Rhododendrons are popular among gardeners with their evergreen shrubbery and early blooms.
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Planting, Growing, and Pruning Rhododendrons and Azaleas
Planting
Most large-leafed varieties require dappled shade; avoid deep shade or full sun. A sunny spot that receives a few hours of shade is perfect. See regional guidelines below.
Soil should be well-drained, humus-rich, moist, and acidic (pH 4.5鈥6).
Azaleas and rhododendrons have shallow root systems and need moist soil and mulch to keep them from drying out. Amend planting areas with compost, peat moss, or a substitute, only if your soil is poor. Learn more about soil amendments and preparing soil for planting.
鈫 Not sure which hardiness zone you鈥檙e in? See the USDA map.
Planting in Cold or Temperate Regions (Zones 3 to 6)
- Plant in full sun to increase flowers and avoid mildew problems. Shrubs need a minimum of 6 hours of full sun daily.
- Plant on the sheltered side of a windbreak. If subjected to cold, dry winds, their leaves and buds dry out and die, especially during winter winds.
Planting in Warm or Hot Regions (Zones 7 to 11)
- Plant in a site that receives afternoon shade, especially in hot areas. In tropical zones, azaleas will bloom in full shade.
How to Plant Rhododendron & Azaleas
- Plant in spring or early fall.
- Space plants 2 to 6 feet apart, depending on their estimated mature size. Dig a hole as deep as the root ball and about twice as wide.
- Set new plants so that their top roots are at soil level or slightly below. If you plant them any deeper, the roots and trunks may rot.
- Fill the hole half full with soil, then water it well to settle the soil before filling it with the remainder of the soil.
Growing
How to Care for Rhododendron & Azaleas
- Mulch plants every spring with 2 to 5 inches of pine bark chips or pine needles to protect shallow roots and retain soil moisture. A lack of water reduces flower bud formation. Read more about using mulch.
- Tip: A common mistake is to create a so-called 鈥渕ulch volcano,鈥 where mulch is piled heavily around the trunk of the shrub. In fact, this can keep the trunk too wet and encourage rot. Always leave a few inches around the trunk free of mulch.
- See our guide to using mulch.
- Fertilize azaleas and rhododendrons sparingly and only when flower buds swell in the early spring, even if they are fall bloomers. Heavy applications of fertilizer will burn the plants鈥 roots.
- Water plants during the summer if rainfall is less than 1 inch per week.
- After flowering, deadhead where practical, to promote vegetative growth rather than seed production. Remove dead flowers from rhododendrons carefully; next year鈥檚 buds are just under the old heads and will start to develop shortly after flowering.
- Azaleas and rhododendrons may be transplanted at any time during the growing season, but they transplant most successfully during fall or early spring when they are dormant and temperatures are cool.
Winter Care for Rhododendrons
Rhododendrons are shallow-rooted plants; in cold regions, apply several inches of organic mulch around the base. In regions with severe winters, consider wrapping evergreen rhododendrons with burlap in the fall. Cold, dry winds will cause too much moisture evaporation from the leaves, which will wither and die. To help them recover from cold snaps, deeply water rhododendrons if there are warmer days. In the spring, prune out any dead or damaged branches and leaves.
Pruning Rhododendron & Azaleas
- In general, do not prune spring-flowering shrubs such as azaleas and rhododendrons. If you need to reduce height, prune after flowering in the spring.
- Otherwise, just remove dead, damaged, or diseased branches at any time of year.
- On young and old plants, simply snap off spent flower stalks by bending them over until they break away from their stems. Be careful not to damage growth buds at the base of each flower stalk.
Catherine Boeckmann
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My rhododendron flower, but are very sparse looking. Instead of looking lush and full like others I see, mine just look sad. Any advice?
An initial consideration for almost any failure to thrive is soil quality and pH. Rhododendrons and azaleas prefer acidic soil. That’s another way of describing the pH, and pH can be checked with an inexpensive soil tester. A good nurseryman/woman or your local extensive service can help you with that, too.
Rhodos and azaleas also like organic material in the soil and organic mulches on top. Give the plants a good dose of aged manure in late fall (or not al all). See more advice above about the conditions that enable rhodos to bloom at their best.
We hope this helps!
After our extremely warm Fall, my Rhody budded again. 蜜桃恋人 got cold, and this Spring, buds still remain, but it is doing nothing. Some leaves around the bottom are turning brown around the edges. It was planted a year ago. Should I remove the buds? Don't know what I should do with it.
I took a piece of my rododendrum and planted in another part of my yard. It has been five or six years, it is growing well but we have not had any flowers on it. Possible problems?
There are a number of reasons why rhodos do not bloom.
鈥 not enough light or too much light
鈥 too much fertilizer (especially too much nitrogen, which promotes foliage)
鈥 the age of the plant
鈥 weather: cold weather can kill buds
鈥 the variety: if it came form the seed of a hybrid plant, it will never produce (or produce poor) flowers.
鈥 planted too deep or has soil mounded beneath it. Roots are shallow and they need air; light mulch is adequate, once the plant is set.
鈥 You might also check the pH of the soil (do a test). See above for advice on that.
We hope this helps!
Hello - I have a nursery rhododendron growing to one side that must have favored growing towards the sun when on display. I'm planting it on front of my home and I'm thinking of planting the side with more leaves facing the home and letting the side with less blooms face out towards the sun to promote growth on that side to have a more symmetrical plant - Good idea? /Bad idea? Suggestions? Thanks, Gordon
One the face of it, Gordon, your idea sounds reasonable. However, we would also consider making a call to the nursery from which you purchased it. (It sounds like a recent purchase.) They may remember you and/or the plant and be able to give you advice. Some rhododendrons lean toward the shade…you want to be sure of your plant’s preference.
I have a small rhododendron in pot.
Planted last year when it flowered profusely.
This year it started off well, many buds but suddenly the leaves have drooped and the buds are looking a little yellow. It is a species (snow ??) which can grow in any type of soil according to the info on the plant. I have been watering it a lot and we have hard water here. Could that be the problem.
Help please.
Hard water could be the source of the problem. High alkalinity is common in hard water, and rhododendrons like acid, quite the opposite of alkalinity. Have your water tested for its pH, and help the plants with fertilizer (get something specifically for acid-loving plants, such as rhodos and azaleas). Your comment about 鈥渁ny type of soil鈥 is a little suspect here, too, though. Rhodos like acidic soil, so you should test it, too. Peat moss will help to add acidity to the soil (and retain moisture) and aged manure (mixed in in the fall, or not at all!) will help, too. For more on these details and others, see above.
I notices a green fungus? mold? on the stalks of the plant. It is in full bloom but I have never seen this before. Any suggestions?
