This short-lived perennial, often treated as an annual in colder climates, is grown primarily for its pretty, tubular, two-lipped flowers, coming in all colors but blue and yellow. The leaves are narrow and lance shaped. Penstemons like dry, but rich soil. They are mid summer bloomers, attract hummingbirds, and will keep your garden exciting after the spring colors have faded away. P. ambiguus bears profusely, from early summer to early fall, phlox-like, white to rose-pink flowers, with rose-purple reverses.
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Size: Height: 0 ft. to 2 ft.
Width: 0 ft. to 1.67 ft.
Plant Category: perennials,
Plant Characteristics: low maintenance,
Foliage Characteristics: medium leaves,
Flower Characteristics: old fashioned/heritage, showy,
Flower Color: pinks, whites,
Tolerances: deer, drought, rabbits,
Bloomtime Range: Early Summer to Early Fall
USDA Hardiness Zone: 4 to 9
AHS Heat Zone: Not defined for this plant
Light Range: Part Shade to Full Sun
pH Range: 5 to 7.5
Soil Range: Some Sand to Some Clay
Water Range: Dry to Normal
FertilizingHow-to : Fertilization for Annuals and Perennials
Annuals and perennials may be fertilized using: 1.water-soluble, quick release fertilizers; 2. temperature controlled slow-release fertilizers; or 3. organic fertilizers such as fish emulsion. Water soluble fertilizers are generally used every two weeks during the growing season or per label instructions. Controlled, slow-release fertilizers are worked into the soil ususally only once during the growing season or per label directions. For organic fertilizers such as fish emulsion, follow label directions as they may vary per product.
LightConditions : Full Sun
Full Sun is defined as exposure to more than 6 hours of continuous, direct sun per day.
WateringHow-to : Xeriscaping
Xeriscaping is a method of planting which promotes naturally drought tolerant plants and water saving methods. Much consideration is given not only to the plants chosen for the design, but the design itself. Lawns are greatly decreased in size and usually located in the center of plantings at a lower grade as to catch any runoff. Shrubs requiring the most water, are conservatively used and thoughtfully placed, where they may be easily watered, preferably from runoff, and moisture conserved. There is a strong emphasis on using native plants, which a purist will do exclusively. At the very least, improved cultivars of natives are highly recommended.
Irrigation maybe used to supplement watering, but takes a creative turn in the form of drip systems and recycled catch water. Organic mulches in the form of compost, straws, and barks are also used to retain as much water as possible. In extremely dry areas, it is not uncommon for gravel and rocks to serve as the mulch.
A xeriphytic landscape is one that takes your particular site into consideration. A plant that maybe considered low water usage in one area of the country, may not be in another area, due to climatic stresses.
Conditions : Dry
Dry is defined as an area that regularly receives water, but is fast draining. This results in a soil that is often dry to a depth of 18 inches.
Conditions : Dry Plants
Dry plants do not tolerate water logged soils and require very little water. Many cacti and succulents fall into this group. Water only when soil becomes completely dry. When watering, do so slowly for a long period of time so that topsoil does not wash away and so that soil has ample time to become moist enough to accept water. It is much better to water for a long time and less frequently allowing soil to dry out completely between waterings.
PlantingHow-to : Preparing Garden Beds
Use a soil testing kit to determine the acidity or alkalinity of the soil before beginning any garden bed preparation. This will help you determine which plants are best suited for your site. Check soil drainage and correct drainage where standing water remains. Clear weeds and debris from planting areas and continue to remove weeds as soon as they come up.
A week to 10 days before planting, add 2 to 4 inches of aged manure or compost and work into the planting site to improve fertility and increase water retention and drainage. If soil composition is weak, a layer of topsoil should be considered as well. No matter if your soil is sand or clay, it can be improved by adding the same thing: organic matter. The more, the better; work deep into the soil. Prepare beds to an 18 inch deep for perennials. This will seem like a tremendous amount of work now, but will greatly pay off later. Besides, this is not something that is easily done later, once plants have been established.
How-to : Pinching and Thinning Perennials
Once you plant a perennial, it does not mean that you will enjoy years of maintenance-free gardening. Perennials need to be cared for just like any other plant. One thing that distinguishes perennials is that they tend to be active growers that have to be thinned out occasionally or they will loose vigor.
As perennials establish, it is important to prune them back and thin them out occasionally. This will prevent them from completely taking over an area to the exclusion of other plants, and also will increase air circulation thereby reducing the incidence of diseases like botrytis and powdery mildew.
Many species also flower abundantly and produce ample seed. As blooms fade it is advisable to deadhead your plant; that is, to remove spent flowers before they form seed. This will prevent your plants from seeding all over the garden and will conserve the considerable energy it takes the plant to produce seed.
As perennials mature, they may form a dense root mass that eventually leads to a less vigorous plant. It is advisable to occasionally thin out a stand of such perennials. By dividing the root system, you can make new plants to plant in another area of the garden or give away. Also root pruning will stimulate new growth and rejuvenate the plant. Most perennials may be successfully divided in either spring or fall. Do a little homework; some perennials do have a preference.
How-to : Planting Perennials
Determine appropriate perennials for your garden by considering sun and shade through the day, exposure, water requirements, climate, soil makeup, seasonal color desired, and position of other garden plants and trees.
The best times to plant are spring and fall, when soil is workable and out of danger of frost. Fall plantings have the advantage that roots can develop and not have to compete with developing top growth as in the spring. Spring is more desirable for perennials that dislike wet conditions or for colder areas, allowing full establishment before first winter. Planting in summer or winter is not advisable for most plants, unless planting a more established sized plant.
To plant container-grown plants: Prepare planting holes with appropriate depth and space between. Water the plant thoroughly and let the excess water drain before carefully removing from the container. Carefully loosen the root ball and place the plant in the hole, working soil around the roots as you fill. If the plant is extremely root bound, separate roots with fingers. A few slits made with a pocket knife are okay, but should be kept to a minimum. Continue filling in soil and water thoroughly, protecting from direct sun until stable.
To plant bare-root plants: Plant as soon as possible after purchase. Prepare suitable planting holes, spread roots and work soil among roots as you fill in. Water well and protect from direct sun until stable.
To plant seedlings: A number of perennials produce self-sown seedlings that can be transplanted. You may also start your own seedling bed for transplanting. Prepare suitable planting holes, spacing appropriately for plant development. Gently lift the seedling and as much surrounding soil as possible with your garden trowel, and replant it immediately, firming soil with fingertips and water well. Shade from direct sun and water regularly until stable.
ProblemsPest : Slugs and Snails
Slugs and snails favor moist climates and are mollusks, not insects. They can be voracious feeders, eating just about anything that is not woody or highly scented. They may eat holes in leaves, strip entire stems, or completely devour seedlings and tender transplants, leaving behind tell-tale silvery, slimy trails.
Prevention and control: Keep your garden as clean as possible, eliminating hiding places such as leaf debris, over-turned pots, and tarps. Groundcover in shady places and heavy mulches provide protection from the elements and can be favorite hiding places. In the spring, patrol for and destroy eggs (clusters of small translucent spheres) and adults during dusk and dawn. Set out beer traps from late spring through fall.
Many chemical controls are available on the market, but can be poisonous and deadly for children and pets; take care when using them - always read the label first!
Fungi : Powdery Mildew
Powdery Mildew is usually found on plants that do not have enough air circulation or adequate light. Problems are worse where nights are cool and days are warm and humid. The powdery white or gray fungus is usually found on the upper surface of leaves or fruit. Leaves will often turn yellow or brown, curl up, and drop off. New foliage emerges crinkled and distorted. Fruit will be dwarfed and often drops early.
Prevention and Control: Plant resistant varieties and space plants properly so they receive adequate light and air circulation. Always water from below, keeping water off the foliage. This is paramount for roses. Go easy on the nitrogen fertilizer. Apply fungicides according to label directions before problem becomes severe and follow directions exactly, not missing any required treatments. Sanitation is a must - clean up and remove all leaves, flowers, or debris in the fall and destroy.
Fungi : Leaf Spots
Leaf spots are caused by fungi or bacteria. Brown or black spots and patches may be either ragged or circular, with a water soaked or yellow-edged appearance. Insects, rain, dirty garden tools, or even people can help its spread.
Prevention and Control: Remove infected leaves when the plant is dry. Leaves that collect around the base of the plant should be raked up and disposed of. Avoid overhead irrigation if possible; water should be directed at soil level. For fungal leaf spots, use a recommended fungicide according to label directions.
Diseases : Southern Blight
Plants with Southern blight have lesions on the stem at, or near, the soil line. These lesions develop rapidly, girdling the stem and resulting in a sudden and permanent wilting of the plant. High temperatures (above 85 degrees F, 29 degrees C) favor the disease. The fungus attacks a wide range of plants and survives for long periods in soil. To control, treat with a recommended fungicide according to label directions.
MiscellaneousGlossary : U. S. Natives
Native plants require lower maintenance and usually have less pest problems. They are key components in the xeriphytic landscape and backyard wildlife habitat. Select your region and the search will look for all plants in the database that are native to your area.