one-quarter inch deep. This protects the seed from being eaten by birds or "baked" by the sun. Water thoroughly but gently. Follow the first watering with additional light waterings every three days for about three weeks if rain is not present.
Fertilizing is not recommended as it will produce more leaves but not more blooms. Some seed will begin to sprout in 4-10 days. The germination process can continue over 18 months or more.
Be aware that one of the reasons bluebonnets fail to bloom is the lack of an essential bacterium in the soil. These bacterium known as rhizobium form nodules on the roots of the bluebonnet plant and are able to fix atmospheric nitrogen (this is the conversion of atmospheric nitrogen to a form usable by plants). This nitrogen fixation is needed for the bluebonnets to bloom.
Do not soak bluebonnet seed or prick it with pins or in any way disturb the seed coat. Although these methods can speed up germination, they can also damage the seed so that it is really better to let nature take its course.
In general, the first flowers open about March 15 in the southern part of the state, and in the more northern part of the state, first flowers may not show before May 1. The length of the flowering period is about a month. Allow two weeks after the full bloom period has passed for the seeds to mature.
As a rule of thumb, when the dead brown foliage offsets the floral color display, the area can be mowed. If it is a large area, it should be mowed to a height of 4-6 inches. Annual mowing aids in seed dispersal and reduces competition of unwanted weeds and grasses.
If you wish to store the seed, the pods should be harvested before they explode and scatter the seed. The seed should be thoroughly air dried on newspaper. Seeds which are not completely dry prior to storage will contain excessive moisture which will cause mold to grow and damage the seed.
After the seeds are completely dry, store in a water-resistant container. Add a packet of desiccant to the seed such as silica gel (which can be found in craft stores). This gel will remove any moisture that remains in the storage container after it is sealed. Seed stored under these conditions will remain viable for many years. Seed may be sown at harvest or stored for future planting in the produce section of the refrigerator until the fall.
Most Important Factors
In brief, it may be said that the most important factors in establishing bluebonnets are: (1) plant prior to December 15 (2) plant seed in soil well adapted for bluebonnets (3) make sure there is good seed to soil contact when planting.
These guidelines are very general and broad in scope. Some species of wildflowers may require additional research prior to planting. You may find our listing of wildflower planting dates and interactive regional seed list helpful.
Some wildflower seed suppliers can provide seed mixtures consisting of a number of different species. You have the option of such a mixture or obtaining the species of your choice and making a mixture or planting your selections individually.
After your selection is determined, a planting rate based on Pure Live Seed (PLS) and the number of seeds per square foot can be calculated. PLS is simply the percent of purity multiplied by the percent of germination which should be available from the supplier and as required by the Texas Department of Agriculture under the seed law.
These rates should be more accurately determined by the mature size of the plants and the effect you desire. The Soil Conservation Service recommends planting twenty seeds per square foot. For highway plantings, seeding is recommended in pounds per acre with the rate dependent on the type of seed used.
Soil preparation is not necessary since most wildflower seeds can be broadcast over undisturbed soil, although some delay in germination may result. However, seed to soil contact is essential. When sowing wildflower seed in turf areas make sure to scalp the grass as low as possible with a mower. Next, sow the seed.
After sowing, drag the sowed area with a weighted section of chain link fence or other rough flat object to better obtain soil-seed contact. Water the area thoroughly but gently. Follow the first watering with additional short waterings every three days for about three weeks. Some seeds will germinate 10-20 days after planting, others will germinate in early spring.
A method of application should be determined by the size of the area. Small areas can be sown by hand or a mechanical hand device. Large areas require a seed drill or other mechanical means that can be calibrated for the seeding rate.
Understanding Plant Characteristics
Another key factor to successful planting is to understand the characteristics under which each species thrives. By and large, most Texas wildflowers should be planted in late summer or early fall, especially bluebonnets.
Location is also important. Plant sun-loving plants in areas that receive adequate sun. Shade-loving plants, which will survive in full sunlight under special conditions, will thrive best in shady areas.
Most wildflowers have a wide tolerance of soil and pH (acid/alkaline) conditions. Bluebonnets (Lupinus texensis) prefer a well drained, calcareous, alkaline soil such as that of Central Texas and the Hill Country.
All wildflower seeds need moisture for germination and growth, but it is important to provide proper drainage, which will vary with the species.
A low nitrogen fertilizer can be used at the time of planting if the soil lacks nutrients. However, fertilizing after plants are established will result in larger amounts of foliage at the expense of blooms.