Drought, heat, and fatigue drain a mortal’s initiative this time of year in Austin, Texas. Our urban heat island effects make the problem worse. Gratuitous pavement, buildings, and turf fragment the vegetative cover and arboreal canopy. E.O. Wilson observed the tropical rain forest drying out as humans cut swaths through it. Crop fields, pastures, and roads open up the forest canopy and allow drying wind and hot tropical sunlight to desiccate the plants that would otherwise enjoy the humid shelter of trees and vines that maintained their required levels of moisture.
We face a rather different climatic and botanical situation here in USDA zone 8 – or what passes for it these days, but the fragmentation effect holds true here anyway. Last year, the spring of 2007 lingered so long that it pre-empted half of summer. Unusually wet weather continued until late July. I hardly needed to water anything in the garden until mid-August. This year seems destined to become the drought of 2008. The drought of 2006 seemed worse, preceded by a dry 2005, it cooked the trees by the end of summer. Central Texas found itself on the dry side of hurricanes Katrina and Rita that hit Louisiana in 2005. I lose track of “La Niña” and “El Niño” and their effects on our rainfall. I only know that Central Texas precipitation varies dramatically from one year to the next. At this time of the season this year, the weather reporters seem awed by the daily highs at or near 100° Fahrenheit since late May. We didn’t get temperatures like this until August two years ago.
Not all of our native plants hold up to this scorching heat in my garden. My house, situated on a roughly east-facing slope of limestone-caliche subsoil, overlaid with a thin layer of poor-ish topsoil – nowhere near moist alluvial soils – does not support all of the locally-native flora. Much of our more popular native species inhabit river bottoms. A pointed reminder of this annoying fact occurred to me during Kevin Anderson’s recent lecture on “Texas Riparian Ecology 101: the Science, the Issues and Austin’s Waterways” (Center for Environmental Research, Austin Water Utility, University of Texas, Texas A&M, and Hornsby Bend Biosolids Management Plant), June 16, 2008. So much for xeriscaping!
The Ladybird Johnson Wildflower Center tries to teach us about prairie plants that can tolerate our alkaline soils and intemperate climate but I don’t always get the message. Weather like the present hot spell reminds me and tests the appropriateness of my species choices on my particular site. So now, I celebrate the joys of plants that endure the heat and drought. Some even flourish in our harsh summer weather.
The family Bignoniaceae provides several reliable species. “Desert willow” (Chilopsis linearis) blooms relentlessly in the heat with lovely bells of pink, purple, and white. I propagated my trees both from rooted cuttings and seed equally well. They have grown to about 12 feet tall and about as wide in 6 years. The hummingbirds and bees love Chilopsis (not a real “willow” at all).
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We face a rather different climatic and botanical situation here in USDA zone 8 – or what passes for it these days, but the fragmentation effect holds true here anyway. Last year, the spring of 2007 lingered so long that it pre-empted half of summer. Unusually wet weather continued until late July. I hardly needed to water anything in the garden until mid-August. This year seems destined to become the drought of 2008. The drought of 2006 seemed worse, preceded by a dry 2005, it cooked the trees by the end of summer. Central Texas found itself on the dry side of hurricanes Katrina and Rita that hit Louisiana in 2005. I lose track of “La Niña” and “El Niño” and their effects on our rainfall. I only know that Central Texas precipitation varies dramatically from one year to the next. At this time of the season this year, the weather reporters seem awed by the daily highs at or near 100° Fahrenheit since late May. We didn’t get temperatures like this until August two years ago.
Not all of our native plants hold up to this scorching heat in my garden. My house, situated on a roughly east-facing slope of limestone-caliche subsoil, overlaid with a thin layer of poor-ish topsoil – nowhere near moist alluvial soils – does not support all of the locally-native flora. Much of our more popular native species inhabit river bottoms. A pointed reminder of this annoying fact occurred to me during Kevin Anderson’s recent lecture on “Texas Riparian Ecology 101: the Science, the Issues and Austin’s Waterways” (Center for Environmental Research, Austin Water Utility, University of Texas, Texas A&M, and Hornsby Bend Biosolids Management Plant), June 16, 2008. So much for xeriscaping!
The Ladybird Johnson Wildflower Center tries to teach us about prairie plants that can tolerate our alkaline soils and intemperate climate but I don’t always get the message. Weather like the present hot spell reminds me and tests the appropriateness of my species choices on my particular site. So now, I celebrate the joys of plants that endure the heat and drought. Some even flourish in our harsh summer weather.
The family Bignoniaceae provides several reliable species. “Desert willow” (Chilopsis linearis) blooms relentlessly in the heat with lovely bells of pink, purple, and white. I propagated my trees both from rooted cuttings and seed equally well. They have grown to about 12 feet tall and about as wide in 6 years. The hummingbirds and bees love Chilopsis (not a real “willow” at all).
Esperanza (Tecoma stans), also called, “Arizona yellow bells,” freezes to the ground with the slightest frost but returns reliably from hardy roots every year. I grew mine from seed collected downtown outside The Pit Barbeque, where now stands the Austin Convention Center Hilton Hotel. The mother tree, probably protected by one of our famous micro-climates, sprawled over 10 feet tall and 20 feet wide, as I recall. My specimen, lacking a similar micro-climate, shows no signs of such vigor. It does bloom reliably from June to October or so.
Pink trumpet vine (Podranea ricasoliana) produces an abundance of stunningly beautiful flowers on a profusion of woody vines that return from hardy roots every spring. Without pruning, it can easily produce vine-like canes 15-20 feet long in one growing season. It looks particularly beautiful when trained up an otherwise blasted fruit tree, from which it can cascade down like a giant bridal veil. My mother loves the flowers, but the vine has become a dreadful thug in warm, wet, nearly frost-free Beaumont. Our freezes keep it in bounds here in Austin. I have propagated this plant repeatedly from medium-wood cuttings and layering. Podranea rarely produces seed here in Austin before a frost destroys the fruit.
I don’t grow crossvine (Bignonia capreolata), but have seen it gracing large trellises and fences around Austin. Instead, I grow its more unruly cousin, orange trumpet vine (Campsis radicans). Don’t ask why, I seem to cultivate an affinity for aggressive plants. Seeing this plant grow out of a crack in alleyway pavement and climbing brick walls and telephone poles despite neglect and outright hostility from property owners, I decided that this would make an excellent self-cleaning hummingbird feeder. It does that.
In an earlier post, I mentioned violet Argentine trumpet vine, Clytostoma callistigioides. It grows very aggressively in Beaumont (with about twice Austin’s average annual rainfall). Unfortunately, it takes a very long time to get established in my garden. I had hoped it would climb the long-suffering weeping willow in front of my house (nowhere near pond or stream). Both still survive, I still wait for Clytostoma to climb.
Catalpa tree (Catalpa bignonioides) also grows well here in Austin, but not in my garden. I found an especially healthy specimen in Waterloo Park in downtown Austin recently. Some people dislike its large, white, fleshy flowers dropping carelessly all around – especially if towering over one’s driveway. Its large heart-shaped leaves might furthermore present a maintenance issue in a small person’s fastidious garden (or vice versa), but in the park, next to the creek, it looks quite lovely.
I don’t grow crossvine (Bignonia capreolata), but have seen it gracing large trellises and fences around Austin. Instead, I grow its more unruly cousin, orange trumpet vine (Campsis radicans). Don’t ask why, I seem to cultivate an affinity for aggressive plants. Seeing this plant grow out of a crack in alleyway pavement and climbing brick walls and telephone poles despite neglect and outright hostility from property owners, I decided that this would make an excellent self-cleaning hummingbird feeder. It does that.
In an earlier post, I mentioned violet Argentine trumpet vine, Clytostoma callistigioides. It grows very aggressively in Beaumont (with about twice Austin’s average annual rainfall). Unfortunately, it takes a very long time to get established in my garden. I had hoped it would climb the long-suffering weeping willow in front of my house (nowhere near pond or stream). Both still survive, I still wait for Clytostoma to climb.
Catalpa tree (Catalpa bignonioides) also grows well here in Austin, but not in my garden. I found an especially healthy specimen in Waterloo Park in downtown Austin recently. Some people dislike its large, white, fleshy flowers dropping carelessly all around – especially if towering over one’s driveway. Its large heart-shaped leaves might furthermore present a maintenance issue in a small person’s fastidious garden (or vice versa), but in the park, next to the creek, it looks quite lovely.
The bignonia family absolutely earns its keep in Central Texas landscapes – even during our brutish summers.
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