the show

Natives not Invasives

air date: April 12, 2014

See how and why to swap invasive plants for native holistic ecology with tips from Jessica Wilson.
On tour, Laura and Andy Stewart reclaimed their in-town lot smothered with invasives. Daphne answers: Does it really take a century plant 100 years to bloom? Her plant of the week is Agave and how to select the one for you. William Glenn compares composts.


Episode Segments

On Tour

Urban wildlife habitat restoration | Laura & Andy Stewart |Central Texas Gardener

On a hillside urban lot not far from a busy highway, Laura and Andy Stewart revived native species smothered under a jungle of exotic invasives. Working with David Mahler from Environmental Survey Consulting, they restored a wildlife habitat of daily discovery for their family within biking distance of downtown.  House design by Miró Rivera Architects.


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Question of the Week

Does it really take 100 years for “century plants” to bloom?

Our question comes from Central Texas Gardener’s Facebook page.

First, century plant is Agave americana. And no, it doesn’t take 100 years to bloom!  Okay, a little more detail:  Agave Americana DOES take a very long time to bloom, but it’s far less than a century.   It’s more like a decade or two, and usually somewhere between 10 and 30 years.

Unlike most plants, which you probably want to bloom immediately, and year after year, this is one that you want to wait as long as possible to bloom, since once it does, the main plant will die.  This is the same thing with all agaves, since they are monocarpic, meaning that they die after blooming.

And while there are few things more beautiful than a large century plant in bloom, there are few things uglier than a dead one.  As soon as century plants and other agave species start blooming, I get inundated with calls from frantic people who know enough about agaves to panic at the first sight of its delicate little floral bud.  Everyone wants to know if they can stop this process and keep the parent plant alive.

Unfortunately, the answer is no.  This is one area of nature that man has yet to figure out how to tame, so you should just enjoy that beautiful bloom stalk.  In the case of Agave americana, it will be striking, getting up to 30 feet tall.

BUT, these bloom stalks can actually be hazardous, since as they grow and mature, the mother plant is slowly dying, giving that lanky bloom stalk less stability with each passing day.  Eventually, if you don’t remove the plant first, the top-heavy bloom stalk will topple over and rip the dead agave out of the ground. That could make for quite a mess, and even some damage to surrounding structures.

Some people even stake the bloom stalk to balance its weight.  If you like, you can collect the seeds from your agave and replant.

But even before flowering, most likely you’ll have baby plants (offsets) around the mother plant.  These plantlets are basically little clones, and can be dug up and planted in other areas of your landscape, or placed in containers, so that you’ll have a replacement for that spot when the original plant dies.


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Plant of the Week



There so many great species to choose, especially as more gardeners look for low-water plants in our continued drought. Before choosing yours, consider their mature size and stick-ability! You don't want a huge agave at maturity to overwhelm your space or stab people walking on a pathway. Some, like the squid agave (A. bracteosa) have softer leaves and remain smaller. There are many colors, forms and sizes, so choose the ones that complement your garden. Like the very large century plant (Agave americana) most agaves take quite a while to bloom. Mostly there are monocarpic, meaning that they die after blooming. There are some exceptions like the squid agave. But even before flowering, most likely you'll have baby plants (offsets) around the mother plant. These plantlets are basically little clones, and can be dug up and planted in other areas, or placed in containers, so that you'll have a replacement for that spot when the original plant dies. All agaves need well-drained soil, so if you have heavy clay and can't change it, you should choose other low-water plants. If you can amend the planting area, replace the clay with very sandy soil, mixed with coarser decomposed granite or expanded shale, and consider building bermed areas, so that drainage is increased even more with the elevation. Or, plant them in well-drained containers as accents. Also, be sure to know their origin. Some agaves are native to Central Texas and can take our occasional cold winters just fine. Agaves that are native to the Chihuahuan desert would also be good for our area, since their native region has cold winters. But agaves native to the Sonoran desert of southern Arizona are not accustomed to the cold, and should be protected in winter. So, do take a look at the plant tag at its cold hardiness, and whether it's one for the ground or a pot to protect in winter.