This cultivar has dense, fragrant dark purple to blue flowers. Spreading deciduous shrub grown for its clusters of up to 1 foot panicles throughout the summer. Graceful, arching branches bear pointed silvery-green leaves to 10 inches long. Reaches 10 feet tall and about 15 feet wide. Ideal for attracting butterflies. Combines well with other perennials, especially daylilies and shasta daisies. This is one plant that thrives on severe pruning.Important Info : Sometimes referred to as Buddleja davidii 'Black Knight'.
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CharacteristicsCultivar: Black Knight
Size: Height: 10 ft. to 15 ft.
Width: 10 ft. to 15 ft.
Plant Category: shrubs,
Foliage Characteristics: deciduous,
Flower Characteristics: fragrant, long lasting,
Flower Color: blues, purples,
Tolerances: deer, drought, heat & humidity, pollution, rabbits, seashore, slope,
Bloomtime Range: Early Summer to Mid Fall
USDA Hardiness Zone: 6 to 9
AHS Heat Zone: Not defined for this plant
Light Range: Sun to Full Sun
pH Range: 5.5 to 6.5
Soil Range: Mostly Sand to Some Clay
Water Range: Semi-Arid to Moist
FertilizingHow-to : Fertilization for Established Plants
Established plants can benefit from fertilization. Take a visual inventory of your landscape. Trees need to be fertilized every few years. Shrubs and other plants in the landscape can be fertilized yearly. A soil test can determine existing nutrient levels in the soil. If one or more nutrients is low, a specific instead of an all-purpose fertilizer may be required. Fertilizers that are high in N, nitrogen, will promote green leafy growth. Excess nitrogen in the soil can cause excessive vegetative growth on plants at the expense of flower bud development. It is best to avoid fertilizing late in the growing season. Applications made at that time can force lush, vegetative growth that will not have a chance to harden off before the onset of cold weather.
LightConditions : Sun
Sun is defined as the continuous, direct, exposure to 6 hours (or more) of sunlight per day.
Conditions : Light Conditions
Unless a site is completely exposed, light conditions will change during the day and even during the year. The northern and eastern sides of a house receive the least amount of light, with the northern exposure being the shadiest. The western and southern sides of a house receive the most light and are considered the hottest exposures due to intense afternoon sun.
You will notice that sun and shade patterns change during the day. The western side of a house may even be shady due to shadows cast by large trees or a structure from an adjacent property. If you have just bought a new home or just beginning to garden in your older home, take time to map sun and shade throughout the day. You will get a more accurate feel for your site's true light conditions.
Conditions : Types of Pruning
Types of pruning include: pinching, thinning, shearing and rejuvenating.
Pinching is removing the stem tips of a young plant to promote branching. Doing this avoids the need for more severe pruning later on.
Thinning involves removing whole branches back to the trunk. This may be done to open up the interior of a plant to let more light in and to increase air circulation that can cut down on plant disease. The best way to begin thinning is to begin by removing dead or diseased wood.
Shearing is leveling the surface of a shrub using hand or electric shears. This is done to maintain the desired shape of a hedge or topiary.
Rejuvenating is removal of old branches or the overall reduction of the size of a shrub to restore its original form and size. It is recommended that you do not remove more than one third of a plant at a time. Remember to remove branches from the inside of the plant as well as the outside. When rejuvenating plants with canes, such as nandina, cut back canes at various heights so that plant will have a more natural look.
Conditions : Light and Plant Selection
For best plant performance, it is desirable to match the correct plant with the available light conditions. Right plant, right place! Plants which do not receive sufficient light may become pale in color, have fewer leaves and a "leggy" stretched-out appearance. Also expect plants to grow slower and have fewer blooms when light is less than desirable. It is possible to provide supplemental lighting for indoor plants with lamps. Plants can also receive too much light. If a shade loving plant is exposed to direct sun, it may wilt and/or cause leaves to be sunburned or otherwise damaged.
Conditions : Full Sun
Full Sun is defined as exposure to more than 6 hours of continuous, direct sun per day.
WateringProblems : Creating a Water Ring
A water ring, sometimes called a water well, is a mound of compacted soil that is built around the circumference of a planting hole once a plant has been installed. The water ring helps to direct water to the outer edges of a planting hole, encouraging new roots to grow outward, in search of moisture. The height of the mound of soil will vary from a couple of inches for 3 gallon shrubs, to almost a foot for balled and burlapped trees, especially those planted on a slope. Mulch over the ring will help to further conserve moisture and prevent deterioration of the ring itself. Once a plant is established, the water ring may be leveled, but you should continue to mulch beneath the plant.
Problems : Waterlogged Soil and Solutions
Waterlogged soil occurs when more water is added to soil than can drain out in a reasonable amount of time. This can be a severe problem where water tables are high or soils are compacted. Lack of air space in waterlogged soil makes it almost impossible for soil to drain. Few plants, except for bog plants, can tolerate these conditions. Drainage must be improved if you are not satisfied with bog gardening. Over-watered plants have the same wilted leaves as under-watered plants. Fungi such as Phytophthora and Pythium affect vascular systems, which cause wilt.
If the problem is only on the surface, it maybe diverted to a drainage ditch. If drainage is poor where water table is high, install an underground drainage system. You should contact a contractor for this. If underground drains already exist, check to see if they are blocked.
French drains are another option. French drains are ditches that have been filled with gravel. It is okay to plant sod on top of them. More obtrusive, but a good solution where looks aren't as important, think of the French drain as a ditch filled with gravel. Ditches should be 3 to 4 feet deep and have sloping sides.
A soakway is a gravel filled pit where water is diverted to via underground pipes. This works well on sites that have compacted soil. Your soakway should be about 6'wide and deep and filled with gravel or crushed stone, topped with sand and sodded or seeded.
Keep in mind that it is illegal to divert water onto other people's property. If you do not feel that you can implement a workable solution on your own, call a contractor.
Tools : Watering Aides
No gardener depends 100% on natural rainfall. Even the most water conscious garden appreciates the proper hose, watering can or wand.
- Watering Cans: Whether you choose plastic of galvanized makes no difference, but do look for generous capacity and a design that is balanced when filled with water. A 2 gallon can (which holds 18 lbs. of water) is preferred by most gardeners and is best suited for outdoor use. Indoor cans should be relatively smaller with narrower spouts and roses (the filter head).
- Watering Hose: When purchasing a hose, look for one that is double-walled, as it will resist kinking. Quick coupler links are nice to have on ends of hoses to make altering length fast. To extend the life of your hose, keep it wound around a reel and stored in a shady area. Prior to winter freezes, drain hose.
- Sprayers: Are commonly thought of as devices for applying chemicals, but can really be a step saver for watering houseplants or small pots of annuals rather that dragging out a hose or making numerous trips with a watering can. The backpack sprayer is best suited for this. Take care not to use any kind of chemical in tanks used for watering!
- Sprinklers: Attached to the ends of garden hoses, these act as an economical irrigation system. Standing Spike Sprinklers are usually intended for lawns and deliver water in a circular pattern. Rotating Sprinklers deliver a circle of water and are perfect for lawns, shrubs and flower beds. Pulse-jet sprinklers cover large areas of ground in a pulsating, circular pattern. The head usually sits up on a tall stem, except for when watering lawns. Oscillating sprinklers are best for watering at ground level in a rectangular pattern.
Conditions : Water Conditions
When selecting Water Conditions, take into account the amount of water this particular area of your site receives naturally. If you have an irrigation system, select the default normal. Some sites may be naturally wet due to boggy areas by down spots or very dry due to a high sand content. By working with your site's natural conditions, you will reduce maintenance. Do note that even the most drought tolerant plant must first become established, so be willing to provide about 1 inch of water per week during the first year or two.
Conditions : Regular Moisture for Outdoor Plants
Water when normal rainfall does not provide the preferred 1 inch of moisture most plants prefer. Average water is needed during the growing season, but take care not to overwater. The first two years after a plant is installed, regular watering is important. The first year is critical. It is better to water once a week and water deeply, than to water frequently for a few minutes.
Conditions : Outdoor Watering
Plants are almost completely made up of water so it is important to supply them with adequate water to maintain good plant health. Not enough water and roots will wither and the plant will wilt and die. Too much water applied too frequently deprives roots of oxygen leading to plant diseases such as root and stem rots. The type of plant, plant age, light level, soil type and container size all will impact when a plant needs to be watered. Follow these tips to ensure successful watering:
* The key to watering is water deeply and less frequently. When watering, water well, i.e. provide enough water to thoroughly saturate the root ball. With in-ground plants, this means thoroughly soaking the soil until water has penetrated to a depth of 6 to 7 inches (1' being better). With container grown plants, apply enough water to allow water to flow through the drainage holes.
* Try to water plants early in the day or later in the afternoon to conserve water and cut down on plant stress. Do water early enough so that water has had a chance to dry from plant leaves prior to night fall. This is paramount if you have had fungus problems.
* Don't wait to water until plants wilt. Although some plants will recover from this, all plants will die if they wilt too much (when they reach the permanent wilting point).
* Consider water conservation methods such as drip irrigation, mulching, and xeriscaping. Drip systems which slowly drip moisture directly on the root system can be purchased at your local home and garden center. Mulches can significantly cool the root zone and conserve moisture.
* Consider adding water-saving gels to the root zone which will hold a reserve of water for the plant. These can make a world of difference especially under stressful conditions. Be certain to follow label directions for their use.
Conditions : Normal Watering for Outdoor Plants
Normal watering means that soil should be kept evenly moist and watered regularly, as conditions require. Most plants like 1 inch of water a week during the growing season, but take care not to over water. The first two years after a plant is installed, regular watering is important for establishment. The first year is critical. It is better to water once a week and water deeply, than to water frequently for a few minutes.
How-to : Reduce Watering
This plant requires less watering during winter months, so reduce watering from late November through early March.
PlantingHow-to : Planting Shrubs
Dig a hole twice the size of the root ball and deep enough to plant at the same level the shrub was in the container. If soil is poor, dig hole even wider and fill with a mixture half original soil and half compost or soil amendment.
Carefully remove shrub from container and gently separate roots. Position in center of hole, best side facing forward. Fill in with original soil or an amended mixture if needed as described above. For larger shrubs, build a water well. Finish by mulching and watering well.
If the plant is balled-and-burlapped, remove fasteners and fold back the top of natural burlap, tucking it down into hole, after you've positioned shrub. Make sure that all burlap is buried so that it won't wick water away from rootball during hot, dry periods. If synthetic burlap, remove if possible. If not possible, cut away or make slits to allow for roots to develop into the new soil. For larger shrubs, build a water well. Finish by mulching and watering well.
If shrub is bare-root, look for a discoloration somewhere near the base; this mark is likely where the soil line was. If soil is too sandy or too clayey, add organic matter. This will help with both drainage and water holding capacity. Fill soil, firming just enough to support shrub. Finish by mulching and watering well.
ProblemsPest : Spider Mites
Spider mites are small, 8 legged, spider-like creatures which thrive in hot, dry conditions (like heated houses). Spider mites feed with piercing mouth parts, which cause plants to appear yellow and stippled. Leaf drop and plant death can occur with heavy infestations. Spider mites can multiply quickly, as a female can lay up to 200 eggs in a life span of 30 days. They also produce a web which can cover infested leaves and flowers.
Prevention and Control: Keep weeds down and remove infested plants. Dry air seems to worsen the problem, so make sure plants are regularly watered, especially those preferring high humidity such as tropicals, citrus, or tomatoes. Always check new plants prior to bringing them home from the garden center or nursery. Take advantage of natural enemies such as ladybug larvae. If a miticide is recommended by your local garden center professional or county Cooperative Extension office, read and follow all label directions. Concentrate your efforts on the undersides of the leaves as that is where spider mites generally live.
Pest : Caterpillars
Caterpillars are the immature form of moths and butterflies. They are voracious feeders attacking a wide variety of plants. They can be highly destructive and are characterized as leaf feeders, stem borers, leaf rollers, cutworms and tent-formers.
Prevention and Control: keep weeds down, scout individual plants and remove caterpillars, apply labeled insecticides such as soaps and oils, take advantage of natural enemies such as parasitic wasps in the garden and use Bacillus thuringiensis (biological warfare) for some caterpillar species.
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.
MiscellaneousConditions : Deer Tolerant
There are no plants that are 100% deer resistant, but many that are deer tolerant. There are plants that deer prefer over others. You will find that what deer will or will not eat varies in different parts of the country. A lot of it has to do with how hungry they are. Most deer will sample everything at least once, decide if they like it or not and return if favorable. A fence is the good deer barrier. You may go for a really tall one (7 to 8 feet), or try 2 parallel fences, (4 to 5 feet apart). Use a wire mesh fence rather than board, since deer are capable of wiggling through a 12 inch space.
Conditions : Pollution Tolerant
Air pollution is becoming a bigger problem each day. Pollutants in our air damage plants. The plants are damaged by absorbing sulfur dioxide, ozone, peroxyacetyl nitrate, ethylene, and nitrogen dioxide through their pores. Cell membrane damage may result in leaf drop, blotched or burnt looking leaves, or off-colored tissue between veins. Vehicles and industrial processes are the key culprits and conditions worsen on hot summer days. Though planting only pollution tolerant plants is not the solution to this problem, it is a visual band aid. Your Cooperative Extension Service may have a list of plants that are more pollution tolerant in your area.
Conditions : Rabbit Tolerant
As cute as they are, rabbits can really damage a vegetable garden. Young, tender lettuce plants seem to be their favorite. If a free-roaming dog is not a possibility for you, consider installing raised vegetable beds and covering tender shoots with netting. If you have ample room, you can opt to plant enough for you and the bunnies. Scents don't always repel animals, as they get used to them and are often washed off in the rain.
Conditions : Slope Tolerant
Slope tolerant plants are those that have a fibrous root system and are often plants that prefer good soil drainage. These plants assist in erosion control by stabilizing/holding the soil on slopes intact.
Glossary : Butterfly Attracting
Many plants, perennials being the largest group, attract butterflies. When you add butterfly attracting plants to your garden, not only do you get to enjoy these winged wonders, but you provide habitats for their survival, as well. Yellows and reds seem to be favorite flower colors, while some plants offer food and shelter for laying eggs on. To complete your habitat, don't forget to add a shallow dish of water.
Conditions : Erosion Control
Plants that help to control erosion have fibrous root systems that help to keep soil intact. Leaves and the overall form of a plant can prevent erosion by breaking up water droplets before they hit the ground, lessening splashing and runoff.
Glossary : Deciduous
Deciduous refers to those plants that lose their leaves or needles at the end of the growing season.
Glossary : Shrub
Shrub: is a deciduous or evergreen woody perennial that has multiple branches that form near its base.
Glossary : Fragrant
Fragrant: having fragrance.
Conditions : Site Conditions
When setting criteria for site conditions, check boxes that apply to your planting area. This will narrow the search for appropriate plants. Naturally, you'll need to select a USDA Hardiness Zone. Selecting a specific soil type and pH are just as important as light and water conditions because they enable a search that will find plants best suited to your site.
Glossary : pH
pH, means the potential of Hydrogen, is the measure of alkalinity or acidity. In horticulture, pH refers to the pH of soil. The scale measures from 0, most acid, to 14, most alkaline. Seven is neutral. Most plants prefer a range between 5.5 and about 6.7, an acid range, but there are plenty of other plants that like soil more alkaline, or above 7. A pH of 7 is where the plant can most easily absorb the most nutrients in the soil. Some plants prefer more or less of certain nutrients, and therefore do better at a certain pH.
Glossary : Plant Characteristics
Plant characteristics define the plant, enabling a search that finds specific types of plants such as bulbs, trees, shrubs, grass, perennials, etc.
Glossary : Large Shrub
A shrub is considered large when it is over 6 feet tall.
Glossary : Flower Characteristics
Flower characteristics can vary greatly and may help you decide on a ""look or feel"" for your garden. If you're looking for fragrance or large, showy flowers, click these boxes and possibilities that fit your cultural conditions will be shown. If you have no preference, leave boxes unchecked to return a greater number of possibilities.
Glossary : Foliage Characteristics
By searching foliage characteristics, you will have the opportunity to look for foliage with distinguishable features such as variegated leaves, aromatic foliage, or unusual texture, color or shape. This field will be most helpful to you if you are looking for accent plants. If you have no preference, leave this field blank to return a larger selection of plants.
Glossary : Soil Types
A soil type is defined by granule size, drainage, and amount of organic material in the soil. The three main soil types are sand, loam and clay. Sand has the largest particle size, no organic matter, little to no fertility, and drains rapidly. Clay, at the opposite end of the spectrum, has the smallest particle size, can be rich in organic matter, fertility and moisture, but is often unworkable because particles are held together too tightly, resulting in poor drainage when wet, or is brick-like when dry. The optimum soil type is loam, which is the happy median between sand and clay: It is high in organic matter, nutrient-rich, and has the perfect water holding capacity.
You will often hear loam referred to as a sandy loam (having more sand, yet still plenty of organic matter) or a clay loam (heavier on the clay, yet workable with good drainage.) The addition of organic matter to either sand or clay will result in a loamy soil. Still not sure if your soil is a sand, clay, or loam? Try this simple test. Squeeze a handfull of slightly moist, not wet, soil in your hand. If it forms a tight ball and does not fall apart when gently tapped with a finger, your soil is more than likely clay. If soil does not form a ball or crumbles before it is tapped, it is sand to very sandy loam. If soil forms a ball, then crumbles readily when lightly tapped, it's a loam. Several quick, light taps could mean a clay loam.
Glossary : Drought Tolerant
Very few plants, except for those naturally found in desert situations, can tolerate arid soils, but there are plants that seem to be more drought tolerant than others. Plants that are drought tolerant still require moisture, so don't think that they can go for extended period without any water. Drought tolerant plants are often deep rooted, have waxy or thick leaves that conserve water, or leaf structures that close to minimize transpiration. All plants in droughty situations benefit from an occasional deep watering and a 2-3 inch thick layer of mulch. Drought tolerant plants are the backbone of xeriphytic landscaping.