I'm trying to plant Azalea Trees for the first time, and I've been told they are temperamental and difficult to grow. I wanted to get opinions on these issues:
1) I was told to plant them in shade. In California, where the sun in summer might be 95 to 105 frequently, how many hours a day can the trees have direct sunlight?
2) I was told to use an acid soil. The instructions for that soil say to mix one part existing soil with two parts of the acid plant mix. How important is it to mix in with the existing soil, and can you just plant in the acid mix directly?
3) I know you should not use peat moss directly as the soil, but could you put in a base of peat moss well under the plant just to give it a reservoir of water that the roots could grow down to and across? Is there any harm in having a small top layer of peat moss, just to give a slow drip of water down to the roots from the top?
4) How often should you add fertilizer on the top soil layer?
They prefer a few hours of sun per day. They don't mind heat/sun but prefer cool roots, mulch w/ pine needles. Keep soil pH < 7. An acid plant mix is good. Using peat moss in the soil and/or as a mulch is good. After they bloom, prune if needed, and then fertilize monthly with an acid fertilizer until fall. Keep watch for insect damage. Select another plant if you have deer.
This depends on the variety. Most azaleas are definitely not tolerant of direct sunshine. However, the azaleas in my garden (adjacent to the San Fernando Valley and Thousand Oaks) do okay with only part shade.
I have three in the "southern Indica hybrids" group, a group specially developed for tolerance of direct sun. These are 'Pride of Dorking', 'Formosa', and 'George Taber'. I also have 'Inga', which appears to be in the "Belgian Indica group". "Monrovia hybrids" is another group that is sun-tolerant, but I don't have any of those.
I have one in the "Rutherfordiana hybrids" group -- 'Alaska' -- that sometimes seems to struggle.
You will eventually want the roots to grow beyond the original planting hole. Otherwise, the azalea will grow only in the hole as if it were growing in a flower pot. For the roots to grow beyond the hole, you should blend the planting mix with the native soil. This prevents the formation of a boundary between the two.
Since azaleas tend to be shallow-rooted, dig the hole twice as wide as the nursery container but only about 2 inches deeper. Place about two handsful each of gypsum and bone meal in the bottom of the hole. The gypsum will promote drainage into the soil below (azaleas need excellent drainage); the bone meal contains phosphorus, which will promote flowering. Stir the gypsum and bone meal into the soil at the bottom of the hole with a little of the acid plant mix. Then, plant the azalea with enough of the blended acid plant mix and native soil under it so that the root ball is about 2 inches above the natural soil surface. Use any of the remaining blend to sculpt a mound from the azalea out over the planting hole and even beyond.
Mulch well with leaves or other organic matter. I use the output from my office shredder. DO NOT FEED during the first year. Like camellias, azaleas actually prefer a lean soil.
Anything you use in planting (for ANY plant) should be blended somewhat with the native soil. Peat moss in particular will shed water and stay dry if it is alone and allowed to dry out. Thus, it should NOT be used as a mulch on top of the soil. Mixed with soil, peat moss will absorb water. The combination -- half native soil and half peat moss -- would make a great planting medium for azaleas and camellias.
I feed my azaleas once a year with a commercial azalea and camellia food. I do this right after the plants finish blooming.
Before they bloom, I might broadcast more gypsum over the entire bed. My soil tends to be heavy, sticky clay. Gypsum reacts chemically with clay to make it porous and less sticky.
If the azalea leaves appear chlorotic -- yellow-green with green veins
-- I LIGHTLY broadcast iron sulfate and soil sulfur on the bed. I do this at any time of the year.
I personally prefer bush azaleas instead of trees. The trees are quite artificial and must be staked to prevent the "trunk" from breaking. (I also prefer rose bushes instead of tree roses.)
I think this must be spot on advice as I'm following it accidentally.
Mine are planted in the shade under the cover of pines and heavily mulched with pine straw. I never water them (or for that matter feed them), but they are well established. They are known to be acid lovers and don't mind pruning.
They don't seem to mind heat, although 100's are rare here, we do get strings of them every few years.
They obviously love this kind of treatment as they are monsters (varieties vary in size) in the neighborhood of 10' * 10' wide. It's a real knockout when they are in bloom.
Azaleas are considered shrubs though some do get quite tall when they get very old.
Typically they need about 3 hours of sun a day or equivalent (on clear days) to bloom adequately. A with all things, some require more sun and some do quite well in the shade.
On of the best ways to plant azaleas in areas with alkaline soil is to use a raised bed with all acidic soil, no native soil. Azaleas have shallow roots, so if you place a raised bed, about 10 to 12 deep above he native soil, you should do OK. Drainage is most important.
Peat moss is a soil ammendment, not a soil. It rots and then you will have nothing, so do not treat it as a soil. Mix it with soil. Never use as a mulch either. It dries out easily and is useless. Its novelty is that it acts like a sponge, holding water while keeping the soil from being too wet. That is what it should be used for.
Fertilization is not necessary in most good soils. If you do fertilize, do so around bloom time in the spring and only use a good azalea granular fertilizer like Hollytone and use once per year at half the rate on the package. Watersoluable fertilizers like Miracid/MiracleGrow are only useful in a greenhouse where plants are fertilized with the watering system.
In warm climates, two things are very important, drainage and mulch. Good drainage is very important. Mulching keeps the roots moist and cool. Good drainage and mulching help prevent root rot which is a major problem in warm climates.
The only confusing thing in the above are these points:
1) If peat moss acts as a sponge, then why also say it dries quickly?
2) If the peat moss will eventually rot away to nothing, why use it mixed with soil? Or maybe the question becomes how often would it need to be replaced to counteract the tendency to rot away?
When used on the surface as a mulch, air and sun dry it out quickly since it is very porous and open.
When used in the soil as a soil amendment, it soaks up free water and just maintains an airy but moist under ground environment which is ideal for azaleas and other rhododendrons.
When used as a mulch, when it rots it forms a dust that blows away.
When used as a soil ammendment, when it rots it mixes with the soil forming a loam.
You don't mix anything with the soil on an established azalea plant. Azaleas have shallow root and when you disturb the soil, you disturb the roots, a bad idea. So the soil mix is designed to give the plants an optimum start and the when it stabilizes over time it should become a good acidic loam soil with good drainage.
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