yellow leaves

[ktknek]

My hydrangea has looked like this for weeks. It stared to grow back in spring. Then stopped getting any bigger. Some of the leaves are somewhat yellow and i don't know why. It seems healthy otherwise. What could be causing this?

[luis_pr]

Your soil is too alkaline. While hydrangeas prefer acidic soils, they tolerate some alkalinity. But if the soil is too alkaline, they reach a point where they no longer can absorb naturally occurring iron from the soil. And when that happens, they develop a condition called iron chlorosis. The symptoms are: leaves whose color turns light green or yellow, except for the leaf veins which remain dark green. Growth is stunted.

Controls: as soon as you notice this condition developing, amend the soil using any one of these according to label directions: garden Sulphur (such as Espoma's Soil Acidifier 5lb bag for $7-9), green sand, iron sulfate, aluminum sulfate (but keep it away from azaleas and rhododendrons) or iron-chelated soil acidifier liquids such as Green Light's Iron & Soil Acidifier (can't remember but slightly more than $8 for a 32Fluid Oz bottle). You will need to make several applications of whichever one you choose, until the leaves turn back to normal. Most plant nurseries will have one or more of these products; they are widely available. Liquid compounds will correct the problem faster though.

If you remember when this problem first became obvious, it would be a good idea to amend the soil a month before that every year. I suggest making a note on a wall calendar indicating that you have to amend the soil. Then pass along this information into new calendars in January.

This condition can also quickly develop when it rains a lot but it self corrects in a few weeks. I would still amend the soil at such a time again. Here in Texas, I try to amend the soil every Spring and again as needed (sometimes again in either July or August).

Azaleas and rhododendrons suffer from iron chlorosis in alkaline soils too. Their problem can be corrected using any of those products, except for aluminum sulfate because a/s is toxic to azaleas and rhododendrons in large enough quantities. Roses and Camellias also suffer from iron chlorosis in alkaline soils.

Plant nurseries sell all kinds of soil pH kits to measure the acidity and alkalinity of the soil. If you can find one that you like, use it every Spring and 1-2 more times annually to check how the soil is doing. If the soil kit gives you results using soil pH units, aim for getting it to a reading near 7.0 (neutral). A change up/down 1 point means that your soil 100 times more/less acidic than it used to be.

Luis

[ktknek]

Thank you for the help my plant is starting to look better. This was my first time buying numbered fertilizer. Maybe it was the wrong kind.

[Purplehaze13]

I thought I would bump this thread as I am having a similar problem, but I'm not sure if it is the same thing. I'm getting yellow leaves on some of my plants, but they don't have the dark green veins as described above, so I'm not sure if it's the same problem. Here are some pictures:



Is this something different or should I try the above solution? Thanks for your help.

[luis_pr]

Happy Memorial Day Weekend, Purplehaze13. Make sure you are not watering too much as it can sometimes trigger yellow leaves. Also dp not water the leaves or apply too much fertilizer.

Watering too much prevents the leaves from getting oxygen thru the roots and causing wilting and eventually a fungal infection called root rot.

Hydrangea leaves do not benefit from direct watering. Once in a while is fine but more often and they will develop leaf spots, a fungal infection like the one seen in the two photos. Instead, water the soil about 1 gallon of water very early in the mornings.

If you add too much nitrogen to the soil, leaves can turn all yellow like the ones in the 2nd photo. A single fertilizer application in June or two (in April and July) is all they need.

I would cut off the affected leaves since they appear to be few and the plant will not need them. But throw them in the trash, not a compost pile, due to the possibility of some fungus already being on the leaves. Luis

[Purplehaze13]

Happy Memorial Day weekend, Luis! Thank you for the quick reply and help. I actually haven't even begun regular watering yet this year, but we have been getting a lot of rain in Southeastern Virginia the past 2 weeks. Out of the past 12 days, I think it's rained 6 or more days, often all day. I also haven't added any fertilizers.

Right now I am just using a pine needle bedding, but some of the plants have English Ivy around the bases (NOT planted by me!) that I am trying to get out of there. Could the Ivy be affecting them at all?

I will go ahead and trim off the yellow leaves and keep an eye on them. Thanks again for your help.

[Purplehaze13]

Update: I was just out trimming off the yellow leaves, and noticed a white, powdery substance around the bases of a few of the plants. Not all the plants that had yellow leaves had this, though. Is this the fungus you mentioned, or something else I should worry about?

[cynthia_h]

Without a photo to show the proximity of the ivy and the hydrangeas, I'm going to make a Big Assumption that the ivy is impeding air circulation at the bottom of the hydrangea plants.

English Ivy is a scourge, a nuisance, a...well...responsible gardeners don't want it growing anywhere near their valued plants! Do what you can to remove it from the hydrangeas, including pulling the ivy out by the roots. Right after rain is a good time to uproot ivy: the ground is soft, and the roots will come out more easily than at other times.

Just try to avoid harm to the hydrangeas.

Best wishes.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[Purplehaze13]

Thank you cynthia_h, I think you may be right. I have been trying to get the ivy out for awhile, and am making some progress. I will remember the tip about getting to it after rain! I hate the stuff, and I get so mad when I see people plant it on purpose!!

[luis_pr]

I inherited one around the mailbox and it has remained there by itself. But I am curious, what was that tip about "getting to it after a rain"???

[Purplehaze13]

I inherited one around the mailbox and it has remained there by itself. But I am curious, what was that tip about "getting to it after a rain"???

Oh, cynthia_h had said that ivy is easiest to pull up after a rain, when the ground is still a little wet.

[luis_pr]

So true. And especially here in clay land. Once we begin hitting the hundreds daily by mid June, it is very bad trying to pull even weeds out of the ground. By then, I coordinate extracting plants from the ground with my sprinkler's schedule. Hee hee hee! Better yet, wait until September.