Growing Azaleas in DFW
We will have several varieties of azaleas in late Spring 2019.
Here's how to grow them:
Azaleas in the DFW area are easy to grow once you get the soil right. They require an acidic soil, 5.5 pH is good, and plenty of air to the roots. Both these requirements are satisfied with the use of pine bark in raised beds. Peat moss can also be mixed with the bark. They will not grow for very long in heavy alkaline soil. I take the plant out of the pot and set it on a few inches of mix, and then pile the mix around them. You will spend more on the planting mix than the plants, but at least there is no digging involved.
The second big problem is getting their roots to grow into your mix. The roots have been grown in containers and until the roots spread into the surrounding pine bark there is a chance of them drying out. Don't buy bargain plants that are extremely root-bound unless you are able to watch them often until they get established. Cut the roots on the bottom and spread them out before planting. Should they wilt you can water them with a hose. If they still wilt then the root ball is probable totally dry and you should let a hose drip on that plant for maybe an hour, or you can lift it up and dunk the roots in a bucket of water. By next summer they should be able to sustain themselves on the sprinkler system and not need as much attention.
Should the fall and winter be dry and warm they should be watered before any abrupt hard freeze. Azaleas, being evergreen, need moisture in the winter and if the pine bark is dry, or frozen, they will not be able to take the freeze as well. When the sun is shining, even when its cold, your azaleas need at least some moisture to keep their leaves from burning. Sudden drops in temperatures can cause the bark to split along the base of the plant when the azalea is getting hit by the sun. Therefore, the north side is the safest spot for them. Azaleas are very hardy though and bark split is not a common problem unless your plants are overfed or overwatered in the fall and therefor too vigorous right before the sudden cold.
Water your azaleas regularly in the summer for good growth. The plants in full sun will need the most. Wind also dries out the leaves making watering necessary. For best growth they will need a small amount of watering about every third or fourth day in the summer if it has not rained. I have some established azaleas in the hot afternoon sun in a peat/bark mixture which are watered just once a week.
Azaleas require little fertilizer. The pine bark has everything that they will need. However for faster growth and lusher looking plants you can fertilize with a balanced azalea food in April, May, June, and September. Too much nitrogen fertilizer is worse than none at all! You can burn the roots and foliage by over-fertilizing. Azaleas grown with lots of sun will need more fertilizer to keep them green. Note: Excessive watering can leach nutrients out of the leaves. The nicest ones I've seen in the area receive a product called Ironite once or twice a year. This product is safe to use. Since our water is alkaline this product helps to keep the bark acidic by supplying sulfur and it also really greens them up by supplying chelated Iron, some nitrogen, and other micro-nutrients. Without a soil test you will just have to judge how green the leaves are and apply Ironite when you think they could be a little greener. Cottonseed meal or Miracle Grow for Azaleas are good also.
Azaleas don't need pruning but if you like to shape them they should be pruned after flowering. This means May or June, depending on the variety. Every time you prune a branch you will get 3 or 4 side branches which will give you 3 or 4 more flowers. Long summer shoots can also be cut-back which will cause many side branches to form. Due not prune after about July 15 unless you don�t mind pruning off the flower buds! Azaleas form their flowers buds in late summer to fall and hold them through the winter and bloom in spring. Many azaleas lose some of their old leaves in the Fall and this is normal. In October some of the old leaves will turn yellow or red before dropping. Also, some Azaleas, primarily the red ones, turn a dark purple color in winter and this is also normal and creates a nice contrast in foliage.
Since your azaleas are planted correctly you should not have any fungus or disease problems. In the shade you will not have any insect problems either. Azaleas in a sunny location might attract Whiteflies. These insects do not seem to bother azaleas in the shade. Whiteflies are very small white insects that fly around like gnats when disturbed. They can damage your plants and can be sprayed with Orthene. Do not use Dursban on azaleas. The environmentally safest solution is to use a dormant oil spray like Superfine in late winter which will prevent eggs from hatching. One possible fungus you might see is blossom-end rot. This only affects your blooms and does not kill the plant. Blossom-end rot starts as small brown dots on your flowers and within a few days the whole flower turns a mushy brown mess. Spray with products containing Bayleton as the flowers are just opening.
Azaleas are long-lived plants. There are some in Japan that are over 600 years old. Basically all they need is correct planting, a little water, and annual mulching. Try to keep the pine bark moist and they will do fine. After about 10 years they probable will need to be lifted and replanted, rasied-up again with fresh azalea mix. If your azalea is not vigorous, lifting and replanting may help. This is done in the fall or late winter.
RHODODENDRONS IN HOT CLIMATES:
Azaleas are members of the rhododendron genus. Generally, Rhododendrons are more mountainous plants and like cool weather, whereas azaleas like it hot. Rhododendrons can be grown in Texas. You must select the right variety and plant them much higher-up than an azalea. Pure pine bark works well or mix in a little soil (about 10 per cent), but only if it is a sandy acid soil. Rhododendrons need a lot of air in their roots to stay alive in Texas. Try to create a cool and moist micro-climate. North and northeast exposure is the best. Only the R. hyperythrum hybrids can be grown like an azalea. Pine needles make great mulch. They prefer every other day waterings while getting established but later do fine in hot temperatures with a little sprinkel every 3 or 4 days on their shallow root system. Rhododendrons in Texas or the midwest, cannot take as much sun as an azalea but some morning sun is nice.
Some really good-doer Rhododendrons are: Roseum Elegans, Anah Kruschke, Black Eye, Yaku Angel, Anna Rose Whitney, Wheatley, Pink Pearl, Cynthia, Yaku Sunrise, Graf Zepplin, Catawbiense Grandiflorum, Nova Zembla and all the R. hyperythrm hybrids from John Thornton in Franklinton, LA, Pushetetappa Nursery. You'll probably have to mail order any of these plants but you might find some around town or in nurseries in Oklahoma or Arkansas.