Zanthan Gardens
Weblog of a Central Austin Garden

I had a question recently on gathering bluebonnet seeds: how do you know they are ripe? It’s pretty easy to tell. When the shells turn brown, tap the shell. If you hear the seeds rattling inside, they are ripe. However, wait too long and the shell will explode when you tap it, throwing seeds everywhere. Lying in a field of bluebonnets on a hot May day, listening to seedpods pop is a classic Texas summer pastime.

Ripe bluebonnet seeds open with a pop and a twist to disperse their seeds.

If you want to start bluebonnets in a new spot, you can cut whole ripe stalks (like the one above) and let them seed themselves in their new home. This is the easy-going natural method of seeding, great for wild areas. It might take several years to get a good stand going. That’s because bluebonnet seeds have coats of different thicknesses. Some wear thin and sprout the first year. Others take several years. This is a survival tactic to ensure that all the seeds don’t sprout at once, only to be lost to bad weather.

Bluebonnet seeds ripe versus unripe. The green ones are NOT ripe and will rot if you try to plant them.

People tend to want all their seeds to sprout together, so commercial seed providers sometimes wear down the coat with an acid bath. People who gather their own seeds gently sand the outer coat down a little, just enough for water to soak in. I don’t do any of these things. Don’t need to. After a couple of years of growing bluebonnets, I’ve always had too many sprouts each fall. Individual plants (which contain multiple flowers) grow like small bushes to about 18 inches tall and two feet in diameter. In a small garden, you don’t need very many. I deadhead them to encourage more flowers and only let the best go to seed.

When you’re ready to clear out the bluebonnet plants, don’t pull them out by the roots. Cut them off at ground level. The roots are covered with nodules containing nitrogen-fixing bacteria. Not only are bluebonnets beautiful, they enrich our soil.

The same seed-saving advice holds true for larkspur (pictured above), nigella, and poppies. Wait until the pods are brown and the seeds are hard enough to rattle when you shake the pods.

If you have meadow plants in your garden, letting them go to seed means letting the garden look a bit messy for a few weeks. You’ll quickly understand why the word “seedy” means shabby and squalid. The payoff is a hundreds of free self-sown plants next year.

I worry that 2008 might not be a very good for Texas’s beloved state flower, the bluebonnet. Under ideal conditions, bluebonnets sprout in late September or early October after fall rains break summer’s hold. By Christmas, each plant has formed a flat rosette about the size of a salad plate. The root system gets firmly established as the rosette grows to dinnner plate size. By late February, the bluebonnet sends up multiple stalks forming a compact little bush with a flower at the end of each stalk. If you pick these first flowers, the bluebonnet will stay bushy and more flowers will form on side shoots.

However 2007 was an odd year weather-wise. Austin enjoyed a cool, wet summer and endured a hot, dry fall. In my yard quite a few bluebonnets sprouted from fresh seed in June. Although this happens every year, these early summer seedlings rarely survive the heat and droughts typical of August in Austin. In 2007, seventeen plants ended up successfully oversummering and are already forming little bushes. On December 15th one of these flowered.

2007-12-22. The bluebonnets which grew over the summer are now forming small bushes ahead of schedule.

Unfortunately very few bluebonnets began sprouting in the fall of 2007. Only in the last couple of weeks of the year did I begin seeing new seedlings. Of course, they are quite small for this time of year, only a a few true leaves rather than a large rosette. And the weather remains very, very dry which means that they are not getting off to a good start.

2007-12-22. This bluebonnet just sprouted; it is a couple of months behind.

2007-12-22. This time of year, the bluebonnets plants are usually form rosettes about 6 inches across.

While the gardener may fret, the bluebonnets are employing their long-term strategy for survival. Their seeds have a tough coat which makes them difficult to sprout when dry. The coats are of various thicknesses so that only some of the seeds sprout in the same conditions and other remain in reserve until their coats are worn down. Even though the plants are fewer and smaller, once conditions are right, they will still manage to send up a flower or two. The seeds that didn’t sprout this year are waiting to sprout next year.

Now I’m waiting to see what the other oversummering bluebonnets will do. Will they also flower early? Will they be more subject to freeze damage in January and February? Or will the plants just sprouting now catch up to the plants which have been growing last June so that they all bloom at once?

Several people have asked me how to propagate bluebonnets…how to tell if the seeds are ready. It’s easy. Don’t cut back the bluebonnets or mow until the seed cases are brown and you can hear the seeds ratttling inside. If you tap the seed case and it pops open, you know they’re ready.

To release their seeds, bluebonnets pop open with a little twist.

You can let the seeds reseed on their own (a bunch will anyway, as long as you don’t mow). With this method, some will be lost to birds, fire ants, and hot weather. Or you can collect the seeds, store them in a cool dry place, and sow them where you want them in August before the fall rains. If we have a rainy early summer, some bluebonnets will sprout now but, unless you baby them through the long, hot summer, they probably won’t survive until fall.

Bluebonnets naturally sprout in the fall, grow all winter, and flower the following spring.

You’ll find all sorts of advice for nicking the hard seed coats or rubbing them with sandpaper. This might be necessary with old dry seeds that you buy. I never do it because my own seed is fresh. Sometimes I soak them overnight or until they plump up. I did this the first couple of years to get started but now I have more sprouts than I can deal with an so I don’t need to go to any extra trouble. I let them sprout and transplant them where I want them.

Bluebonnets have hard coats so that they don’t sprout all at once if it rains. In Texas, it might rain and some sprout, and then die off in a long dry spell. But since they don’t all sprout at the same time, some are kept in reserve until more favorable conditions present themselves.