For Release On Or After 03/18/11

By Dan Gill
LSU AgCenter Horticulturist

March kicks off the spring lineup of Louisiana Super Plants selections. The Louisiana Super Plants program is an LSU AgCenter educational and marketing campaign that highlights tough and beautiful plants that perform well in Louisiana landscapes. The first selection to be promoted this spring is a great new gardenia variety called Frostproof (Gardenia jasminoides Frostproof).

Gardenias are one of those plants we consider one of our Southern heritage plants. Although they are native to the Far East (like so many of our Southern heritage plants), we have grown them in the South for so many generations we feel they are part of our culture and gardening tradition.

Fragrance is one of the things that attract gardeners to this shrub. Gardenias produce single or double white flowers that emit a powerful scent. The fragrance of gardenias on the languid breezes of an early summer evening is about as Southern as it gets. Some find the strong fragrance a little overwhelming, but most gardeners will gladly bury their nose in a flower.

The lustrous dark green foliage is evergreen and attractive year round.

Gardenias are acid-loving shrubs that prefer a soil pH of 5.5 to 6. If you are preparing a bed for gardenias and the pH of your soil is above 7, you should add sulfur or other soil-acidifying agents to lower the pH.

When grown in soils that are too alkaline, gardenias have trouble absorbing the iron they need (all plants need iron to be healthy). This leads to a condition called iron chlorosis. It will appear primarily in the newer leaves. Typically, the veins of the leaves will be green while tissue between the veins is yellow or yellowish green. The entire plant may take on a yellowish cast. This looks different from old leaf drop and should not be confused with it.

For gardenias that are iron deficient, apply an iron fertilizer to provide available iron and a soil acidifier to lower the pH of the soil in the bed.

The Frostproof gardenia

The Frostproof gardenia was chosen for the Louisiana Super Plants program for a variety of reasons.

This evergreen shrub produces fragrant, double, velvety-white flowers heavily in May and then sporadically through the summer. This gardenia is known for its prolific flower production.

Frostproof, as its name implies, is more cold-hardy than other gardenias, although this is not as much of a factor here in Louisiana. Still, this gardenia can be counted on to hold up through even unusually cold north Louisiana winters.

Experience indicates Frostproof is tough, adaptable and not as finicky as some other gardenia varieties. March, while the weather is still cool, is an excellent time to plant hardy shrubs like Frostproof gardenias.

Gardenia shrubs can grow to be quite large – as big as 6 feet to 8 feet across by 6 feet to 8 feet tall. Growing about 5 feet tall and 4 feet wide, Frostproof is considered a compact gardenia that will fit in well where a smaller shrub is needed. The leaves are somewhat smaller than most other gardenia varieties, giving this gardenia an attractive, medium to fine texture.

About the Super Plants program

Home gardeners and professional horticulturists alike can benefit from using Louisiana Super Plants. Selected plants have a proven track record, having gone through several years of university evaluations and/or years of observations by landscape industry professionals. Louisiana Super Plants are “university tested and industry approved.”

The Louisiana Super Plants program has three parts. The first is to identify outstanding plants. The second is to make sure the plants are available at retail nurseries and garden centers. The third is to get the word out about these great plants to Louisiana gardeners.

Look for information about Louisiana Super Plants in newsletters, magazines, newspapers, TV segments, radio and on the Internet (www.LSUAgCenter.com/SuperPlants). In addition, when you visit your local nurseries, look for signs showing which plants are the Louisiana Super Plants selections.

In addition to Frostproof gardenia, two warm-season bedding plants and a small, summer-flowering tree are also Louisiana Super Plants selections for spring 2011.

Serena Series angelonia (Angelonia angustifolia) and Butterfly Series pentas (Pentas lanceolata) are beautiful, long-blooming additions to the summer flower garden. Serena angelonia grows in full sun and Butterfly pentas grow in full sun to part shade. Both will bloom from the time you plant them in late spring or early summer until first frost.

Vitex Shoal Creek (Vitex agnus-castus Shoal Creek) can be trained as a large shrub or small multi-trunked tree about 10 feet to 15 feet tall and wide. Shoal Creek vitex is more vigorous and produces larger flowers that have a deeper color than common vitex.