Tuesday, April 10, 2012

Spring Parade Rhododendron, Evergreen Shrub, woody plant of The Day


Rhododendron (subgenus Rhododendron) 'Spring Parade'
    Rhododendron

Type    Shrub, woody plant
Hardy range    6A to 8A
Height    4' to 8' / 1.20m to 2.40m
Spread    6' to 10' / 1.80m to 3.00m
Growth rate    Slow
Form    Rounded
Exposure    Partial shade or partial sun
Persistence    Evergreen

Bloom Color    Red and salmon
Bloom Time    Spring and Summer

The flowers are very showy.

Environment
This plant will grow in moist soil.
Suitable soil is well-drained/loamy or sandy.
The pH preference is an acidic (less than 6.8) soil.

Leaf Color    Green
Fall Color    No change in fall color

Culture Notes
Partially shaded locations give good growth, provided drainage is adequate. Roots rot in soil that drains poorly. I (Dr. Gilman) have had no trouble transplanting these plants balled in burlap, although many are grown in containers. Pinch back the flowers after they have faded to eliminate the brown developing fruit if you wish. However, this is not essential for good flowering the following year. After all, these plants have flowered for years without our intervention. This plant is considered mostly allergy free and causes little or no allergy problems in most people.  Organic amendments in the backfill help establish plants quickly by encouraging roots to grow out of the container and into backfill soil. 'Spring Parade' is probably the best known cultivar in this group and is commonly planted.

Rhododendrons are ornamental, ericaceous, broad-leaved evergreens.  Azaleas belong to this genus, but many are not evergreen.  They grow best in shade or partial shade.  A south or southwest exposure increases the chance of winter injury to evergreen types when grown in northern climates.

Plant in an acidic, moist, well-drained soil with a pH between 4.5 and 6.5.  Transplanting balled and burlapped or potted plants is most successful.  The shallow root systems are easily injured by deep cultivation but benefit from mulching. Plants fail to absorb iron and have yellow leaves with green veins if the soil is not sufficiently acidic.  Finely ground sulphur can be added to the soil to increase acidity.  Have the soil tested before planting in order to determine the pH. Apply a 2:1:1 N:P:K ratio fertilizer two or three times each year before and after bloom and perhaps again as plants enter dormancy - timing is not as critical as previously believed.  Prevent winter burn in northern climates by avoiding exposed planting sites and by shading during winter.

Planting and establishing shrubs

The most common cause of young plant failure is planting too deep.  Plant the root ball no deeper than it was in the nursery.  In most instances, the root flare zone (point where the top-most root in the root ball originates from the trunk) should be located just above the landscape soil surface. Sometimes plants come from the nursery with soil over the root flare. If there is soil over this area, scrape it off.  The planting hole should be at least twice the width of the root ball, preferably wider.  In all but exceptional circumstances where the soil is very poor, there is no need to incorporate anything into the backfill soil except the loosened soil that came out of the planting hole.  Never place ANY soil over the root ball. If a row or grouping of plants is to be installed, excavating or loosening the soil in the entire bed and incorporating organic matter enhances root growth and establishment rate.

Weed suppression during establishment is essential.  Apply a 3-inch thick layer of mulch around the plant to help control weed growth.  Keep it at least 10 inches from the trunk.  If you apply it over the root ball, apply only a one or two inch layer.   This allows rainwater and air to easily enter the root ball and keeps the trunk dry.  Placing mulch against the trunk or applying too thick a layer above the root ball can kill the plant by oxygen starvation, death of bark, stem and root diseases, prevention of hardening off for winter, vole and other rodent damage to the trunk, keeping soil too wet, or repelling water.  Regular irrigation through the first growing season after planting encourages rapid root growth, which is essential for quick plant establishment.

Tuesday, April 3, 2012

Yellow Cosmos, Annual of The Day

Cosmos sulphureus 'Ladybird Scarlet'
    Sulphur Cosmos,  Yellow Cosmos

Type    Annual
Height    18" to 36" / 45cm to 90cm
Spread    24" / 60cm
Growth rate    Fast
Form    Upright or erect
Exposure    Full sun

Bloom Color    Red
Bloom Time    Summer

The flowers are suitable for cut flowers.

Environment
This plant tolerates drought.
This plant will grow in moist soil.
Suitable soil is well-drained/loamy.
The pH preference is  a neutral soil.

Leaf Color    Green
This plant has attractive foliage.

Culture Notes
Easy to grow from seed.  Used in naturalizing meadows and fields. Plants serve as butterfly nectar sources.


Monday, April 2, 2012

Carnaval Old Fashioned Weigela, Deciduous Shrub, woody plant of The Day


Weigela florida 'Courtalor(Carnaval™)'
    Old Fashioned Weigela,  Rose Weigela

Type    Shrub, woody plant
Hardy range    4B to 8A
Height    36" to 4' / 90cm to 1.20m
Spread    36" to 4' / 90cm to 1.20m
Growth rate    Average
Form    Rounded
Exposure    Full sun
Persistence    Deciduous

Bloom Color    Pink
Bloom Time    Spring

The flowers are very showy.

Environment
This plant tolerates some drought.
This plant will grow in dry soil.
Suitable soil is well-drained/loamy, sandy or clay.
The pH preference is an acidic to alkaline (less than 6.8 to more than 7.7) soil.

Leaf Color    Green
Fall Color    No change in fall color

Culture Notes
Weigela grows best in a sunny location and moist soil.  Shaded plants are straggly.  Weigela also dislikes crowding.  The growth rate is moderate and the shrub transplants well.  Some annual dieback and winter injury make annual pruning necessary.  Plants suffer in the deep south eastern part of the US.

Planting and establishing shrubs

The most common cause of young plant failure is planting too deep.  Plant the root ball no deeper than it was in the nursery.  In most instances, the root flare zone (point where the top-most root in the root ball originates from the trunk) should be located just above the landscape soil surface. Sometimes plants come from the nursery with soil over the root flare. If there is soil over this area, scrape it off.  The planting hole should be at least twice the width of the root ball, preferably wider.  In all but exceptional circumstances where the soil is very poor, there is no need to incorporate anything into the backfill soil except the loosened soil that came out of the planting hole.  Never place ANY soil over the root ball. If a row or grouping of plants is to be installed, excavating or loosening the soil in the entire bed and incorporating organic matter enhances root growth and establishment rate.

Weed suppression during establishment is essential.  Apply a 3-inch thick layer of mulch around the plant to help control weed growth.  Keep it at least 10 inches from the trunk.  If you apply it over the root ball, apply only a one or two inch layer.   This allows rainwater and air to easily enter the root ball and keeps the trunk dry.  Placing mulch against the trunk or applying too thick a layer above the root ball can kill the plant by oxygen starvation, death of bark, stem and root diseases, prevention of hardening off for winter, vole and other rodent damage to the trunk, keeping soil too wet, or repelling water.  Regular irrigation through the first growing season after planting encourages rapid root growth, which is essential for quick plant establishment.

Monday, March 26, 2012

Saucer Magnolia, DeciduousTree, Woody Plant of The Day





Magnolia x soulangiana 
Saucer Magnolia,  Chinese Magnolia

Type    Tree, woody plant
Hardy range    5A to 9A
Height    15' to 25' / 4.60m to 7.60m
Spread    15' to 25' / 4.60m to 7.60m
Growth rate    Slow
Form    Rounded and upright or erect
Exposure    Partial shade or partial sun to full sun
Persistence    Deciduous

Bloom Color    Pink and white
Bloom Time    Spring and Winter

The flowers are very showy.

Environment
This plant tolerates some drought.
This plant will grow in dry soil.
Suitable soil is well-drained/loamy, sandy or clay.
The pH preference is an acidic to neutral (less than 6.8 to 7.2) soil.

Leaf Color    Green
Fall Color    Yellow
This plant has attractive fall colors.

Culture Notes
Saucer Magnolia grows best in a sunny location in rich, moist but porous soil. It will tolerate poor drainage for only a short period of time.  Growth will be thin and leggy in a shaded spot but acceptable in part shade. Saucer Magnolia dislikes dry or alkaline soil but will otherwise grow very well in the city. Transplant from a field nursery in the spring, just before growth begins, and use balled and burlapped or containerized plants. Older plants do not like to be pruned and large wounds may not close well. Train plants early in their life to develop the desired form. Since flowers emerge very early, they are often damaged by frost.

Maintain adequate mulch area

Clear all turf away from beneath the branches and mulch to the drip line to reduce competition with turf and weeds.  This will allow roots to become established quickly and keep plants healthier. Train and prune the trunks and branches so they will not touch each other.  Remove some secondary branches on main branches with included bark, or those that are likely to develop it, as soon as possible. This reduces the likelihood of splitting from the tree later, when the tree has grown to become an important part of the landscape.  Locate the tree properly, taking into account the ultimate size, since the tree looks best if it is not pruned to control size.  The tree can enhance any landscape with its delightful spring flush of flowers.  It can be the centerpiece of your landscape if properly located. Flowers develop from buds formed the previous year.

Tree establishment specifications

Choose good quality trees for planting. The most common cause of young tree failure is planting too deep.  In most instances, the point where the top-most root in the root ball originates from the trunk (referred to as the root flare zone or root collar) should be located just above the soil surface.  You may have to dig into the root ball to find the root flare. If there is nursery soil over this area, scrape it off. Never place ANY soil over the root ball. The planting hole should be at least twice the width of the root ball, preferably wider because roots grow best in loose soil.  In all but exceptional circumstances where the soil is very poor, extensive research clearly shows that there is no need to incorporate any amendments into the backfill soil. Simply use the loosened soil that came out of the planting hole. Simply planting with the topmost portion of the root ball slightly higher than the surrounding soil might still install the tree too deep - be sure to locate the root flare.

Weed suppression during establishment is essential.  Apply a 3-inch thick layer of mulch to at least a six-foot diameter circle around the tree. This area should be at least two feet in diameter for each inch of tree trunk diameter and maintained during the establishment period.  Apply a thinner layer of mulch directly over the root ball but keep it at least 10 inches from the trunk. This allows rainwater, irrigation and air to easily enter the root ball and keeps the trunk dry.  Placing mulch against the trunk and applying too thick a layer above the root ball can kill the plant by oxygen starvation, death of bark, stem and root diseases, prevention of hardening off for winter, vole and other rodent damage to the trunk, keeping soil too wet, or repelling water.

Regular irrigation after planting encourages rapid root growth that is essential for tree establishment.  Trees provided with regular irrigation through the first growing season after transplanting require about 3 months (hardiness zones 9-11), 6 months (hardiness zones 7-8), or one year or more (hardiness zones 2-6) per inch of trunk diameter to fully establish roots in the landscape soil. Trees in desert climates may take longer to establish.  Trees that are under-irrigated during this establishment period (and most trees are) often require additional time to establish because roots grow more slowly.   Be prepared to irrigate through the entire establishment period, especially during periods of drought.

Irrigation also helps maintain and encourage the desirable dominant leader in the tree canopy on large-maturing trees.  Instead of a dominant leader, trees that are under-irrigated during the establishment period often develop undesirable, low, co-dominant stems and double leaders that can split from the tree later.

Unlike established plants, which do best with deep, infrequent irrigation, research clearly shows that recently transplanted trees and shrubs establish quickest with light, frequent irrigation.  For trees planted in spring or summer, provide one (cooler hardiness zones) to three irrigations (warmer hardiness zones) each week during the first few months after planting.  Daily irrigation in the warmest hardiness zones provides the quickest establishment.  Following the initial few months of frequent irrigation, provide weekly irrigation until plants are fully established.  With every irrigation, apply one (cool climates) to two (warm climates) gallons of water per inch trunk diameter (e.g. 2 to 4 gallons for a 2-inch tree) over the root ball only.  In most landscapes that receive more than 30 inches of rain or irrigation annually, if the mulch area is maintained weed-free, irrigation does not need to be applied outside of the root ball.  Never add water if the root ball is saturated.

In cooler hardiness zones, in all but the driest years, irrigation of spring- and summer-planted trees usually can be discontinued once fall color has begun. Irrigation of fall planted trees, however, should be continued until foliage has dropped from the deciduous trees in the region.  In warmer climates, irrigate fall-and winter-planted trees as described for the spring- and summer-planted trees.

In drier, desert climates there is benefit to be gained from applying additional irrigation outside of the root ball area. This is best done by making a large diameter berm four to six inches high, then filling it with water so it percolates into the soil.  For the first two years, irrigate twice each week through the spring, once per week in summer provided monsoons arrive, and twice each week again in fall if it remains warm.  Taper off watering to once or twice each month in winter and resume twice weekly next spring.  For years three to five, water twice per month in spring, summer, and fall and once or twice per month in winter.  During years five through seven, water once every three weeks in warm weather and once every six weeks in winter.  After this, the drought-tolerant desert trees should be able to survive on natural rainfall.

Trees with good, strong structure need no pruning at planting, except to remove broken twigs.  Do not remove branches to compensate for root loss - research has shown that this can be detrimental to establishment.