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mclem_gw

last spring the azaleas didn't bloom well . . .

mclem
17 years ago

Wondering what I can do now to help the blooms for spring 2007.

I don't know why the blooms weren't good in spring 2006, but I did add some of the azalea fertilizer (compounded esp. for azaleas, rhodies, camelias) around March 06. Should I put down more now or at another time. I can get pine needles for mulch to help out the clay soil of North Carolina.

I don't know the cultivar because they came with the house. Original planting in spring 1999.

Any suggestions? Thanks!

Comments (3)

  • morz8 - Washington Coast
    17 years ago
    last modified: 9 years ago

    The mulch is always a good idea...it will help to condition the soil, conserve moisture, and add to the needed acidity of the soil as it decomposes.

    Your azaleas have already set buds for Spring bloom.

    These aren't heavy feeders and have low nutritional requirements compared to most shrubs. Sometimes additional fertilizer itself can be the problem, producing foliage instead of flowers...and in the case of so much being added it burns roots, can cause chlorosis and overall decline of the plant.

    Most common reasons for few or no blooms are too much shade (has something grown up in the landscape to create more shade for your azaleas?), and drought in summer when they are setting buds for the next Springs flowers.

  • rhodyman
    17 years ago
    last modified: 9 years ago

    It is best to limit azalea feeding to before bloom (like you did) and after bloom, but light feeding is best unless the plants show symptoms of malnutrition.

    Besides shade and drought there are many other concerns:

    Failure to set flower buds may be a sign of too much health and vigor in a plant. One solution my be to prune the roots by cutting around the plant with a spade or moving the plant. This will check foliage growth and encourage production of flower buds. Application of nitrogen rich fertilizers are the main cause of vigor which suppresses flower bud production. Deadheading flowers as soon as they wilt can promote flower bud production. Too much shade, a cool wet summer, or inadequate phosphorus or potassium in the soil may also suppress flower bud production. There are a number of other reasons for a lack of flowers. The effect of each variable depends upon the variety of the plant. The effects include:

    * Pruning. The buds are formed in late summer and early fall so pruning then or later is not advisable since it will remove flower buds. New leaf buds will form in the spring, but new flower buds won't form until the next year.

    * Variety. Some plants will never bloom. Some rhododendrons that come from the seed of a hybrid plant will look good but will never produce flowers or will produce very poor flowers. To come true to the parent plant, a hybrid may be propagated by cuttings or tissue culture but not from seed. A good hybrid seedling only comes about once in a while. For that reason it is important to know that you are getting a good named variety or a good species.

    * Weather. Cold weather can kill flower buds. Usually you see the brown buds in the spring. Cold spells in the fall or spring can damage buds that are not hardened off. Bud blast (blooming in fall or winter) uses up good buds which are then not available at the normal blooming time.

    * Age. Most rhododendrons take 2 to 3 years to bloom from a rooted cutting unless forced. Some take longer and some bloom sooner. From seeds the plant may take 1 or 2 additional years.

    * Inspection. You can usually tell if the plant has ever bloomed. A rhododendron that has bloomed will have the seed pods on it unless it has been dead-headed. If dead-headed too late after blooming, new flower buds can be damaged. If in fact you see buds that died and never formed flowers, that may be caused by several problems:

    * Bud blast. Disease may attack the buds before they open. If it is a fungal infection, the dead bud will be covered with short hair-like structures.

    * Fall Blooming. Some causes of fall blooming include a dry summer and moist fall and/or warmer climates including a warm fall. For some reason, fall blooming is more common in Georgia according to Dr. Sandra McDonald. Plants which are not sufficiently hardened off or are exposed to unseasonable warm spells can start bloom prematurely. These blooms are seldom satisfactory and many times get frozen before opening fully. In any case, the seasonal bloom is lost. Avoid application of nitrogen after late spring, but phosphorus and potassium may be applied throughout the growing season. Application of nitrogen too late in the season can hinder hardening off in the fall.

    * Low temperatures. The buds could be flower buds that froze. Early frosts are especially distructive. Plants harden off progressively in the fall. If a frost occurs before hardening is complete, the frost can kill flower buds. Late frosts in the spring after dormancy is broken is also a problem. This is expecially true of early bloomers such as PJM that break dormancy very early. Cold climates may be too cold for many rhododendrons. Most rhododendrons have a low temperature at which the flower buds are damaged and will not produce flowers. It varies greatly from variety to variety and somewhat from season to season. Flower buds can also be damaged by cold, dry winds, particularly when warm winter weather is followed by a period of bitter cold.

    * Nutrients. Improper nutrients my be a problem that affects cold hardiness and flower bud set. A few things you can do are to fertilize with phosphorus (super-phosphate) per directions to increase hardiness and flower bud set. This can be done any time. Do not use nitrogen rich fertilizers as they may inhibit flower bud production and also reduce cold hardiness. Lawn fertilizers are notoriously high in nitrogen and should be kept away from flowering plants.

    * Acidity. Measure the pH and acidify if necessary. Flowers of sulfur (powdered sulfur) or iron sulfate are the best chemicals to use to increase the acidity [lower the pH]. Do not use aluminum sulfate since aluminum salts build up in the soil and eventually becomes toxic to many plants including rhododendrons and azaleas. If soil is too acid, the symptoms can be the same. Very acidic soil can prevent the roots from taking up nutrients. As many of my rhododendrons are planted in very acidic forest soil, an application of Dolomite and a light topdressing of mushroom manure in late spring is all they need. Sprinkle the lime on in late winter, very early spring. Don't overdo it - just a light sprinkle. If it is mid-spring, get the lime on right away so the rhododendron roots will be able to take up the soil nutrients in time for new growth. If you don't have rain, water it in well.

    * Protection. If the plants are wrapped in burlap during the winter, they may gain a few more degrees in hardiness.

    * Drought. When soil moisture is too low, the buds will not open. Watering will usually resolve this condition if detected soon enough. Also, summer drought with a moist fall can contribute to fall blooming.

    * Deer Damage. Deer and rabbits may eat many of the flower buds as they browse in the winter, particularly if the weather is harsh and other food is scarce.

    Here is a link that might be useful: How to grow rhododendrons and azaleas.

  • mclem
    Original Author
    17 years ago
    last modified: 9 years ago

    Well, there was a drought in 2005 so that could have contributed to it. they get afternoon/west sun -- maybe need more morning and less intense afternoon (it does get hot in NC). Never been pruned and I don't deadhead the blooms.

    I know there is a bunny around because my lirope is getting munched upon. Deer aren't an issue.

    So, maybe a root prune, add pine needles, fertilize in March 2007, deadhead spent blooms, and hope for the best?

    As an aside, after I moved into the house, I moved the azaleas and one ended up at my parent's house (I thought they were spaced too close together) about 10-15 miles away. The one at their house is doing much better than mine and I don't think my parents do anything to it. It has grown larger than mine. It gets dappled sun, more in the morning but does get some afternoon, and mine get full-on afternoon sun. Theirs is also in a raised bed that isn't full of compacted NC clay soil. Interesting how similar plants react differently.

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