Watering During Extreme Heat

10 years ago

Hi All,

I've always followed the general rule of 2 gallons of water per rose bush each week. So much, to the point that I use a watering can so I know how much I have delivered.

If we have a good soaking rain, then I will skip a watering.

Here's my question. We have had several days of extreme heat and no showers or thunderstorms.

While the roses still look ok, I worry that they are need some additional water.

Is it ok to increase their water supply during these "dog days", or best to let them go?

Thanks!

Scott in PA

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Comments (11)

mad_gallica (z5 Eastern NY)
10 years ago
How's the humidity there? Here it is almost like swimming in air. NOTHING dries out in those conditions, or loses water. We've gone weeks and weeks in weather like this without rain, and without any wilting (at least on the part of plants).

The fun comes when this weather breaks and it get much cooler and much drier. Then everything seems to dry out fairly quickly, but most people don't water because it is much more comfortable for them.
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DNTQuilter
Original Author
10 years ago
The humidty has been high. You know, I never thought about the humidity contributing to keeping things wet. Of course, the annuals I've been giving daily drinks, and they appreciate it.

The roses don't look all that dry, but gosh, I'm learning what the high heat does to the beauty and stem life of rose blooms. Yuck!

Scott in PA
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Join the club, gwhext; you are not the only one with hydrangeas stressed out and-or partially dried out. Even at the Dallas Arboretum they are suffering. Some of those dried out stems may still leaf out so I would just let them be until around mid-May 2012 to see if anything happens. Expect some leaf out from the base when stems dry out. If you just cannot wait to tell if the stems are dried out or not, prune them in 1" or 2" increments but stop either when you get to the bottom or when you hit green. Make sure the shrubs are well mulched, with 3-4" of mulch as this reduces the amount of waterings needed. So instead of watering twice a day say, you may need to water every "X" days instead. But I think you are watering too much (twice a day). If your soil drains well, that may be ok but otherwise they could develop root rot due to the clay soils so just be careful. Oakleafs will croak if left in wet soil for too long periods but mopheads are more forgiving. You basically do not need to water if the soil is already moist when you insert a finger into the soil to a depth of 4". If they wilt -as mine do- during the day, that is ok. It is a form of defense mechanism and they usually recover by next morning. Water if you see an extreme looking wilting episode; otherwise check the soil moisture using the finger method. About 1 gallon and half per watering should be enough. When the temps go down and stay down, you can go down to about 1 gallon of water per watering. If the shrubs are getting sun past 11am or so, consider moving them to a more shaded location or temporarily using shade cloth. You can wait until winter to move them since the plant will then be dormant and it will be less stressful for the plant. Expect poor bloomage in Spring 2012 as result of all of these problems. Rebloomers may be in better shape; blooms from old wood may be toast but blooms from new wood in late Spring should be fine. Of course, I am assuming we do not go thru another repeat of 2011 next year. And that we get some rain and water rationing does not get worse... Good luck, Luis
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jim1961 / Central Pennsylvania / Zone 6
10 years ago
Hi Scott,

This part of PA has received 5-6 inches of rain within the
past 2.5 weeks... I have 6 roses looking real bad out front from probably too much water... Might be fast spreading BS or water logged soil...
Knockouts and Mister Lincoln still looking good but everything else looking sad right now...
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jacqueline9CA
10 years ago
As long as you have good drainage (which will prevent waterlogged soil from hand watering), I would go ahead and give them more water.

Jackie
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Maude80
10 years ago
Scott, one of the things that I've found very helpful with my roses is newspaper and mulch. Around all of my roses I have layers of newspaper (usually around 5 sheets thick) covered with several inches of mulch. This not only helps to retain moisture, but it also keeps the ground a bit cooler so that these brutal temps aren't as harmful (it's 94 today here in zone 5b)..

Maude
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socks
10 years ago
Find a spot between a couple of the bushes and dig down a few inches to see how much moisture is there. I know you don't want to water if it's unnecessary but don't want the bushes to be too dry either.
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DNTQuilter
Original Author
10 years ago
Jim,

So sorry to hear about your roses. Many of the heavy storms in the past weeks went north of us, and we didn't get near the rainfall that you did.

Hoping things dry out for you and the roses turn around.

Scott
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DNTQuilter
Original Author
10 years ago
Jackie,

Thanks for the advice. I think I will hot hesitate to give an extra drink if mother nature pulls this crap again.

Maude,

I like the newspaper idea. Of interest, the Rose Dr. at our local nursery advised me to keep the mulch pulled back away from around the base of the rose. Why? He said that the heat makes it too hot for the plant when surrounded to the trunk with mulch. I have not followed his advice. Although, the mulch is not as thick around the base since I move it away when I work Rose Tone into the soil each month.

We had a big storm here this afternoon. Where was I? The Garden Center at Lowes. I just picked up two Dwarf Ornamental grasses to put in the rose garden.

It was amazing the amount of water that came down in that storm. No watering required here.

Scott in PA
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jim1961 / Central Pennsylvania / Zone 6
10 years ago
Mulch up against the canes could help breed fungus...
Like canker, etc...
So I've heard... Not sure myself one way or the other?
I keep the mulch a few inches from the canes just in case...lol

This post was edited by jim1961 on Sun, Jul 7, 13 at 21:29
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Maude80
10 years ago
I keep the mulch a bit away from the canes too. I'm not sure if it really will cause any sort of disease, but better safe than sorrt:)
Maude
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roseblush1
10 years ago
The two gallons a week is a "rule of thumb". Some roses are more thirsty than others and may require even more water. Besides, roses can't count.

Along with humidity, there are other variables like the size and maturity of the plant, whether or not the temps drop at night and allow the plant to rehydrate the top growth from moisture in the root zone, whether the plant gets afternoon shade ... and more.

If the plant is losing more moisture in the top growth due to transpiration ... sweating .. than it can pull up from the root zone, then you may see some wilting during periods of high heat. In my climate, night temps can be 40 to 50 degrees cooler than the day temps. This gives the plant the opportunity to pull the moisture that is around the roots up to the top growth and by morning, the rose will be fully hydrated again and there will be no sign of wilting until later in the day when that transpiration rate stresses the top growth again.

As far as mulch being pulled back, it make sense not to have wet mulch right next to the base of the plant because it could cause disease in some climates, but more important, the feeder roots that pull up moisture and nutrients spread out and away from the base of the rose. That's the soil that needs to be kept moist and cooler.

Living in a low humidity climate with day temps in the 90s and low 100s for the summer months, I generally give my roses a deep watering once a week and what I call a "feeder root" watering mid week to put moisture into the top few inches of the soil under and around the roses. If we have triple digit temps for several days, since I already have to wash the roses to avoid spider mite infestation, I wash them in the afternoon because roses also absorb moisture through their leaves.

Yes, I do get some crispy blooms, but I try to grow roses with blooms that can handle the heat in this garden.

Smiles,
Lyn
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Watering During Extreme Heat

Comments (11)

mad_gallica (z5 Eastern NY)

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