Hydrangeas forum→Help with my Hydrangeas please!

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May 4, 2020 9:59 AM CST
Hi All, recently joined this forum. I am a novice gardener and need help with my Hydrangeas. For context, I live in Atlanta, GA. I planted my Hydrangeas about 3 weeks ago. The soil consists of heavy red clay so after I dug up the hole I added fresh soil before putting the plant in. The area where the plants are get about 7-8 hours of full sun. I have been watering daily either in the mornings or late afternoon. I've tried sprinkling some fresh coffee grounds since I read that this plant loves acidic fertilizers and haven't noticed any improvements.

What is the reason the plants are browning? Do I need to do something differently?
I need help and all tips are highly appreciated!

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Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
May 4, 2020 1:07 PM CST
Newly planted hydrangeas -soecially mopheads like yours- tend to be sensitive to heat stress when temperatures are 85F or higher. The leaves wilt but they perk up at night once cooler temperatures arrive and provided the soil is moist enough so try to keep the soil as evenly moist as you can. That means no periods of dry soil, followed by wet soil, followed by wet soil.

In this case, the plant has been planted in too much sun. Mopheads need to get morning sun only and shade in the afternoons & evenings. More so in the summer. So look for a spot where you can estimate that they will get shade starting around 10-11am during the summer months, for example. That is what I looked for when I lived in Atlanta. In the extreme northeast, where the sun is weaker, maybe you can plant them in full sun but not down in the South.

You are also watering too often (twice a day) although I am not sure how much you were watering. The blooms and the leaves need more shade but water is not needed unless the soil feels dry to the touch. Ironically, watch out for overwatering as that can lead to root rot if the conditions persist for too long. It is ok for the soil to be wet or soggy after you water or if it has rained a lot but not otherwise. So, try these hints:

* when to water: insert a finger into the soil to a depth of 4" (say, between 6-8am) every day for 2-3 weeks. If it feels dry or almost dry then water. Use the finger method to control overwatering. Every time that you water, make a note in a wall calendar or an electronic calendar. Indicate in your notes what day you watered and how much ( 1 gallon, 1.5 gallons, et,). After the 2-3 weeks, review the information on the calendar and average out how often you were watering. For example, you may find you were watering 1 gallon every 3 days, or every 4 days, etc. Then set the sprinkler, drip irrigation or manually water 1 gallon every 3 days, etc. To compensate for temperature changes: use the finger method again for 2-3 weeks if temperatures regularly stay 10 degrees higher or lower. Tweak things if needed.

* how much to water: a newly planted mophead can get from 1 to 1.5 gallons of water in Spring depending on soil type, etc. . After you water (say, 1 gallon), see if the soil is moist about 8" deep. If not, water more. Tweak as needed for your conditions which may require even much, much more water than those numbers.

* water only the soil and never the leaves to minimize getting powdery mildew or cercospora leaf spots. Try watering around 6-8am in the morning, in a circle around the plant's brown of stems. Water from where the root ball is outwards.

* in Spring, you typically would water around 1 to 1.5 gallons -approximately- because of its mild temperatures. Once temperatures regularly stay above 85F most days, you need to increase the amount of water. May is when that happens although very hot single days or very windy days can cause wilting. As temperatures regularly stay above 95F, consider increasing the amount of water again. Then reverse course as cooler weather arrives. Reduce the amount of water one notch when temperatures regularly stay below 95F. Then reduce again when they are regularly below 85F. Tweak as needed for your conditions which may require even much, much more water than those numbers. Once the plant goes dormant, you can reduce watering to around 1g once a week or every two weeks, depending on local rains. Since your soil does not freeze, you do not have to stop completely watering but be mindful of dry winters; you may have to water provided temps are above freezing. Then resume Spring watering amounts (1 gallon or so) when you see leaf out.

* protect the plant from late frosts by winter protecting, covering with something, whatever works for you. The plant will produce invisible flower buds in late Summer or early autumn (July-ish for me) and then these will open in Spring 2021 and resemble small broccoli heads.

* if the plant is wilted, it will be fine and perk up on its own when night arrives as long as the soil is moist enough. You can use the finger method to see if it is moist enough. Should it remain wilted in the morning, the soil was not moist enough and it needs to be watered. If you observe an extreme wilting episode, water 1 gallon immediately. Hydrangeas wilt when the leaves loose moisture faster through those big leaves faster than the leaves can absorb more water. As the plant gets established and develops a larger root system (anywhere from 1-3 years), it will have less of these wilting episodes. But you can usually expect to see them happen as temperatures get hotter, when it is windy, when a single hot days squeezes by, etc.

* feel free to water ahead of schedule (the night before) -ck with the finger method unsure- especially if the weather report calls for windy days or a very hot day (and then lower temps resume).

* if the leaves brown out from the edges inwards, that indicates that the plant is not getting enough water (but it can also be due to root rot).

* if the leaves in direct contact with sun start to turn light green or yellowish (and the other leaves stay dark green), that means that the plant is getting too much sun. But that should not be an issue if the plants gets morning sun only.

If you just bought the plant recently, it probably still has those round fertilizer pellets and will not need more fertilzing until Spring 2021. Depending on its size then, you can feed it 1/2 to 1 cup of cottonseed meal (an organic fertilizer that they like), organic compost or composted manure. You can also use a general purpose, slow release chemical fertilizer with an NPK Ratio of around 10-10-10 or so. One application a year, say when they leaf out, should be enough. After it becomes established in about 3 years say, it can just feed off the decomposing mulch. Three months before your average date of first frost (usually November for Atlanta) is the last time in the growing season that you should consider putting any form of fertilizer. Coffee grounds do not acidify the soil much but they contain nitrogen so consider that a fertilizer application. Similarly, do not apply ferts until after the plant has leafed out and your average date of last frost (mid to late April).

Provide 2-4 inches of mulch year around to help maintain the soil moist and protect the roots from temperature changes.

Does that help you? Luis
[Last edited by luis_pr - Jul 10, 2020 2:46 PM (+)]
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May 4, 2020 1:29 PM CST
Thank you Luis for this information! Sorry if I wasn't clear, I only have been watering once per day, either in the morning or late afternoon.

If I leave the plants where they are now, are they doomed since they receive too much sun? I picked that area because it is the front yard and thought it would look nice.

Should I consider buying a different type of Hydrangea that tolerates full sun?

Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
May 4, 2020 1:45 PM CST
Ah, ok, that is still too much water but whew, probably still acceptable for short periods of time. Just do not forget that your clay soil (and mine) do not drain well and require some organic compost to compensate. Otherwise, the roots stay wet for too long and that can be bad. If the finger method says the soil feels moist, do not water.

In the wild, hydrangeas are understory plants. But the hydrangea paniculatas are the most sun tolerant ones and can handle full sun in many areas. Apparently, that does not work well here in Dallas/Fort Worth as the leaves always end the season in poor shape and they tend to start blooming as my summer temps reach for the 100F every day. See how they do for you in Atlanta. The specimens for sale when I was in Atlanta were the huge varieties so that did not interest me. Check their sizes when shopping as some get quite tall but new varieties get 3-5' tall only. You can look around your neighborhood and see if you see their summer panicle-shaped blooms and see where those specimens are planted. Maybe stop by the Atlanta Botanical Gardens in Piedmont Park and see if they have any paniculatas and how much sun they get? Note: the oakleaf hydrangeas have different leaves (oak shaped) and they also have panicle shaped blooms so do not confuse oakleaf hydrangeas with paniculatas from afar.
[Last edited by luis_pr - May 5, 2020 7:03 AM (+)]
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May 5, 2020 6:44 AM CST
Are there other Hydrangea types that thrive in full sun?
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
May 5, 2020 7:00 AM CST
Only those paniculatas. Check out Bobo, Little Quickfire, Little Lime and Strawberry Sundae.
[Last edited by luis_pr - May 5, 2020 7:04 AM (+)]
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May 5, 2020 11:14 AM CST
luis_pr said:Only those paniculatas. Check out Bobo, Little Quickfire, Little Lime and Strawberry Sundae.

Luis I appreciate all the information you are giving me and I hope you don't mind all my questions!
The Strawberry Sundae Hydrangea, do you think it will thrive and not wilt in full sun (7-8 hours)? Considering I live in Atlanta, is about to get really hot here!
Name: Luis
Hurst, TX, U.S.A. (Zone 8a)
Dog Lover Region: Texas Salvias Roses Hibiscus Plumerias
May 5, 2020 12:46 PM CST
I do not know for sure. Paniculatas have somewhat smaller leaves than macrophyllas so they tend to need a little less water and wilt less. But that does not mean that they are immune. If it gets hot enough or windy enough, they may wilt. Wilting happens when the loose moisture faster than the roots can absorb it. So windy days, high temperatures and a lack of soil moisture promote wilting. That happens easily with macrophyllas but not paniculatas.

When I lived in Atlanta, paniculatas were something that was mostly sold for the northeast and very cold states only. Over here in Texas, I observe that (1) the leaves suffer and look like they had a rough time when Fall arrives in the middle or end of September and (2) the blooms start to open in the Summer when we are about to start getting into daily 100-degree temperatures. Awful timing. Vanilla Strawberry specimens in here started blooming white and went directly to brown as a result. One time I saw them turning pink ish but the bloom turned brown in a week or two, can't remember. Perhaps if one let's them grow for several years, they may get used to this but, they originated from Gorron, a town in Mayenne, France. That is in the NW corner of the country; close to the English Channel and Great Britain. The temperature typically varies from 35°F to 73°F and is rarely below 24°F or above 83°F. Hydrangeas must love it.

Because of those two problems I had, I suggested going to the Atlanta Botanical Gardens in Piedmont Park to see if you might discover paniculatas planted there (or maybe find them while simply driving around town) and research how well do they do in ATL. Their panicle-shaped blooms are unique amongst hydrangeas so you can easily locate them when they are in bloom.... although the blooms do resemble oakleaf hydrangeas' blooms (but the leaves of the oakleaf hydrangeas are so much larger and different that you can very easily determine that the oakleaf plants are not paniculatas). Once you find some paniculatas in Atlanta, see how much sunlight they get in the summer.

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