Azaleas need only a few feedings and the right soil acidity

COMMENTARY - Plant Doctor

May 25, 2008|By Tom Maccubbin, Special to the Sentinel

Question: Our azaleas and camellias have just produced a flush of growth. Is now the time to feed them? My fertilizer is not a slow-release product. Should I get one?

Answer: Azaleas need a feeding once monthly in March, May and August with a traditional fertilizer to look and grow their best. If you select a slow-release product, the application can be reduced to once or twice a year following label instructions.

Possibly the best idea is to use the fertilizer you have and then make the next product one of the slow-release types. Also, check the soil acidity. If the pH is in the 4.5 to 5.5 range, you can use any of the general fertilizers for shrubs. If the pH is above 5.5, select a product made specifically for azaleas and camellias. This helps make the soil acid and supplies nutrients that might be limited at the higher pHs.

What's with the worms?

Q: My cucumber plants look healthy, but the fruits have small worms that carve out the insides. What is the pest, and how is it controlled?

A: Your cucumber fruits are feeding an infestation of melon or pickle worms. These are the immature stage of a moth that also attacks squash and some melons. The larval stages produce a small entry hole into the fruits and often push out excreta.

Luckily, there are natural controls available, including the insecticides Thuricide and spinosad-containing products. They must be applied when the first signs of damage are noted; follow label instructions. If cucumber and squash fruits are affected, the parts with the worms can be cut off during preparation and the rest can be eaten. Melons are usually destroyed by the pests.

Where's the citrus fruit?

Q: I have several citrus trees that are 2 to 3 feet tall in containers and one that's 6 feet tall in the ground. They all bloom, but they don't set fruit. What do they need?

A: Your trees are youngsters when it comes to flowering and fruiting. Those in containers might set fruits when small because of the limited root space, but they are still too immature to be reliable. Citrus in the ground normally need to grow for five to seven years and more than 8 feet tall to be good producers. So in all cases, you are probably expecting too much too soon.

Make sure your trees are all growing in full sun, are kept moist and receive regular feedings. Trees in containers are going to need at least monthly feedings, or you may use one of the slow-release products following label instructions. Also, make sure these have large-enough containers to allow plenty of root growth so that they will produce a reasonable-size tree.

Tibouchina travails

Q: I have a tibouchina tree that was frozen during the winter. I trimmed it back twice to remove dead shoots. It is starting to grow, but there are no blooms. Do I need to trim it more?

A: Continue to remove any dead or declining portions but allow the healthy new shoots to grow. At first, you might produce a dense tibouchina bush, but the plant needs all the foliage it can grow to feed the roots and shoots.

In a few months, you can decide what to eliminate. At this time, the plant can be trimmed back to leave one or several trunks. Remove the limbs you do not need and allow the tree to continue growth.

Keep the soil moist and feed lightly every six to eight weeks with a shrub fertilizer, or use one of the slow-release products following label instructions. With good care, you can expect the first flush of blooms by mid- to late summer.

Zoysia still needs water

Q: Some of the zoysia plugs we planted in January are turning brown and appear to be dying in the full-sun areas. I thought zoysia was supposed to be drought tolerant and thrive in direct sun. What is wrong?

A: Zoysia, especially from plugs, is going to need an extended period of good care to be the drought-tolerant lawn you are expecting. Make sure the plugs and areas of growth from underground runners have adequate moisture to grow the dense established lawn in sunny locations. This might mean watering at least twice a week, plus some spot hand-watering in the real dry areas.

Once established, zoysia, like other drought-tolerant turfs (bermuda and bahia), can go weeks without water, but don't expect them to be a nice green color. These grasses turn brown and go into a semi-dormant state. When you water or the rains return, they will grow and regreen. So, if you want a good green zoysia lawn, you'll need to water once or twice a week.

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