Ask a Question forum→Big leaf hydrangea dieback

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San Jose, California
weipe007
May 7, 2020 11:55 PM CST
I got three big leaf hydrangea(let's dance big easy with PW label) from Amazon two month ago. I was shocked by how small the pot and also bad condition of the plants after receiving.One is kind of okay and the other two are very tiny and the old leaf already dead(they claimed these small plants is at least 1 year old.) The worse of one looks like have some top leaves missing or rotting, but I think it maybe due to the transport and should be easy to recover.

However I was wrong, while the other two slowly grow, the last one's top leaves slowly all rotted and only leave the stem. (And now even stem wilt). I also noticed if I leave it outside during night, the morning dew seems to make it rot more. So I have to babysit it and bring it back to garage before night time.

After one week, one day I forgot to bring it to garage causing even worse rot. And feed the plant with kelp liquid and spray neem oil. And all seems not help. Not looks like the plant is almost dead. Is there still anything I can do before giving it up? Is my other two hydrangea in good condition?

San Jose(hardy zone 9) and I put them in morning 4 hours sun spot.

Thanks in advance!

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Name: Lynda Horn
Arkansas (Zone 7b)
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gardenfish
May 8, 2020 12:07 AM CST
I'm thinking you may be overwatering. And please be aware of some sellers on Amazon. I'm not saying that there aren't some good folks selling plants there, but when buying any plants on Amazon you need to be aware of the reviews and try to avoid third party vendors. Hydrangeas are shade plants, so don't give them much sun. I would it give them any more fertilizer until they recover more from the shock from transit. I don't think the humidity at night is either causing or making the root rot any worse.
Hydrangeas are garden plants and need to be planted in the ground. They are not houseplants. You will need to plant these, and this may cause further shock. Monitor watering carefully after you plant these.
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Mother Teresa
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 8, 2020 2:37 AM CST
The plants appear to be sort-of ok.

The red color in the foliage indicates that they experienced some form of late frost though. Leaf surfaces damaged by cold temps will likely turn brown and sometimes disintegrate on their own. The "worst" one of the three plants is starting to put new growth from the base. All of this indicates that the roots are in good shape.

The partial lack of foliage in the "worst" one is also normal in Spring and it suggests that temperatures were cold enough to zap the foliage of stems and-or even zap the stems themselves. If the dead looking stems fail to leaf out by the end of May, you can very lightly do a scratch test on the stems to see if you see green or not. If not, prune the stem to the ground. There is new growth coming up from the crown so that means that the roots are ok and you will have new stems. Maybe those dead looking stems will develop new leaves in 2-4 weeks.

Maintain the soil as evenly moist as you can and mulch them. Slowly transition the plants to more and more sunlight until they are planted in the ground. They typically need morning sun only (shade in the afternoons and in the evenings), dappled sun or full -but bright- shade.

When to water: insert a finger into the soil to a depth of 4" and water of the soil feels dry or almost dry.

How much to water: varies depending on soil types, etc but start with 1 gallon per plant and see if, sometime after watering, the soil feels moist down to a depth of 8". If the soil is not moist at a depth of 8" then increase the amount of water per watering. Typically, start using around 1 gallon as soon as they leaf out in Spring (more if it does not get moist down 8" deep). Then as temperatures remain above 85F most days, increase the amount of water. Then as temperatures remain above 95F most days, increase the amount of water further. Always water the soil and never water the leaves. Water early in the morning, in all directions around where the root ball is located (where all the stems are coming out of since there are no roots much further away yet). As temperatures moderate in the Fall, reverse this process. Reduce the amount of water one notch when temperatures regularly stay below 95F. Then reduce again when they stay regularly below 85F. Tweak as needed for your conditions which may require even much, much more water than those numbers. Once the plants go dormant in the Fall and the leaves brown out, you can reduce watering down to once a week or once every two weeks, depending on local rains. If winter is dry and the soil has not frozen, water like that. Resume normal Spring watering frequencies and levels once you see leaf out.

How to set a sprinkler in Spring: use the finger method mentioned earlier daily, in the early morning 6-8am, for 2-3 weeks. Water 1 gallon when the soil feels dry or almost dry. If you water, make a note in a calendar saying that you watered 1g on day xyz. After 2-3 weeks, review the notes. Average out how often you were having to water (once every 3/4/etc days for example). Then set the sprinkler or drip irrigation (or manually) to water 1 gallon of water on that frequency of days (every 3/4/etc days). If weather conditions change and temps go up/down by 10 degrees or more, use the finger method for 2-3 weeks again to see if you need to tweak things.

Did you give them enough water: remember that a single watering should reach around 8" down.

Note: if your soil is sandy, you need more gallons of water than normal, usually 50% more, and the soil needs to be mixed with 50% organic compost as sandy soil is low in and lacks some minerals. An annual layer of organic compost helps sandy soil as well as more fert applications.

If the pots already contain those round fertilizer pellets, they will not need to be fertilized now. Hydrangeas are not heavy feeders but during their first 3 years or so, I would give them 1/2 to 1 cup of cottonseed meal, organic compost or composted manure. You can also use a general purpose, slow release fertilizer that has a NPK Ratio of around 10-10-10.

To help them on windy days and hot/cold days, maintain 2-4" of organic mulch (no rocks though) year around. After they are established, they can feed off the decomposing mulch if your soil has no issues.

For the one without almost any leaves, I would just mulch and maintain the soil as evenly moist as you can. No periods of moist soil followed by dry soil, followed by wet soil, followed by dry soil, etc. This type of inconsistent watering can make it hard to bounce back. Do not fertilize it now. If it does not have fertilizer pellets then just wait until it recovers a little more, starts to leaf out, and the leaves are larger. Then you can fertilize it (if temps are not summer high by then). The last fertilizer application for hydrangeas in the ground should be at least three months before your average date of first frost (that occurs close to the middle of Dec for San Jose)..
[Last edited by luis_pr - Jul 10, 2020 2:42 PM (+)]
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San Jose, California
weipe007
May 8, 2020 2:55 PM CST
Thanks Luis and Gardenfish! Very helpful suggestions!
Actually I got these plants from a 3rd party vendor called Hirt's Garden, it seems already have some not very good comments and I didn't spend time to read... It seems buying from local shop is a much better idea.

The plants just came with a very tiny 4" pot and all seem pretty wet, I even doubt they put something into the soil to make it keep on wet. I planted them into 1 gal pot one day later after receiving them. At that time the worst one have 3 sprout stems (sorry forgot to take photos), including one stem only(it seems the top tip rotted or broke), one stem with two very tiny leaves and seem going to rot, and last one with one bigger leaf and also little sprout. After time, they all very slowly rotted and leave the stem only. Before it has some little new sprouts on the side of stems, and those seem wilt as well now after I left it in the garden every day. I am quite unsure whether it will recover and the other two seems better now after the temperature raised to 85F or higher. And the worse one seems no sign of bounce back. Should I plant the other two now into to ground?

I watered the plants every 3-4 days(maybe too often) after the top 0.5 in soil dry. Maybe that is too frequent? The worst one seems always wet around its root ball and I can see some small white debris like fertilizer or something to keep it wet. But I can not remove them because they are mixed in the origin 4" root ball soil. I am thinking continue to give the worst one more time to see what happened, should I mulch it even in pot? will the more moisture make the root rot more? (Not sure about the status of root, but looks like up the soil part most wilt)

The label of these hydrangea shows Full Sun/Part shade and zone 5-9. Is only 3-4 hours morning sun sufficient?

I am attaching more photos and the label of the plant for your reference.

Thanks a lot!




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Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 8, 2020 3:18 PM CST
Acclimate the leaves slowly to receive more and more sun first. Then plant them.

Leaf out is a very slow process that can take roses 2 weeks or less and for some reason, hydrangeas take 2-4 weeks.

Watering every 3 days when the top 1.2" of a 4" pot is dry is ok. If you move it to a 1g pot then you need to insert the finger deeper.

No need to mulch in those pots.

Yes, 3-4 hours of sun is fine. Less is also fine for macrophyllas too (they still bloom with 1-2 hrs or even less).

Root rot - the symptom is the same as lack of water since rotted roots prevent the plant leaves from getting water. You should see that leaves are wilted 24/7. Roots themselves will look rotted and may also smell. If the plant has a mix of good and bad roots, you can prune the bad ones and then hope that it can recover. Then provide evenly moist soil.
[Last edited by luis_pr - May 8, 2020 4:04 PM (+)]
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San Jose, California
weipe007
May 8, 2020 4:04 PM CST
Thanks Luis! Will following the guide and plant the healthy ones after they get used with the condition. (They are all in 1g pot now)

Does this hydrangea have shallow root or taproot? For the worst one, should I now dig it out and check or wait for another two weeks? I also notice the stem slowly dieback more and more. No recover sign in recent 1-2 weeks. But no bad smell around plant.(You can see my latest photo is even worse than previous one.And now it is in a morning sun spot which have 2-3 hours sun)
[Last edited by weipe007 - May 8, 2020 4:05 PM (+)]
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Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
luis_pr
May 8, 2020 4:10 PM CST
No tap roots per se. Just a mess of tiny fibrous roots in the top 4" of the soil.

I would wait to see if it is in the process of leafing out again. If it does not leaf out in 2-4 weeks then consider extracting to check the roots. Just be careful as they probably do not like it when we do that.

It would be just fine if the stem dies. That would not kill the roots. Since the plant already has new growth -meaning new stems- that means the new stems will grow and take the place of the ones that died.
San Jose, California
weipe007
May 8, 2020 4:48 PM CST
Thanks Luis!
Will keep monitor it for another month and keep you updated! Looks like the weather become warmer nowadays which may help the plant to sprout.

Have a good weekend!

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