Trees: Azaleas turning yellow

Ok, what's the deal? My azaleas are turning yellow and leaves are dropping off. What should I do?! Help! Please....

Smiln, are the leaves yellow with green veining? That usually means a soil pH imbalance of some sort, and they can't take up iron because of it.

At our last home, we had some beautiful azaleas (if I do say so myself), and every spring AFTER they bloomed, the leaves would get pale-looking. So here's what I did to restore them:

1. Add more peat. Brick home = lots of mortar and lime in the soil. So we essentially created a trench of pure peat to plant the azaleas in. Each spring, I'd add more peat, and sometimes gently lift up the azaleas to get some more peat under them, if they had seemed to settle during the winter (they like to be high and well-drained.)

2. Fertilize with an azalea-specific fertilizer. Scratch it in around the drip line, carefully (roots are shallow.)

I know you're warmer than me, but have your azaleas bloomed yet this spring? As far as I know you shouldn't fertilize before they bloom. But you may want to try some ironite and see if that doesn't reverse the yellowing trend. And check to make sure they aren't sitting with their feet wet. If they are, I'd buy a bag of peat, gently dig/pull them up (wide rootball! Then add peat to the whole to elevate them; replant with the roots right at the surface. Potect the roots with mulch in case you get a late cold snap.

Smiln, the quickest way to green them up is to get yourself a garden sprayer and liquid iron and spray the foliage several times over a week. This is the quick fix and should be done when the plants start growing again (you can do it now to see if it helps - it can't hurt). A bottle of liquid iron is about 3 bucks.

You might also want to go have a soil test done to determine your soil's pH (the test will also tell you what kind of and how much fertilizer should be applied). The pH for azaleas needs to be around 6 or less for best growth. If it is more than 6.5, you can add aluminum sulfate (epsom salts) and this will decrease the pH fairly quickly. I have the same problem you have and have to spread about 4 to 5 cups of aluminum sulfate around each plant in the spring and then again several times throughout the growing season.

The reason why is that our water is groundwater that is high in calcium carbonate resulting in a high pH that then raises the soil pH when I water. If you have the same type of water (you will see a white deposit when it evaporates or when you boil water), then this is going to be a never ending battle for you too if you water your azaleas. You will then need to find a source that sells aluminum sulfate by the 50 lb bag (it's < $15 where I buy it). This is the only solution that I have found.

Yes, it does sound like chlorosis or waterlogging!! Can't add anything further to the advice that's already been given!!

Hmmm. I didn't think Epsom salt was Aluminum sulfate for some reason. Magnesium sulfate maybe? If not, I have been buying both for no good reason, LOL! If they are different, 5 lbs. of Aluminum sulfate can be purchased for a few bucks at Lowe's in their fertilizer section. But I would really recommend a soil test before you start adding much of anything other than perhaps some iron to reverse the chlorosis.

And first I would really check for standing water problems - that's one of the fastest ways to kill azaleas, and one of the easiest problems to fix :)

I wish I could dig these things up, but I'd need a backhoe. These azaleas are anywhere from 3 1/2 - 6 ft tall. In fact, I have 2 that are nearly 7 ft tall. They are WELL established and I'd have a tough time getting them up. I'll have to do the soil test (just happen to have a kit on hand) and see what it reads. Duhhhh. Never thought of that. :)

I'll let you know. Thanks so much for the help.

Oh, and we have tulip trees and some azaleas blooming already, although it's still early. Poor things are confused.

Carla they sound too established too dig them up and that would be a shame!! They have obviously liked being where they are. Do the tests and amend accordingly!! Yes, it does seem very early for your azaleas to be blooming. Our tulip trees don't start to flower until well into the season!!

Our weather has been so bizarre. I'm outside in a short-sleeved t-shirt and lightweight pants today. Ummmmm, it's January. The other day, it reached a high of 79. What's up with that? The record is 81. I have forsythia blooming, azalea and my tulip tree is starting. One good freeze and it's all over.

go_vols, you're right about the magnesium sulfate. I am always mixing these two up. So smiln, use the aluminum sulfate to decrease the pH of you need to.

PH is 5.0, which is right on target. Gee, my first soil test. That was easy. Now what? My soil isn't too alkaline, so test for the other nutrients?

Chelated iron still sounds like a good bet. You can buy Ironite (granules) or it sounds like there's a liquid variety you dilute and spray on the foliage. (I always keep Ironite on hand, so I've never tried the liquid.)

Well, it's not chlorosis then if your pH is 5. The other possibility is lace bugs. Check to see if there is a lot of rust colored "stuff" on the underneath side of the leaf. If there is, then you've definately got lace bugs. They will also cause the leaves to look yellow as they suck out all the chlorophyll from the leaves leaving the rust colored stuff as excrement.

I have a recurring problem with lace bugs and treat with a systemic insecticide - the only insecticide I have had to resort to so far. Can't remember the name of it right now, but if you can confirm the rust color on the underneath side of the leaves, I'll go out and get the name of the systemic and post it.

Just thought of one other possibility - you may have them standing in water for too long which will cause the leaves to turn yellow, then turn brown, and then die. In this case, you need to dig them up and plant them so that they are 4-5 inches about the soil level and cover with dirt and a good mulch. You will have to water more frequently until they get established again, but this may solve the problem. Are these new or old plants?

Copperbaron, even though her pH is fine, does that rule out chlorosis entirely? I think I understand the basic premise - if the pH is severely alkaline, the plant cannot take up the existing iron present in the soil. But could there be a deficiency of iron in the soil, which would cause the same problem and symptoms?

Smiln, I think we're determined to make you dig up those plants yet, LOL. Or not, given their size - 7' did you say?

go_vols, I didn't reread her previous posts about what size they were, which is why I asked the new or old plants question. If they are that big and the pH hasn't all of a sudden gotten a lot higher, there is always sufficient iron in the soil where she is located - this is a micronutrient that is generally way in excess of the plants needs in the clayey soil of the south. They obviously have liked where they were for a number of years, so being waterlogged is not likely.

This leaves insect problems - lace bugs, spidermites, or scale, each of which can cause the leaves to turn yellow and look chlorotic. The dieback of the leaves is what is throwing me - another possibility is nematodes. Again, the lace bugs will leave brown excrement on the underneath sides of the leaves, the spidermites will leave very fine webbing, and leaves on which foliar nematodes feed gradually lose color, turn brown and die and soil nematodes cause problems with nutrient uptake resulting in the same symptoms.

In addition, overfertilization can cause what looks like chlorosis as this interferes with the root systems ability to take up iron. Without being able to see the plants up close and personal, the cause of the yellowing is difficult to diagnose since there are so many potential causes of the problem. Sometimes, azaleas just aren't easy to grow. Sorry smiln32 that I haven't been of much help.


This message was edited Wednesday, Jan 30th 7:44 PM