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Knowledge to Grow by Karen Weiland - Rhododendrons

During a recent visit to my uncle’s house I marveled at how big his rhododendron bush was and commented that it must like that spot beside his front entry. He then pointed out to me the three leaves poking out of a stubby stem on the opposite side of the entry. “That,” he said, “is also a rhododendron planted at the same time as the other one.” I could feel his gardening pain as I also have some “rhodies” that are not exactly flourishing. So I made a mental note to do some research on them and here is what I found.

Rhodies, as I like to call them, can be a fussy, finicky bunch. They like well-drained, light, acidic soil, plenty of moisture during the growing season, and a sheltered area to grow in.

They like a site that is not windswept, provides dappled sun in the summer and little or no morning sun in the winter. With early morning winter sun, the leaves and buds tend to warm up, allowing water to transpire while the roots are frozen in the ground and cannot supply water to the leaves. This can lead to browning of the leaves and death of the buds.

One of the most important steps to take when planting a rhododendron is proper soil preparation. A soil test is recommended as rhodies like a pH of 4.5 to 5.5. If the soil pH needs to be adjusted, incorporate agricultural sulfur to the planting site at the rate of two pounds per 100 square feet of surface area. It is recommended that a person not use aluminum sulfate to acidify the soil as the aluminum residue could be harmful to the plant. Incorporate organic material such as pine bark mulch, compost or aged, chopped leaves into the rhodie bed to a depth of about 12 inches. It is recommended that the planting site be prepared in the fall to give the worked-up soil time to settle and the sulfur time to work its magic with planting then done in the spring. A cup of alfalfa meal, which contains a potent growth hormone, can be added to the hole at the time of planting.

At planting time, soak the roots, container and all, until it sinks to the bottom of the tub and no more bubbles rise to the top. If the plant is root-bound, score the root ball vertically, then gently loosen the roots with your fingers. Place the plant in the hole so that it sets 1½ inches above the soil line. Backfill with remaining soil and cover with mulch.

As always, Happy Gardening!