Ask a Question forum→Incredible Hydrangea wilting and dying

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Bellevue, WA
tanyatobin2021
Jun 17, 2021 6:56 PM CST
Hi ,

I live in Bellevue Washington. I have these incredible hydrangea for more than 5 years. Every fall I would prune these bushes and leave only a foot above the ground. Last fall I decided to leave about 3 foot above the ground after reading that the strong stem would help support the huge flowers.

In the early spring this year, all things went well. They even generated more flower bud this year. Now we are almost reaching summer, I started notice that couple bushes stem start to wilting. After over night, those stems did not come back from wilting die from the stem eventually. But some of the stem did come back over night. I tried more water, but they did not help, they just start to wilt as soon as sun shine on them. I also noticed that the leaves turning yellow and new sprouted stem started to die out. I know the soil is moist, maybe even too much that could root to rot? I really want to save my incredible hydrangea. Any help or idea would be really appreciated.

Tanya





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Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
Jun 17, 2021 10:11 PM CST
Welcome to NGA, Tanya. While the wilting episodes may look dire, the plant does not appear to be dieing in the pictures. But you m-a-y be watering too much, especially if your watering is reacting to wilting episodes of the leaves. It is very normal for hydrangea leaves to wilt when the plant is stressed. Hydrangea leaves wilt because the leaves lose moisture faster than the roots can replace it by absorbing more water. Scenarios that can cause wilting of leaves: too much sunlight, lack of water, root problems, high temperatures, windy conditions, newly planted or transplanted, low humidity, pests, etc. What is more, Smooth Hydrangeas like Incredibelle are more sensitive to heat stress so let's go over the basics:

Sunlight - make sure that the plants receive direct sunlight until 10-11am. If they are getting afternoon or evening sun (any time after 10-11am), evaluate if it is too sunny now and if you need to provide temporary shade so you can transplant them when temperatures recede during the Fall.

Watering/wilting issues - Aim to provide acidic, well draining soil that is as evenly moist a possible. Avoid insufficient watering, excessive watering and inconsistent watering that results in periods of dry soil, wet soil, dry soil again and so forth. Use the finger methods to help:

To know if they need water, insert a finger into the soil to a depth of 4". That is the typical depth of most hydrangea roots. If the soil feels dry or almost dry, water the plant. If the soil feels moist or soggy, do not water.

To know if you watered enough, water when it is appropriate, wait for the soil to drain the water and then check the soil at a depth of 8": insert a finger to a depth of 8" in several spots around the plant this time and see if the soil feels dry, most or soggy. If the soil feels dry, either you missed a spot or consider if you did not use enough water.

To see if the soil is too soggy (or if you are using too much water), test the soil at a depth of 4-8": insert two fingers to a depth of 4-8" in order to extract some soil (1/4" to 1/2") in between the two fingers; press on the soil and see if you observe water droplets forming. If you do, the soil currently has too much water either because the soil was recently watered or it rained, the soil does not drain fast enough or you are watering too often, too much or both. Too much water prevents the roots from absorbing oxygen and that can result in foliage problems. If the excess amount of water persists for a long enough time, root rot fungal infections can develop.

Checking the roots for root rot and using these finger methods can help answer your question "is the soil so moist that the roots rotted?". Your shrub does not appear to be on its last legs yet but you need to determine if the soil is too moist and use the finger methods to control your waterings.

It is important that you do not make a habit of watering just because you see wilting because the roots may then develop root rot. Wilting occurs when the internal pressure drops and it can be considered a self defense mechanism because the amount of leaf surface being hit by direct sunlight gets reduced by wilting and that helps reduce moisture loss by the leaves. While you should increase the amount of water if weather conditions change closer to the summer, try not to overdo it. Soil that drains very well (think: sandy soils, etc.) can probably withstand extra amounts of water or watering twice a day but be careful otherwise. See the above comments on the finger method so you know when to water, how much to water and how to tell if you watered too much.

Just like leaves wilt, hydrangea stems can also wilt. Old stems however, tend to be woody and new stems or new parts or old stems tend to be green. The green parts may wilt if the plant loses moisture through the leaves too fast, does not have enough water in the soil or has root issues that prevent it from absorbing as much water as before. For example, there are underground pests that may damage (eat) the roots like voles.

Watering requires that you -for example- water only the soil and do it early in the mornings (7-8am) starting from the crown (that is the area where all the stems originate from) outwards. Water the soil in a circle so the water will reach the roots that, after 5 years, are now growing in all directions. Since some of the plants are large and getting a bit wider, it is possible that some roots are not getting enough water because there is now a large number of stems that can block the water from a sprinkler head (Picture #2). Drip irrigation also requires tweaking now and then when the plant grows wider or if the tubing is only watering one side of the plant only (say, the front).

Plastic or landscape fabric, as well as rocks used as mulch, are not always recommended. The fabric disrupts movement of nutrients, air, and water into the soil. The rock mulch absorbs heat during the day and releases heat at night, just when hydrangea roots want a respite from the hot day but will not get it. Some types of rocks also leach lime; rocks as mulch work when the root system is large, when the weather is not terribly hot and when the rocks are not leaching lime.

How to set your sprinkler or drip irrigation system: use the finger method for 2-3 every morning (7-8am) like so - insert a finger into the soil to a depth of 4" and see if the soil feels dry, moist or soggy; if the soil is dry then water and make a note in a wall calendar or an electronic calendar indicating how many gallons of water per plant you gave them on that day; after 2-3 weeks, review the notes and determine -on average- how often you had to water and -on average- how many gallons you were using per plant. So for example, you may find that you used 1 gallon of water per plant every three days (just an example). Then in that example, set the sprinkler or drip irrigation to provide 1 gallon per station and make the system run every 3 days. If your weather changes (gets hotter/colder by 10 degrees up or down, for example) then feel free to use the finger method again for 2-3 weeks to see if you need to tweak things.

High temperatures - hydrangeas will typically get heat stress when temperatures typically reach or exceed 85°F. In Belleveue, that starts at the end of June or thereabouts. Once this happens a lot, it is time to switch the amount of water from "Spring levels" to "Summer Levels".

High winds - the flow of slow and high winds by the leaves can promote leaf moisture loss even if temperatures are well under the 85°F mark. As a result, I consider watering on the night before wind advisories are issued by the National Weather Service.

New or transplanted hydrangeas will have their root system disturbed when you plant or transplant. Their roots are just 4" deep so they can be easily disturbed. That can make the uptake of water more difficult. New plants do not necessarily have a large enough root system so one plant may struggle in the summer more than the next one even though they have similar dimensions.

Foliage - it is common for Smooth Hydrangeas to yellow out some leaves due to low humidity and heat stress during the summer months. New growth can also fail if the soil is too soggy or has damage from late frosts earlier in the yea (overnight lows in Bellevue got very "frosty" on April 11: 35°F).

Too much sun - there are various degrees of "too much" sun. A little too much sun can help the leaves lose moisture. Truly too much sun will cause the leaves in direct contact with sunlight to turn all yellow, including the leaf veins, while the shaded leaves remain green. Truly too much sun can also brown out the white mophead blooms early.
[Last edited by luis_pr - Jun 18, 2021 3:32 AM (+)]
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Bellevue, WA
tanyatobin2021
Jun 18, 2021 12:35 PM CST
Thank you so much for your reply.

I was struggling to save these incredible hydrangea. And have researched info online. I knew I have probably over watered them and caused the problems I overserved now. I am hoping it is not some kind of diease that eventually cause the plant to die.

This morning, it was about 65 F outside in the garden. Some of the stems did come back from wilting but some did not. I trimmed out those did not come back overnight. I took more pictures and trying to identify the root cause of the problem. I noticed some leaves did curl up like being burn without discoloring (but not a ton). Some leaves has brown spots (but not a ton). I did more research on the web and find one potential cause (Anthracnose), but not 100% sure. I think I need some opinion before I apply any rescue chemical that might make things worse.

Would you please help me identify if these hydrangea has Anthracnose? Is the chemical in the picture the right approach to this problem? pictures attached.
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Name: Tiffany purpleinopp
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purpleinopp
Jun 18, 2021 1:10 PM CST
Check Hydrangeas for wilt in the morning. They often wilt in the afternoon if they can't take up water as fast as it is lost, but regain their stance overnight. If that happens, they don't need additional watering.

Thinning the puny stems from the middle, and excess inner foliage and damaged-looking foliage, would allow more airflow. Water the soil, not the plant.
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Bellevue, WA
tanyatobin2021
Jun 18, 2021 2:03 PM CST
Thank you for your tips. I will trim those inner / damaged foliage. I just hope the plant will stop the deterioration and dyeing before they are fully broom.

Tanya
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
Jun 18, 2021 2:21 PM CST
Pictures 1, 4, 7: could be chemical damage or an indication of Hydrangea Leaftier or Leafcutter insects/larvae (some are green larvae with a black dot on the head; may temporarily hide under leaves or elsewhere during the day; will roll the leaf to protect from insecticides and then feed). Very common on hydrangea arborescens from May-June. It will not kill the plant but may stunt growth if allowed to increase in numbers. Most people pick them up and squish them, although I admit that doing that has an Eeck! Factor of 100 in my scale. :o))

Pictures 2, 3: I am not quite sure what this is because it was not close enough. It could be an opportunistic fungal infection too. It does not quite show all the hallmarks of Anthracnose (or maybe not yet) but if the symptoms looked like it to you, consider getting a few healthy cuttings now in case it is Anthracnose and explodes/kills the plant. You can use one of many active ingredients to treat it. Note there are insect pests that produce a clear honeydew excrement that turn leaf surfaces black/dark.

So, how about just cutting off similarly infected foliage and throwing it in the trash, not on a compost pile? Anthracnose is a disease that occurs when the weather is hot and wet and stops (but does not go away) as things get dry or too hot. Avoid watering the leaves if possible (water close to 6-8am if you use a sprinkler). If watering by hand, always water the soil. Pick up all plant debris, including dead stems and dried out blooms and flowers in the Fall (disinfect pruning shears with 70-100% isopropyl alcohol or ethanol or dunk them for 30 minutes in a solution of 1 gallon water + 2 cups chlorine bleach.

Picture 6: there are several fungicides recommended for anthracnose and that is one of them. I have seen recommended active ingredients from neem oil to Azoxystrobin, Chlorothalonil, Polyoxin-D , Pyraclostrobin, Tebuconazole and Triadimefon.
[Last edited by luis_pr - Jun 18, 2021 2:31 PM (+)]
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Bellevue, WA
tanyatobin2021
Jun 18, 2021 2:47 PM CST
Thank you for your info again.

I think I will try to cut those damage foliage and pick up drop dead branches for now. Wait a week to see how things turn out. If the problem persisted, I will give the chemical a try to see if it stop deterioration.

I will post information as I learn more. The hard lessons learned here is not to put too much fertilizer and water.

Tanya

Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
Jun 18, 2021 4:07 PM CST
Hydrangeas are not hungry plants like roses are so you can quit fertilizing once they become established, provided you do not have nutrient deficiencies like with sandy soils: they will feed off the 2-4" of decomposing mulch.
Bellevue, WA
tanyatobin2021
Jun 18, 2021 6:32 PM CST
This is such a great tips!

I have all kind of hydrangea around my house and every early spring I would dump some slow release fertilizer around them. If they are such self sufficient plant, it would save me a lot of work every year.

I really appreciated that you took time to give me such detail information about hydrangea.

I have planted these incredible hydrangeas behind a row of English Laurels. And these hydrangea are right in front of My cement porch. So the hydrangea only have about 3 foot of growing space. I am guessing that over the years, as the English Laurels and hydrangea gets bigger, their root system underground also get bigger. Plus the area is not well drained. The environment for these hydrangea is not ideal but they have broom ok for me to enjoy.

I am planning to dig them out next year and trim the root in case they got so root bound and creating problems in the long run. What do you think about this approach?

Tanya
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
Jun 18, 2021 9:13 PM CST
Feel free to dig them out if you want but I do not think it is necessary. Do so in the winter months when the plants are dormant and while the ground is workable. Remember that their roots extend outwards and are only down about 4" deep. Trimming the roots -specially rotted ones- and transplanting back on the same spot is something that disturbs the roots; it may affect some dead stems/foliage in Spring and-or maybe affect (reduce) bloomage but probably just for a year.

When hydrangeas or other plants become root bound, the plants lose vigor, may look underdeveloped and display symptoms of a lack of water often. Those are not signs being displayed in the pictures.

I am not sure if there will be an issue with English Laurel (EL) roots versus the hydrangeas roots. The EL roots tend to extend downward, as deep as 3 to 4 feet. Hydrangeas have shallow, tiny, fibrous roots mostly in the top 4" that extend out. So unless they are sharing space in a pot, they would not tend to disturb each other much.

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