This evergreen perennial is more often grown as an annual in most gardens than not. Grown primarily for the unique variegated foliage, coleus are semi-succulent with toothed, angular leaves. ‘Purple Emperor’ has an open form and ruffled, blackish-purple leaves that occasionally have light green margins. Flowers appear in summer and are white and whorled, but are usually pinched off. Cutting propagated cultivars rarely flower, so pinching will not be necessary. Coleus may take sun or shade, but if grown in sun, should recieve ample water and be potted in a heavier mix. If plants get too leggy, simply cut back to encourage compact growth. Coleus root easily in water. If grown as a houseplant or winter annual in warmer areas, keep just moist. Fertilize monthly.
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CharacteristicsCultivar: Purple Emperor
Size: Height: 0 ft. to 0 ft.
Width: 0 ft. to 0 ft.
Plant Category: annuals and biennials, perennials,
Foliage Characteristics: evergreen,
Flower Characteristics: unusual,
Flower Color: whites,
Tolerances: heat & humidity,
Bloomtime Range: Mid Summer to Late Summer
USDA Hardiness Zone: 10 to 11
AHS Heat Zone: Not defined for this plant
Light Range: Shade to Full Sun
pH Range: 5.5 to 6.5
Soil Range: Sandy Loam to Clay Loam
Water Range: Normal to Moist
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 to Partial Shade
Full shade means there is little or no light in the growing zone. Shade can be the result of a mature stand of trees or shadows cast by a house or building. Plants that require full shade are usually susceptible to sunburn. Full shade beneath trees may pose additional problems; not only is there no light, but competition for water, nutrients and root space.
Partial shade means that an area receives filtered light, often through tall branches of an open growing tree. Root competition is usually less. Partial shade can also be achieved by locating a plant beneath an arbor or lathe-like structure. Shadier sides of a building are normally the northern or northeastern sides. These sides also tend to be a little cooler. It is not uncommon for plants that can tolerate full sun or some sun in cooler climates to require some shade in warmer climates due to stress placed on the plant from reduced moisture and excessive heat.
Conditions : Full to Partial Sun
Full sunlight is needed for many plants to assume their full potential. Many of these plants will do fine with a little less sunlight, although they may not flower as heavily or their foliage as vibrant. Areas on the southern and western sides of buildings usually are the sunniest. The only exception is when houses or buildings are so close together, shadows are cast from neighboring properties. Full sun usually means 6 or more hours of direct unobstructed sunlight on a sunny day. Partial sun receives less than 6 hours of sun, but more than 3 hours. Plants able to take full sun in some climates may only be able to tolerate part sun in other climates. Know the culture of the plant before you buy and plant it!
WateringConditions : Moist and Well Drained
Moist and well drained means exactly what it sounds like. Soil is moist without being soggy because the texture of the soil allows excess moisture to drain away. Most plants like about 1 inch of water per week. Amending your soil with compost will help improve texture and water holding or draining capacity. A 3 inch layer of mulch will help to maintain soil moisture and studies have shown that mulched plants grow faster than non-mulched plants.
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 : Planting and Removing Annuals
When planting annuals, begin by preparing the soil. Rototill rotted compost, soil conditioner, pulverized bark, or even builders sand into the existing soil and rake it smooth. Annuals grow quickly, so space them as recommended on plant tags. Remove plants from their containers or packs gently, being sure to keep as much soil as you can around the root ball. If the rootball is tight, loosen it a bit by gently separating white, matted roots with your fingers or a pocket knife. Plant at the same depth they were in the containers. Gently fill in around the plants, providing support but not cutting off air to the roots. Water the plants well.
Through the season, be sure to fertilize for optimal performance. Take special care to cut back or completely remove any diseased plants, as soon as you see there is a problem. At the end of the season, be sure to remove all plants and their root balls. Rake the bed well to prepare it for the next season's planting.
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 : Preparing Containers
Containers are excellent when used as an ornamental feature, a planting option when there is little or no soil to plant in, or for plants that require a soil type not found in the garden or when soil drainage in the garden is inferior. If growing more than one plant in a container, make sure that all have similar cultural requirements. Choose a container that is deep and large enough to allow root development and growth as well as proportional balance between the fully developed plant and the container. Plant large containers in the place you intend them to stay. All containers should have drainage holes. A mesh screen, broken clay pot pieces(crock) or a paper coffee filter placed over the hole will keep soil from washing out. The potting soil you select should be an appropriate mix for the plants you have chosen. Quality soils (or soil-less medias) absorb moisture readily and evenly when wet. If water runs off soil upon initial wetting, this is an indicator that your soil may not be as good as you think.
Prior to filling a container with soil, wet potting soil in the bag or place in a tub or wheelbarrow so that it is evenly moist. Fill container about halfway full or to a level that will allow plants, when planted, to be just below the rim of the pot. Rootballs should be level with soil line when project is complete. Water well.
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 : Mealybugs
Small, wingless, dull-white, soft-bodied insects that produce a waxy powdery covering. They have piercing/sucking mouth parts that suck the sap out of plant tissue. Mealybugs often look like small pieces of cotton and they tend to congregate where leaves and stems branch. They attack a wide range of plants. The young tend to move around until they find a suitable feeding spot, then they hang out in colonies and feed. Mealybugs can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.
Prevention and Control: Isolate infested plants from those that are not. Consult your local garden center professional or the Cooperative Extension office in your county for a legal insecticide/chemical recommendation. Encourage natural enemies such as lady beetles in the garden to help reduce population levels of mealy bugs.
Pest : Whiteflies
Whiteflies are small, winged insects that look like tiny moths, which attack many types of plants. The flying adult stage prefers the underside of leaves to feed and breed. Whiteflies can multiply quickly as a female can lay up to 500 eggs in a life span of 2 months. If a plant is infested with whiteflies, you will see a cloud of fleeing insects when the plant is disturbed. Whiteflies can weaken a plant, eventually leading to plant death if they are not checked. They can transmit many harmful plant viruses. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.
Possible controls: keep weeds down; use screening in windows to keep them out; remove infested plants away from non-infested plants; use a reflective mulch (aluminum foil) under plants (this repels whiteflies); trap with yellow sticky cards, apply labeled pesticides; encourage natural enemies such as parasitic wasps in the garden; and sometimes a good steady shower of water will wash them off the plant.
Pest : Scale Insects
Scales are insects, related to mealy bugs, that can be a problem on a wide variety of plants - indoor and outdoor. Young scales crawl until they find a good feeding site. The adult females then lose their legs and remain on a spot protected by its hard shell layer. They appear as bumps, often on the lower sides of leaves. They have piercing mouth parts that suck the sap out of plant tissue. Scales can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.
Prevention and Control: Once established they are hard to control. Isolate infested plants away from those that are not infested. Consult your local garden center professional or Cooperative Extension office in your county for a legal recommendation regarding their control. Encourage natural enemies such as parasitic wasps in the garden.