From the Desk of Ed Hume: Winter-Flowering Rhododendron

January 30, 2012 at 12:00 AM Leave a comment

It’s always nice to have a few plants in the garden that flower at unusual times. One rhododendron which blooms during the winter months is R. mucronulatum. This is one of the few varieties of rhododendrons that is deciduous, so the attractive flower clusters are quite noticeable. There are thousands of varieties of rhododendrons, so R. mucronulatum is sometimes overlooked.

R. mucronulatum has gorgeous flower clusters which consist of small flowers that are an attractive pinkish purple. Of course, it flowers before the new leaves appear, so it doesn’t really even look like a rhododendron. A bright pink variety, “Cornell Pink,” was recently developed by Cornell University.

R. mucronulatum flowers in late winter, but frost and cold weather may delay or interrupt its normal January or February flowering time.  I’ve grown this variety and would recommend that you plant it under the cover of a tree or in a place where there is overhead frost protection, so the flowers will last longer. Since it is a rhododendrons it should be planted in a semi-shady spot where it is protected from spot the hot mid-day sun. An ideal spot would be in a landscape bed with some later flowering varieties of rhododendrons, camellias, and azaleas.

Like all rhododendrons, this rhododendron should be planted so the top of the root ball is level with the soil surface. Planting or mulching too deeply may reduce flower development. At planting time I like to mix about 20% compost, peat moss, or other forms of organic humus with the existing soil.

Now before I suggest when and how to feed this or any other variety of rhododendron, let me make one thing clear: Never feed a rhododendron, or any plant, unless it needs additional nutrients. For example, native rhododendrons can go an entire lifetime without being fed. They simply rely on Mother Nature’s compost, and maintain a nice color and growth. Overfeeding can be as harmful as underfeeding.

How do you tell if a plant needs feeding? Off-color leaves, and stunted growth are often tell-tale indicators of the need for feeding. R. mucronulatum is fertilized on the same basis as the evergreen varieties. Use a rhododendron or evergreen plant food. The best time to feed them is late in the winter, from about mid-March to mid-May. Spread the fertilizer at the drip line of the plant, never under the plant, as it could burn the surface feeder roots.

This rhododendron variety is not readily available, so you may have to inquire at more than one place. However, you will find that the larger independent nurseries and garden centers are more apt to have them in stock or know where you can obtain them.


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