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Rhodos for Novices

© Susan Ward

Rhododendrons hold a special place in my heart (as they do in the hearts of so many gardeners) for their beauty, versatility and low maintenance. Spring would be a much duller season without the splendid blaze of blooms that rhododendrons provide throughout the lower mainland.

While we tend to think of evergreen, large-leaved shrubs when we think of rhododendrons, the genus also includes dwarf smaller leaved shrubs, both evergreen and deciduous (which we commonly call azaleas). At the other extreme are rhodos that attain tree size, so it's important to find out what a particular rhododendron's mature size is before you bed it. There's also quite a range of hardiness within the genus; some are frost tender, another important consideration when you're choosing a plant.

Most rhodos prefer dappled shade (which makes them ideal candidates for planting around trees or by houses), but a fair number of them will tolerate full sun. They have to have acid soil; ground that's humus-rich and well drained is perfect. John Street (Rhododendrons, 1987, Globe Pequot Press) warns that rhodos will have chlorotic foilage and stunted growth if they're planted in alkaline soils or soil that is too acid; a pH reading of 5.6 is the best. To make your soil more acid if it's close to neutral, add plenty of peat or leaf mould and well-rotted cow manure, frequently mulching with the same.

Rhodos are surface-rooting; they need to be planted shallowly. Use a chipped bark mulch around the plants to conserve moisture and provide cover to keep weeds down; you don't want to cultivate around the rhodo's roots as even shallow hoeing could damage them. A high nitrogen feed in early spring will help flower bud development, but don't give them nitrogen in any form after spring to avoid damage to new soft growth.

The other yearly chore you'll have to perform is deadheading; rhodos that aren't deadheaded tend to flower well every other year, while those that are deadheaded should flower well every year, so you should remove the spent flower trusses after the plant has finished flowering. Wait until the flower heads have dried a bit, and then carefully break them off at the base, being careful not to damage the small growth buds surrounding the base.

I haven't met a rhodo lover yet who didn't have one particular rhodo she was looking for, no matter how many rhododendrons she already had. The web is a great place to look, because there's a lot of sites packed with pictures of rhodos in bloom so you can see exactly what your potential choice will look like at its peak. The Rhododendron Page, for instance, at http://www.netaxs.com/~mckenzi1/rhodo05.... has a huge and ever expanding database of rhodo species and hybrids, as well as information on the Tyler Arboretum (in Pennsylvania).