GardenSmart :: EPISODES :: 2005 show38
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Show #38

This week we visit Tohono Chul Park In Tucson, Arizona and will introduce some terrific desert plants, many of which can be used in your own homes, even gardens. Often when thinking about desert we think hot, dry, barren. But that is not always the case. You'll be surprised at the vivid colors.

Barbara McDonald with the Tucson Convention and Visitors Bureau introduces us to Tucson. Tucson comes from the Native American, Tohono Otom tribe, and it means "spring at the foot of black mountain. It was originally pronounced in a way that sounded like "chucksan," over time it became Tucson. Many think a desert will be barren looking. However, there are many wonderful plants, especially during spring blooming time. There is color everywhere. As well, the mountains provide a wonderful backdrop against the desert. Tucson is indeed a unique, beautiful place.

One of the best places to see the native environment in Tucson is Tohono Chul Park. Russ Buhrow is the Curator of Plants at this wonderful park and our guide today. Russ says one must realize these plants are happy in this environment. When first coming to this area go into the desert, go into the mountains, go after it's rained and it is beautiful. You'll see some amazing, magical plants.

Tohono Chul is a plant persons place. It is known as a cutting edge place for new plant introductions because they're bringing many native plants into the landscape trade that aren't available anywhere else.

Desert plants deal with extreme conditions. The sun, for example is intense. The average person can get a sunburn in as little as 10-15 minutes. It has very high solar intensity. Plants can't hide from the sun, they can't duck into the shade. The lack of humidity or lack of moisture also causes the sun to be more intense and adds stress to the plants because they lose water more quickly. An example that brings the point home is-if you pull a weed in an area with a humid environment and throw it on the ground that weed will wilt within a few minutes and be dry in several days, if you pull up a weed here, it will be dry in a few seconds and crispy in an hour. Occasionally this area has high winds, but normally they are less than 10 miles an hour. Water is a key issue. Average rainfall is 12 inches per year and that varies from 6 inches to as much as 20 inches. If every month they received an inch of rain everything would be fine, but that's not the way it works. The last time they had a bunch of rain was 1983. Two months passed with no rain then 12 inches fell within two days. The plants need the ability to hold and to store water and use it over a longer period of time. Many of the plants can use water stored in the soil, others need to be very patient and wait for water. This area has two specific rainy periods, one happens in winter, from October through March and the second, with about twice as much water comes in the summer, usually late June to early September. Plants may have to go 3 or 4 months without water. This is not only inconsistent water but the temperature extremes are also harsh. The highest recorded Tucson temperature was 117 degrees, the minimum 13, although it may have been as low as 0. The plants become highly specialized in order to survive. The soil is also unique. Although variable, like other parts of the country, it ranges from gravel and rocks to clay. In this desert the soil rarely gets wet below 2-3 feet. The soluble nutrients in the soil are leached downward, the water stops going down, gets sucked back up by the plants and dry air, the leached solids are deposited and a sub soil develops. It is called Caliche and is a Spanish word that describes the calcium contained within. It is a rock. To break it one needs a jackhammer or something called a Caliche Bar, a pointed digging bar with a spade on the other end. One starts digging, when the Caliche is hit one can tell the quality of Caliche because when reasonably good Caliche is hit it's hard, like hard pan. When a really good gem grade Caliche is hit fire shoots from the end of the digging bar. If the Caliche is not too thick, one can break through it. Once done, since sand is underneath the Caliche, there is perfect drainage. If the Caliche is too thick or tough, raised beds may be the only answer.

Holding water is important for these plants. We look at the root of a Prickly Pear, it is waxy, completely sealed. The feeder roots are active and still pulling water, indicating there is still some water in the soil. When this root is completely dormant the feeder roots will die back, leaving the main waxy root. When the rains come the feeder roots will explode out. The morning after a rain, Russ has seen, within an inch of the roots, all the water extracted. Literally within 24 hours a plant can go from dormant to the main feeder root exploding with all the smaller roots developing and absorbing water. Within 2-3 days the Cactus will go from a sort of shriveled state to fully expanded, thick pad state. It can then hold on to water for months if needed.

If you live in a part of the country where it gets hot in the summer and that's just about everywhere, think about the temperature inside your hose. If leaving it on a hard surface like asphalt or concrete the temperature of the water inside the hose may reach over 100 degrees. So, turn on the water, let it run a little until the water on your hand doesn't feel hot. Otherwise it could burn your plants, especially if they're in a container or young and tender.

The diversity of plants at Tohono Chul is amazing. We look at several that don't fit the typical desert stereotype. Sacred Datura, made famous by Georgia O'keefe is found throughout the Southwest. It is drought tolerant, it does this by going to sleep. If it's really cold or really dry it dives into the ground. When it rains or the temperature warms it explodes out of the ground and can be several feet tall within a couple of days. The flower is beautiful, the length of the tube is amazing. The nectars are at the bottom, thus ideal for long tongued insects. The flowers are very white, they're night blooming which helps them conserve moisture and attracts night flying animals. It doesn't have spines but instead protects itself through chemistry. It is loaded with toxins and alkaloids. An animal takes a bite, gets sick, starts to hallucinate, gets disoriented and learns not to bother that plant again.

Bouvardia Glaberrima is a red-orange plant, native in Arizona in elevations of 3,500-6,000 feet. It does fine in the mountains but needs irrigation in the valley. Hummingbirds love this plant. Hummingbirds look for plants with red or bright colored flowers and long tubular flowers. Hummingbirds are not only looking for nectar but also looking for insects and spiders. With these plants the flowers are far enough away from the foliage so that the Hummingbirds can easily get to them.

In full sun or in hot weather use cool color plants. Verbena is a good choice, the light purple contrasts with the hot sun. This plant is Native Gooddings Verbena. It grows in the mountains and will grow in Tucson with a little extra water. It will last from 6 months to about 2 years. The term perennial means it's supposed to live more than a couple of years but some are very short lived while some live long periods of time. Verbena is a great choice if in well drained soil, keep moisture off the leaves and in the winter they hate wet feet. It's a great choice for this part of the world or any place where it gets hot and dry.

Desert Marigold has an intense yellow flower and silvery foliage. It is a native of low desert elevations and is a common roadside weed. Plants in this part of the world have a pubescent or fuzz all over the stem. It helps reflect the sun and offers shade. Overhead irrigation isn't a good choice, they don't do well with water on their leaves and they don't like humidity. This is a perfect environment for them.

Eupatorium Greggii has light purple, soft fluffy heads and serrated foliage. Butterflies like this plant, in particular an orange butterfly called "The Queen," a miniature relative of the Monarch. The male Queens come to the plant, get a chemical out that makes them irresistible to females. It's an aphrodisiac. A favorite variety of this plant is called "Boot Hill" and got its name because it was collected next to Boot Hill, near Tombstone Arizona, home to the fight at the OK Corral.

Fallugia Paradoxa or Apache Plume is a native plant that grows between 4,000-6,000 feet in the mountains. It has white flowers which are followed by clusters of fruit. The fruit also looks like flowers or a plume, even a paint brush. It looks like it has two flowers. They like a little bit of water but aren't heavy water users - low to moderate. They would grow in many parts of the country, have adapted to cold temperatures and should be good down to around zero. If grown in the Eastern U.S. add limestone, not lime, to the soil to make it more alkaline.

When placing plants like Cactus and Yucca, which are native to a lot of different parts of the country, be careful in terms of visual energy. The plants are striking, very upright, have a huge bloom, are reasonably coarse textured and command attention. Only place these plants where you want to draw the eye, where you want the eye to linger.

When selecting trees consider height and spread, the leaves and flowers but also consider the bark. The Foothill Palo Verde is a native tree found all over Tucson into the upper parts of the valley towards the mountains. It's bark is almost chartreuse. It has become a hot tree to dig up and take to Los Angeles. It grows to a large size, this one, the biggest known, is about two feet thick, 30 feet across and 25 feet tall. It provides filtered shade enabling quite a few plants to thrive underneath. They don't like wet feet, they're good down to the low 20's or teens. Be careful in pruning, they die back below the cuts, like an Olive. It's often better to prune them when little or let the branch die and break them off, providing more of a wild feel. They get very brittle when dry allowing them to be snapped easily. They look spectacular at night with uplighting.

Mesquite Prosopis Velutina is an important tree to the native people in this area. They collected pods, crushed them and made flour, then food. We know the Mesquite timber because it is frequently used in barbecuing, providing a wonderful flavor. These trees grow in different parts of the country. It has a lovely dark bark, is fairly small, will grow to 80 feet across, about 6 feet thick and 50 feet tall, depending on the moisture it receives. The root system is extensive. They'll have lateral roots that might go out to the side 3-4 times its' height. There are records of roots being found in mines up to 400 feet deep. The dark bark with lights behind it make a stunning contrast. Another idea is to put them against a flat stucco wall, when the light comes through it provides dramatic lighting on the wall.

Thank you Russ for taking time from your busy schedule to show us this magnificent garden. These plants represent the area but may adapt to other parts of the country, as well.

Link :: Tohono Chul Park and Westward Look Resort

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