Spiraea thunbergii ( Ogon Spirea )

Characteristics

Cultivar:	Ogon
Family:	Rosaceae
Size:	Height: 0 ft. to 6 ft. Width: 0 ft. to 5 ft.
Plant Category:	landscape, shrubs,
Plant Characteristics:	low maintenance,
Foliage Characteristics:	deciduous, semi-evergreen,
Foliage Color:	yellow-green to gold,
Flower Characteristics:	showy,
Flower Color:	whites,
Tolerances:

Requirements

Bloomtime Range:	Late Spring to Early Summer
USDA Hardiness Zone:	4 to 8
AHS Heat Zone:	Not defined for this plant
Light Range:	Sun to Full Sun
pH Range:	5.5 to 6.5
Soil Range:	Sandy Loam to Clay Loam
Water Range:	Normal to Moist

Plant Care

Fertilizing

How-to : Fertilization for Young Plants

Young plants need extra phosphorus to encourage good root development. Look for a fertilizer that has phosphorus, P, in it(the second number on the bag.) Apply recommended amount for plant per label directions in the soil at time of planting or at least during the first growing season.

How-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.

Light

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 : 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!

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.

Watering

Problems : 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 : 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.

Planting

How-to : Pruning Flowering Shrubs

It is necessary to prune your deciduous flowering shrub for two reasons: 1. By removing old, damaged or dead wood, you increase air flow, yielding in less disease. 2. You rejuvenate new growth which increases flower production.

Pruning deciduous shrubs can be divided into 4 groups: Those that require minimal pruning (take out only dead, diseased, damaged, or crossed branches, can be done in early spring.); spring pruning (encourages vigorous, new growth which produces summer flowers - in other words, flowers appear on new wood); summer pruning after flower (after flowering, cut back shoots, and take out some of the old growth, down to the ground); suckering habit pruning (flowers appear on wood from previous year. Cut back flowered stems by 1/2, to strong growing new shoots and remove 1/2 of the flowered stems a couple of inches from the ground) Always remove dead, damaged or diseased wood first, no matter what type of pruning you are doing.

Examples: Minimal: Amelanchier, Aronia, Chimonanthus, Clethra, Cornus alternifolia, Daphne, Fothergilla, Hamamelis, Poncirus, Viburnum. Spring: Abelia, Buddleia, Datura, Fuchsia, Hibiscus, Hypericum, Perovskia, Spirea douglasii/japonica, Tamarix. Summer after flower: Buddleia alternifolia, Calycanthus, Chaenomeles, Corylus, Cotoneaster, Deutzia, Forsythia, Magnolia x soulangeana/stellata, Philadelphus, Rhododendron sp., Ribes, Spirea x arguta/prunifolia/thunbergii, Syringa, Weigela. Suckering: Kerria

How-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.

Problems

Pest : Aphids

Aphids are small, soft-bodied, slow-moving insects that suck fluids from plants. Aphids come in many colors, ranging from green to brown to black, and they may have wings. They attack a wide range of plant species causing stunting, deformed leaves and buds. They can transmit harmful plant viruses with their piercing/sucking mouthparts. Aphids, generally, are merely a nuisance, since it takes many of them to cause serious plant damage. However aphids do produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface growth called sooty mold.

Aphids can increase quickly in numbers and each female can produce up to 250 live nymphs in the course of a month without mating. Aphids often appear when the environment changes - spring & fall. They're often massed at the tips of branches feeding on succulent tissue. Aphids are attracted to the color yellow and will often hitchhike on yellow clothing.

Prevention and Control: Keep weeds to an absolute minimum, especially around desirable plants. On edibles, wash off infected area of plant. Lady bugs and lacewings will feed on aphids in the garden. There are various products - organic and inorganic - that can be used to control aphids. Seek the recommendation of a professional and follow all label procedures to a tee.

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.

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.

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.

Diseases : Blight

Blights are cause by fungi or bacteria that kill plant tissue. Symptoms often show up as the rapid spotting or wilting of foliage. There are many different blights, specific to various plants, each requiring a varied method of control.

Miscellaneous

Glossary : Low Maintenance

Low maintenance does not mean no maintenance. It does mean that once a plant is established, very little needs to be done in the way of water, fertilizing, pruning, or treatment in order for the plant to remain healthy and attractive. A well-designed garden, which takes your lifestyle into consideration, can greatly reduce maintenance.

Glossary : Sandy Loam

Sandy Loam refers to a soil that drains well, with excellent air space, and evenly crumbled texture when squeezed in the hand. A good workable garden soil that benefits from added fertilizer and proper watering. Dark gray to gray-brown in color.

Glossary : Clayey Loam

Clayey loam refers to a soil that retains moisture well, without having a drainage problem. Fertility is high and texture good. Easily forms a ball when squeezed in the hand, and then crumbles easily with a quick tap of the finger. Considered an ideal soil. Usually a rich brown color.

Glossary : Deciduous

Deciduous refers to those plants that lose their leaves or needles at the end of the growing season.

Glossary : Semi-Evergreen

Semi-Evergreen: a plant that retains some or most of its foliage throughout the year.

Glossary : Shrub

Shrub: is a deciduous or evergreen woody perennial that has multiple branches that form near its base.

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 : Large Shrub

A shrub is considered large when it is over 6 feet tall.

Glossary : Pruning

Now is the preferred time to prune this plant.

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