Thursday, May 19, 2011

Creeping St. Johnswort, Evergreen Groundcover Of The Day


Hypericum calycinum
    Creeping St. Johnswort

Type    Groundcover, woody plant 
Hardy range    5A to 10A
Height    8" to 12" / 20cm to 30cm
Spread    36" to 5' / 90cm to 1.60m
Growth rate    Fast
Form    Spreading or horizontal
Exposure    Full shade to full sun
Persistence    Evergreen and semi-evergreen

Bloom Color    Yellow
Bloom Time    Summer

Environment
This plant tolerates drought.
This plant will grow in very 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    No change in fall color
This plant has attractive foliage.

Culture Notes
This plant can be invasive and is used often as a ground cover. Prefers full sun, but it will grow in shade.  Stem cuttings can be taken in the summer.  Often the stems will root if they touch the ground.  The seed can be collected in the fall. Plants perform poorly in the southern US, admirably in the northwest. Spreads rapidly by stolons once established.

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.

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