Oyama or Siebold Magnolia

Oyama sieboldii

Oyama magnolia (Magnolia sieboldii) is a 10-15 feet tall (and equal spread) deciduous tree or large shrub from eastern Asia. It prefers to grow in partial sunlight and in moist, well drained loamy soil (USDA zones 6 -8). Why are not more gardeners are not growing this small tree/shrub magnolia. Spring bloom is in May, avoiding the threat of frost injuring the flower buds of this later blooming magnolia.

White nodding egg-shaped flower buds appear in late June, and blooms appear intermittently thru most of the summer. The 1-3 inch wide saucer shaped flowers are white, centered by crimson stamens within. Oyama begins to flower at an early age.

The 3-6 inch long medium green foliage is first to appear in April, coated with a silvery pubescence. Leaves turn pale yellow before abscising in mid-autumn. Small pink fruits appear in late summer, and split open to reveal orange-red seeds in late September. Branch bark wood is light gray.

Feed magnolias with a slow release fertilizer in early spring. They benefit from annual mulching.  Pruning shrub to desired shape and size, and to remove dead or broken branches.

Oyama magnolia is an excellent pick for a small garden. It is available from  a few on-line specialty nurseries.

Hardier And More Colorful Hydrangeas

Summer Crush™ hydrangea

For over a quarter of a century, hydrangea breeders (Bailey's, Spring Meadows, and other nurseries) have introduced hardier, tougher, and more colorful bigleaf hydrangeas (Hydrangea macrophylla) that bloom on both new and old wood (USDA hardiness zones 5-8). 

Old wood flowers are set on last year’s growth and new wood flowers develop on current season's growth. It is important not to prune these hydrangeas late in the summer, as flower buds have already formed for the following spring.

Forver a quarter century, Proven Winners Colorchoice™ and Bailey’s Nurseries (Endless Summer™, Bloomstruck™, and Summer Crush™ brands) have introduced the newest hydrangea genetics. The Let's Dance™  series is worth a try in smaller gardens. A second option is to grow a different type of hydrangea Hydrangea serrata, or mountain hydrangea. New in this category from PW Colorchoice is the Tuff Stuff® series which have demonstrated superior bud hardiness and rebloom. Tuff Stuff Ah-Ha® reblooms heavily and has large doubled sepals on lacecap blooms, either pink or blue depending on soil (media) pH._­­­­­

A Perfect Year for Hortensia Hydrangeas

2010 has been an exceptional year for big leaf hydrangeas (Hydrangea macrophylla), also called “hortensia” hydrangeas. Consecutive year blooming rarely occurs here in the southern Appalachian region (USDA zones 6 and 7). ‘Nikko Blue” hydrangea, which has not bloomed for over 15 years, has been beautiful in my garden this summer.

Why have big leaf hydrangeas been so “on” this summer? I asked Dr. Sandra Reed, USDA hydrangea breeder at the TN State University Nursery Crops Research Station in McMinnville. Sandra’s response… “the weather”. The 2009 autumn was unusual. October and November temperatures gradually declined. The winter was cold and temps stayed cold, not fluctuating wildly. Across most areas a perfect spring followed with no severe freezes or frosts.

Finally, new hardier cultivars are available such as Endless Summer®, ‘Penny Mac’, and ‘Pia’ (lacecap type). These varieties are remontant, able to bloom on either old or new wood.

If your hydrangea(s) did not bloom this year, check the plant’s light exposure and nutrition. Hortensia types want a minimum of one-half day sunlight, preferably in the morning. Feed shrubs in early spring with a water soluble or slow-release fertilizer according the manufacturer’s package directions.

Plumleaf Azalea -This Gardener's Choice

Plumleaf azalea (Rhododendron prunifolium) has been blooming in my garden for the past ten days. This species is a late July - early August bloomer in northeast TN. The bright orange-red flowers of this native azalea light up any garden spot whether in full sun or partial shade. Provide some additional shade in southern climes (zones 7-b and 8). A dark red flower selection is available.

It grows in any well-drained soil type- sand, silt or clay. My two established shrubs receive little nutritional care. Shrubs are irrigated during severe drought periods, such as we are in currently.
Plumleaf azalea is an Alabama/southwest Georgia native, but is winter hardy in the southern Appalachian region (USDA zones 6-7), and further north (zone 5). It seems almost soil pH insensitive, although likely prefers an acidic range between 5.4 to 6.4. No diseases and insects pests trouble it. Flowers are not fragrant, but do attract numerous butterfly and bee pollinators.

Pruning is rarely done on my 15+ year old plant purchased at Callaway Gardens. Plumleaf azalea grows 8-10 feet tall, but I maintain it at 6 by 6 feet tall and wide. An errant branch is occasionally clipped back into the fold.

Vitex 'Shoal Creek'

Chastetree (Vitex agnus-castus) is an 8-10 foot deciduous shrub or 12-15 foot tall small tree (hardiness zone 6-b thru 8). Branching habit is dense and vase-shaped (upright). It blooms over most of the summer, from June thru late August. Its 12-18 inch long blue-violet flower spikes exude a slight herbal fragrance.

‘Shoal Creek’ is a leading cultivar. Cold hardiness appears better than most, although this has yet to be proven. The finger-like compound leaves are covered with pubescent hairs. Summer foliage color is grey-green, with a faint bluish cast more visible in May and June. Its disease resistant foliage and butterfly magnetism rates this vitex in a class on its own. Foliage is highly deer resistant.

Stem die-back may occur in a cold winter, but this fast grower recovers rapidly. Since flowering occurs on new growth, prune off all dead, injured and crowded branches before the start of May. Vitex prefers full sun, but will tolerate part sun. Plant in a loose, well-drained soil and keep adequately watered during the first year. Afterwards, vitex possesses very good drought tolerance.