Ask a Question forum: Brown spots on my hydrangea stems PLUS yellowish leaves AND dry flowers :(.

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Santiago, Chile.
Jan 19, 2018 4:16 PM CST
Hi guys! I'm new to the site because I need help! I have some flowers on my balcony, they are going well. I live in Santiago (Chile) and it's summer time here (more than 30 ºC / 86ºF).
Some weeks ago, on december 21st to be exactly I bought a pink and purple Hydrangea, I wanted blue but they didn't have and I have read that is pretty easy to make them change the color, just adding some rusty nails, I didn't have rusty nails just new nails but I added it anyway. 3 small one. The plant started to dry out so I took them out but i continued drying. It has a lot of brown spots on the stems BUT i noticed in some pictures I took the day I bought it they were in there since the beggining. And the leafs are yellowish, can you help me find out what kind of problem is affecting them?
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Name: Christine
Saugerties, NY zone 5a
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Jan 20, 2018 7:39 AM CST
How often do you water? The one I have in a container gets watered every day, some times twice a day when its really hot. What kind of potting soil are you using? Personally I would not be putting rusty nails in my plants, other members will have more advice for you Thumbs up

Welcome! To The Forum
Santiago, Chile.
Jan 20, 2018 7:43 AM CST
Christine said:How often do you water? The one I have in a container gets watered every day, some times twice a day when its really hot. What kind of potting soil are you using? Personally I would not be putting rusty nails in my plants, other members will have more advice for you Thumbs up

Welcome! To The Forum

Since it's so hot in here I water them everyday too.
The soil is... I'm not sure special soil for pots.
I put new nails in the plant but I took it a couple of days after.
Hurst, TX (Zone 8a)
Dog Lover Region: Texas
Jan 24, 2018 1:28 PM CST
Hello, Divshahf. From looking at the first picture, your home is not at ground level but is rather several stories high. This probably means that your balcony is exposed to light (or strong?) drying winds, especially in the afternoons. This can make the potting soil dry out slowly/quickly so try to keep the soil as evenly moist as you can. This may even require watering multiple times a day if the soil is dry. You can test the soil by inserting a finger into the potting soil to see if it feels dry, moist or wet. If the potting soil is dry then water it but otherwise do not water if moist/wet. Hydrangeas prefer soil that is typically evenly moist, meaning that the soil does not go through period of dry soil, followed by wet/moist after you water, followed by dry and so forth. These cycles can cause some leaves to brown out at the edges and if it is dry enough, the leaves will brown out from the edges inwards until they fully brown out or the soil is moist again. Of course, once brown, the leaf or that section of the leaf cannot recover and turn green again. If it is aesthetically bad looking and just a few brown leaves, you could cut the leaves at the petiole (the string that connects the leaf to the stem).

Brown Spots:

Hydrangea leaves suffer from several issues. You have one of the most common ones, called leaf spot. Cercospora leaf spot is a fungal infection that sometimes looks very bad, can defoliate some plants in extreme infestations but, leaf spot would rarely kill the plant. It, however, suggests that the leaves are getting wet. I would suggest watering early in the mornings only and never watering the leaves, only the potting soil. When I purchased my current home, it came with hydrangeas and they suffered from leaf spot. The fungal spores are out there in the environment and they caught it when the sprinkler watered them in the daytime hours.

To minimize the leaf spot, when my sprinkler system died, I switched to drip irrigation. This minimizes the condition but it usually pops in wet years and by the end of the growing season ("summer" for you). You can do this too, sort of. Just water the soil. This infestation is easy to control if you do not do overhead watering and dispose of fallen leaves where the fungal spores reside. The spores accumulate in fallen leaves, stems and blooms as well as in any other plant debris sitting on the potting soil.

In plants with leaf spot, I would only water the soil, keep the potting soil "clean" of plant debris (mulch is ok but I would replace it with some regularity as it too can harbor spores) and throw in the trash fallen leaves/stems/flowers. Cercospora leaf spot is usually in the leaves all the time but, in the Spring, it is not visible….because the leaves are producing a ton of chlorophyll, which hides the spots unless you look very, very up close. However, in the summer, chlorophyll production is reduced and you "see" the spots. Cercospora cannot be cured. There are some expensive fungicides for sale down here (to help control it, not cure it) but, they are probably not worth using this late in your growing season. Besides, you have a light infestation, just a few plants and after all, the plants should drop leaves soon when winter arrives for you. The plant will then leaf out in the Spring and show new leaves but remember, the spores are already inside the plant so you will always get some of these spot by the end of your growing seasons (summers).

Yellow leaves:

Some of the yellow leaves that I saw in pictures #2 and #7 look like summer leaves that hydrangeas can drop due to heat stress. They look all yellow, including the leaves' veins. It usually involves a few leaves and nothing more. If you notice a lot more (there were few yellow ones in the other pics so I assume it is not too many), post again. Another possibility for yellow leaves that I could not confirm from the pictures is too much sunshine. Hydrangea leaves are very sensitive to sunlight, especially mopheads and lacecaps (H. macrophylla –what you probably have- or H. serratas). If the plants get too much sunshine, the leaves in direct contact with the sun can turn all yellow-ish (or white-ish) -including the leaf veins- but the other leaves protected from the sun remain dark green. If you observe the inside leaves being dark green and the others yellowing then the plants may need more shade. Hydrangeas are typically understory plants in the wild so when we grow them in homes, they will do best in morning sun and afternoon shade. Another possibility for yellow leaves is a condition called iron chlorosis, which I could not find in the pictures. This one is easy to tell as the leaves turn yellow EXCEPT for the leaf veins which remain dark green.

Potted hydrangeas tend to have this iron chlorosis issue because the minerals in the potting soil leech thru the pot's holes at the bottom of the pots when you water. And potted plants require more frequent waterings, which does not help. Rusty nails or iron shavings do not correct iron deficiency.

Basically, you have two things due to losing minerals: aluminum is being leeched out; iron gets combined with other minerals and cannot be absorbed by the hydrangea roots. The first prevents blue blooms. The second, if you allow the soil to get more alkaline, can cause iron chlorosis on the leaves. The fact that your blooms are not blue but pink/purple suggests that the soil pH in the potting soil is or is becoming alkaline but not too much yet. And it suggests the plant is not getting enough aluminum. But again, it is not "a problem" yet because the leaves do not display yellow leaves with dark green veins. To correct these things here (fyi: my soil and my water is naturally alkaline), I amend the soil in Spring and -sometimes- again in the Fall.

You can deal with this condition by adding soil amendments that add garden sulfur and aluminum. Re-apply it per the product label in order to produce blue blooms. Very carefully increase the levels of the product to acidify the soil. Some examples of these products are greensand, iron-chelated liquid compounds, aluminum sulfate, etc. You can typically find these products in plant nurseries here in the US, especially those that sell lots of hydrangeas. Some people add vinegar to the water when they are watering too. Be aware that fixing the yellowing with dark green veins is a slow process… that is, takes many weeks.

To get blue flowers, you need to acidify the soil much more and be careful not to over do the soil amendments so the hydrangea roots will not get "burned" if you use too much of the soil acidifying amendments. The applications need to continue forever as the minerals you add eventually get leeched out. I use aluminum sulfate for this blueing. You can correct iron chlorosis by adding garden sulfur alone but you will need to add aluminum to get blues too.

Dry flowers:

Your hydrangea flowers look normal. At the end of the growing season, the colors change/fade and you get green and pink spots on the sepals. At the end of Summer or the start of Fall, blooms should turn pink-ish. May also look/feel paper-ish (some people cut them at this stage to keep dried blooms and use them for decoration). Or they leave them on for winter interest. Or the cut the string that connects the bloom to the stems.

Hydrangea flowers develop from flower buds that the plants create in midsummer. These flower buds are originally invisible and are "hidden" near the ends of the hydrangea stems themselves. In my area, this occurs in July; it may occur around Jan-Feb in Chile. I mention this so you do not cut the hydrangea stems now when removing the old and spent blooms. Cut the string that connects the bloom to the stem instead. Because hydrangeas are deciduous, they look like dry sticks during winter but the stems are alive and contain flower buds and leaf buds that you cannot see until Spring arrives and these open.


Some varieties of hydrangeas have stems that display some dark spots. It is normal. The stems also harden for winter and change color.

Does this help you?
[Last edited by luis_pr - Apr 27, 2018 6:22 AM (+)]
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Hurst, TX (Zone 8a)
Dog Lover Region: Texas
Jun 29, 2018 6:19 AM CST
From afar, I was going to say that they resemble some scale that was attacking my Crape Myrtles some years ago but, when I try to look sometimes, I get the feeling that I am seeing webbing. That usually means one has spider mites. It is also conceivable one has both pests too. If someone with telescopic vision does not show up, get a few of the critters in a sealed plastic bag and take it to a local plant nursery for analyis. A local university with an Agric Dept and similar programs could also help.

Jun 29, 2018 8:26 AM CST
Good morning Luis,

Thank you for the advise. I'll visit the nursery this weekend. If that the case do you suggest that I should cut all the stems with that dark brown looking insect out and repot again? Do I have to do anything to make sure that it doesn't occur again?
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Hurst, TX (Zone 8a)
Dog Lover Region: Texas
Jun 29, 2018 9:20 AM CST
No, no need to do that to he stems. You can usually spray insecticidal oils or soaps for some of these pests. Or spray with a hose for mites (hard spray) too. The hose spray yanks them off the leaves and kills them as they bite and hold on to the leaf that way... until the hard hose spray separates them from the leaf. Or use neem oil or miticides. Google control for these pests (scale, mites, etc) and you will get many suggestions on how to deal with these pests.
[Last edited by luis_pr - Jun 29, 2018 8:28 PM (+)]
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Jun 29, 2018 6:11 PM CST
Hi Luis,

Thank you so much for all the helps. I am looking forward to go and get insecticidal oil or soap this weekend.

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