Monday, October 20, 2014

Featured Plant of The Day: 'Vulcan's Flame' Catawba Rhododendron

 Rhododendron catawbiense 'Vulcan's Flame'
    Catawba Rhododendron

Type    Shrub, woody plant
Hardy range    5A to 7B
Height    6' to 8' / 1.80m to 2.40m
Spread    6' to 8' / 1.80m to 2.40m
Growth rate    Slow
Form    Rounded
Exposure    Partial shade or partial sun
Persistence    Evergreen

Bloom Color    Red
Bloom Time    Spring

The flowers are very showy.

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

 Landscape Uses
-    Woodland garden
-    Border
-    Foundation planting
-    Massing
-    Specimen

Attributes and Features
-    Attracts birds
-    Attracts butterflies
-    Inconspicuous fruit

Culture Notes
Provide this plant with excellent drainage, organic soil and mulching. Do not cultivate around it, since it has surface roots and do not let the soil or mulch cover the stem. It is not salt tolerant nor drought tolerant and does not do well in sweeping winter winds. Rhododendron do well under the shade of canopy trees. This is certainly among the most vivid red selections.

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 acid, moist, well-drained soil with a pH between 4.5 and 6.5.  Transplanting balled and burlapped or potted plants is most successful. Organic amendments in the backfill help establish plants from containers quickly by encouraging roots to grow out of the container and into backfill soil.  The shallow root systems are easily injured by deep cultivation but benefit from mulching.  Remove the old flower clusters as the flowers fade.

Plants fail to absorb iron and have yellow leaves with green veins if the soil is not sufficiently acid.  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.