Spring is coming and many people will be tempted by the beautiful blossoms they encounter in garden centers and nurseries.

A rhododendron in full bloom is an impressive sight and can quickly transform a smitten gardener into a rhododendron purchaser and grower.

Many rhododendrons are indeed wonderful plants that can be welcome additions to a garden in our area, but keeping in mind some basic information may help prevent this burgeoning love affair from turning to disappointment

The genus Rhododendron is one of the largest among ornamental plants. There are more than 900 species and many more hybrids to choose from. The genus includes the widely recognized large-leaf rhododendrons (elepidote), small-leaf rhododendrons (lepidote), as well as evergreen and deciduous azaleas.

Rhododendrons are part of the Heath family (Ericaceae). Like other members of this family, rhododendrons tend to prefer moisture-retentive, but well-drained acidic soil. There is a wide variation within the genus in leaf size, leaf color, color of blossoms, time of bloom, height at maturity, distribution in the wild, hardiness and cultural requirements. Some varieties have aromatic flowers.

Rhododendrons range from low-growing plants that never exceed a few inches in height to trees that exceed 100 feet tall. Leaves vary in size from, less than an inch long to those more than 3 feet long. Some rhododendrons are tropical plants. Others are native to our area and can tolerate our extremes of summer heat and winter cold. Many are understory plants that prefer some protection from extremes of sun and wind.

Generally, the larger the leaf, the less tolerant the plant is of summer sun and drying winter winds. Many rhododendrons are attractive plants that would be welcome additions to the garden even if they never bloomed.

Some places will sell rhododendrons based only on the color of the blossom. This could lead to uncertainty about the plant's other characteristics. That beautiful pink blossom may be the perfect color for that special garden spot under your front picture window. However, that plant may not be the best choice if it is going to dwarf your house and conceal your window in 10 years. Your love of the bloom color may be diminished by the plant's monstrous size or by the task of annual pruning to keep it within your space constraints. By acquiring named plants the seller is familiar with (or that you could research yourself) you should be able to minimize such disappointments.

Unfortunately, much of our area has heavy, poorly drained soil with lots of clay. Soils that drain poorly can be improved by mixing in composted organic material. A raised rim of soil around the planting site will help collect water so it does not drain away too quickly.

Additionally, the use of a layer of organic mulch will help moderate temperatures for the roots and limit water loss. A thick layer of mulch will also discourage the growth of weeds that could compete with the shallow-rooted rhododendron. As the mulch deteriorates, it will help improve the soil. If your new plant is rootbound, you need to loosen the roots. Make sure the roots are ready to reach out and grow into their new home.

Generally rhododendrons prefer the soil to be slightly acidic, with the pH between 4.5 and 5.5. You can check your soil pH with soil test kits that are available at local garden centers and the Cooperative Extension Office.

The American Rhododendron Society offers a seed exchange and a journal published four times a year with a $28 membership. For information, check out http://www.rhododendron.org/.

Information about rhododendrons or other garden questions is also available through Master Gardeners and through your Cooperative Extension office.

Steve Wheeler lives in Ferguson Township where he has been gardening for the past 25 years. He began with the Master Gardener program in 1998.

For answers to your gardening questions, contact Master Gardeners by e-mail at centreext@psu.edu