Watch soil, light for rhodies

Q. What’s wrong with my azalea? What’s wrong with my rhododendron?

Mary from Boardman, and many more

A. Each year at the OSU Extension diagnostic clinic we get so many questions about azaleas and rhododendrons. Most of the time, these plants are planted in the wrong areas. These beautiful shrubs can be kept in Ohio if the proper planning and preparation are made to ensure their wellbeing. First, try to understand where these plants come from. If you have ever driven in the Smoky Mountains, you see the lush understory where azaleas and rhododendrons bloom effortlessly. That is a big clue as to what they need and want to thrive.

The cultural requirements for them are well-drained, light, acid soil with ample moisture during the growing season. You need to get a soil test to research the type of soil in your yard, as Ohio has clay that is soggy and heavy. To amend the soil you must add organic material (sphagnum, pine bark mulch, chopped old leaves), working it in well. Do not use sphagnum as a mulch as it crusts over and seals out moisture. Annual fertilizing for acid-loving plants is best.

They also require dappled sunlight in the summer, with shelter from winter winds, and no winter morning sunlight. This heats up the leaves and buds, leading to desiccation (brown, curling leaves). The north side of the yard, protected by a building, windbreak, fence, evergreens or other trees, is the best area to plant. They should not be planted under eaves, as this gets little or no rainfall to keep the ground moist. As well, leaching from basement cement blocks (or walkways) causes the pH to rise. Azaleas and rhododendrons love acidic soil, so when you prepare the soil you should add 50 percent organic medium, and sulfur. Work this down 12 inches (or use raised beds, but these must be watered often so as not to dry out). Do not use aluminum sulfate as the aluminum can damage the plants. Work up beds in the fall for spring planting, to release nutrients, and let the soil settle.

When planting you will either get a container or a root ball. If a container, soak the root ball for an hour before planting, remove container, and if needed score the root ball to free any pot bound roots in three to four locations. Loosen roots.

If the plant is in a root ball (burlap), soak it for 24 hours. Situate the ball in the planting hole and remove burlap. Plant at 1-11/2 inch above the soil line. Mulch — but not to the stem — and water well. Never tamp the soil down with your feet. This compacts the soil and can harm delicate root hairs. Yellow leaves mean they need amendments, and deadheading is the only other maintenance.

For more details on these beautiful plants, go to: http://go.osu.edu/rhod

Today’s answer is provided by Stephanie Hughes, OSU Extension master gardener volunteer. Call the office hot line at 330-533-5538 to submit your questions. Clinic hours vary this time of year due to the winter season.