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Herbaceous perennials are becoming more and more popular. New varieties, greater availability of plants from local nurseries and the desire to include something a little different in the garden all play a part in the resurgence of perennial gardens. Include some for your own garden and make it water thrifty at the same time. Water conserving perennial gardening involves more than just choosing certain plants. Those that are successful for the long term include proper attention to soil preparation, mulches and weed control.
Perennial gardens are real treasures if they are done correctly, but they are not without peril. The greatest risk comes from weeds. Weeds use as much or more water than the plants themselves. Garden plants can never thrive if the weeds are stealing the water. The worst offenders are those ‘outlaws with their pictures on the post office wall' so to speak. Perennial weeds in perennial flowers are certain disasters. Once planted, perennial plants are there to stay and taking out noxious weeds is next to impossible.
These noxious weeds include field bindweed, whitetop, quackgrass, bermudagrass and several others. All have deep spreading taproots that are likely to go deeper and spread more aggressively than your chosen garden perennials. If you have these weeds in the area you want to plant, get them under control before you plant. This process will usually take several seasons.
Never skimp on soil preparation. Perennial enthusiasts recommend double digging the beds. Double digging is a matter of digging the beds deeply and turning the soil over while adding substantial amounts of organic matter. Soil preparation is essential. Prepare soil before putting perennials in the ground. Unlike annuals beds, you cannot till and add organic matter every year. Mulches are also important assets in water thrifty gardens. Organic mulches improve soil as they decompose, they help control water-robbing weeds and they cool the soil and reduce evaporation. Be generous with mulch as you grow your perennials and the flowers will reward you well.
After thoughtful preparations, spend some time selecting the plants. The challenge with perennial flowers is to select those that need similar conditions. Many gardeners start out to design waterwise planting. The plant the plants and are not willing to let them become established well. They then start to mix in some thirsty annuals or perennials and then water for those thirsty plants. That, in effect, negates any of the benefits of designing the garden for saving water.
Be prepared to accept the fact that many water thrifty plants normally bloom in the spring and may not be showy for long periods. It is also important to zone the sprinkler system. You will never achieve significant water savings if you try to water all of the plants the same way you water the turf.
These perennials are some of my favorites that grow well in the area. They are grouped according to their low water needs. Local nurseries are expanding their selection and some are available from specialty growers in the area. The list could include many others if you so desire.
The first group of plants will grow with no supplemental irrigation once they are established. They will flower better if they are watered once or twice per month. As a group, the penstemons are some of my favorite plants. They have excellent drought tolerance and they come in many beautiful colors. Heights range from small dwarf varieties to flowering beauties that will grow as tall as you are.
The native Wasatch penstemon has a brilliant blue flower that you can easily pick out when it is growing on dry hillsides. It will also show up well in your garden. It blooms in the summer and grows to about 24 inches tall. Rocky Mountain penstemon looks similar but has a purple flower. All penstemons favor full sun.
Another blue flower is Blue flax. The airy plants spread easily by seed and can be invasive. It also is a summer bloomer and grows up to 18 tall.
Porters Sulphur flower also takes dry conditions. It is a low spreading plant that never gets more than 6 inches high. They light yellow flower come in summer and the plants have interesting leaves even when they are not in bloom.
The next group of plants tolerate a single irrigation monthly if needed but flower better if watered twice per month from June through August.
In this group includes the yarrows. The most common is that with the white flowers. This variety can become a troublesome weed but colored selections are more manageable. Fernleaf yarrow produces large clusters of dark golden flowers. It will grow to 36 inches and makes an excellent cut or dried flower. It is competitive, but can be controlled with a little effort.
Wooly yarrow grows to 8 inches tall with a fuzzy creeping groundcover look. The yellow flowers are a striking contrast to gray green foliage. Greek yarrow has a similar appearance with white flowers.
Coneflowers are prominent for their medicinal qualities. The plants are easy to grow, very attractive, and usually suffer no pest problems. The most common color is purple but selected cultivars come in yellow, light green and white.
Varieties to check for locally include 'Alba' ‘White flowers' 'Bravado' ‘Larger rosy-red flowers with maroon centers' 'Bright Star' ‘Large, rosy-red blooms with maroon centers' 'Crimson Star' ‘Flat, crimson red flowers' and 'Kim's Knee High' ‘A dwarf only 15 inches tall, pink flowers'. Other selections include 'Magnus' ‘Rose colored flowers on 3 foot tall plants' 'Ovation' ‘Single, rosy-pink flowers' and 'White Swan' ‘White flowers on plants 3 feet tall'. Add perennial flax for a beautiful blue spring flower. It grows to 18 inches and is carefree providing you do not try to grow the plants on heavy clay or wet soils.
As a group, the sedums and sempervirens are excellent drought tolerant plants. Dozens of types are available including the familiar hen and chicks, the Dragons blood groundcover and the taller ‘Autumn Joy' sedum that grows to 15 inches. All tolerate heat and drought very well.
A common feature of many gray plants is that they are drought tolerant. Artemisia plants including the native sagebrush comes in many sizes and textures but they all are drought tolerant. If fact, the plants quickly develop root rot and die if they are grown in wet soils. ‘Silver Mound', ‘Powis Castle' and ‘Silver Brocade' are among the most common varieties.
Many new varieties of rudbeckia or Black-eyed Susan are appearing at local suppliers. Some have the familiar yellow petals with black centers but others have rich bronze, red or even chocolate colored petals with green, yellow or other colors in the center.
Gallardia or Blanket flower is another sure performer. The red and yellow flowers bloom for much of the summer. There are also several newer colors including some solid red cultivars and others. Add some goldenrod, iris, and poppies and your garden will be alive with color in the spring and into the summer.
Many of these perennials can be planted this fall for a showy garden next spring. Visit nurseries and local display gardens to enjoy their beauty and make selections for your own plantings. With a little effort, you can have a spectacular floral display and still conserve precious water and other resources.
Some perennials will bloom much better if you continue deadheading them all summer. Most perennials are reasonably pest free. Watch for spider mites which can become a problem if the weather is hot and dry.
