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Force Hydrangeas to go dormant?

Posted by msalcido 7/8 (Dallas/Ft.Worth (My Page) on
Sun, Dec 5, 10 at 9:57

Is there a way to force the hydrangeas in the pots to go dormant? With the exception of one, all the potted ones are still green and have lots of leaves on them. I'm concerned this will effect them for next Spring and I won't have any blooms?

Temps are in the low 30's this week and I have brought them all inside. They are in a room that gets sun and of course has the house temps which is kept between 68-72 degrees. Should I move them to garage where it is colder but doesn't get any sunlight? Also, the vent to the clothes dryer goes into the garage, will the hot air effect them in a bad way?

As always thanks for all the help!


Follow-Up Postings:

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RE: Force Hydrangeas to go dormant?

I'd leave them outside and only provide protection, like a unheated garage, if the temps plummet. Inside you cannot possibly encourage them to go dormant :-) Dormancy is triggered by shortened daylength and cold temperatures, which are seldom found indoors. As to requiring dormancy, most plants from temperate climates do require some period of cold temps and dormancy. However, my sister in zone 10 SoCal has numerous hydrangeas in her garden that never seem to experience a full dormant period like mine do and yet they flourish and bloom well.

btw, woody plants when dormant do not require sunlight. That is far more of an issue when in leaf, as sunlight is required for photosynthesis. When dormant and out of leaf, the plant is in a condition similar to suspended animation - no photosynthesis and very little root activity going on.


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RE: Force Hydrangeas to go dormant?

  • Posted by msalcido 7/8 (Dallas/Ft.Worth (My Page) on
    Sun, Dec 5, 10 at 13:22

thanks gardengal. I've moved them back outside. When you say plummet - what temperature are you speaking of? The low for tonight is supposed to be 30 degrees. Tomorrow 31 degrees for the low and then back up in the 40's. Should I put them in the garage?

please forgive all the questions, this is my first winter with hydrangeas.

Thanks again!


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RE: Force Hydrangeas to go dormant?

Right around freezing is fine.......anywhere in the lower 30's. If it should get down into the 20's for any length of time, I'd be concerned then. And if you have a covered porch or something similar, I might not be concerned even then :-) I grow a lot of stuff in containers - have for years - and they do just fine. Have even survived a number of days/nights in the 20's without problems. But then, I do use pretty large containers for most of my stuff and I group them all togther during winter. That creates a bit of microclimate with the transpiration.


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RE: Force Hydrangeas to go dormant?

  • Posted by morz8 Z8 Wa coast (My Page) on
    Sun, Dec 5, 10 at 18:56

I'm in gardengals same zone, and I don't worry in the low 30's or even upper 20's....neighborhood of 28ish if we are talking only about dipping to those numbers briefly overnight and not extended round the clock freezes for a few days - as happens rarely but did recently.

Much below 28 and I move things either up against the house, or out of freezing winds into a carport and cover temporarily with old tablecloths. I've used a large lidded plastic tote too, again - temporarily and just until the storm passes. A neighbor has had good luck just tucking pots of things she might be concerned about under her large and dense rhododendrons, even that evergreen foliage will add a few degrees of protection.

One particular winter night as an arctic blast was settling on us without much warning, I put young containerized rooted cuttings into the back of my SUV in that carport for added insulation - that was about the best I could come up with in pajamas without resorting to bringing plants into a too warm room :)


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RE: Force Hydrangeas to go dormant?

I've never been to Dallas, but I'd bet that you could just leave the plants outside for the whole winter and never have a problem. (You might put some mulch around the roots in the pots to keep the root ball from freezing, but I'd bet that's not even going to be a problem.) Upper 20's should never be a problem for you. If this were to happen after a month of 90 degree days, then you might have a problem, but not if the plants have had a chance to move into the winter pretty reasonably.

I overwinter my potted plants outside, covered up with bags of dry leaves. I don't even think about covering them up until I see that the temperatures are going down to about 20 degrees....and I'm pretty sure that I put them away too soon at that.

Keep in mind that plants do quite well at Cape Cod and New York City. Go to your weather service and check out the temperatures there when you begin to worry about yours.

Hay


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RE: Force Hydrangeas to go dormant?

Thanks everyone. I'm not sure how I missed the first two replies. Well it hasn't dropped past 20 degrees. We have been in the upper 20's here in Dallas. I've moved all the potted plants into the garage and they are finally losing the leaves and turning woody. I think they are doing good. This weekend it is supposed to rain and on Monday it's suppose to drop into the teens, so I guess I'll leave them in the garage.

Thanks again!


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RE: Force Hydrangeas to go dormant?

Just to clarify......it is not so much concern for the top growth and potential damage to latent flower buds at temps into the low 20's but rather root damage. Plants grown in containers are at risk from root damage when temperatures drop too low and stay there for more than a night or two. Without the insulating properties of all that soil mass around them, roots of containered plants are often more vulnerable to cold damage than is the top portion of the plant - and root damage can have far more serious results. For many woody plants, this damage can occur around 26-24F.

Leaving them in the garage during the coldest weather is a sound idea :-) And it won't hurt to leave them there all winter, if you prefer.


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RE: Force Hydrangeas to go dormant?

Thanks gardengal! I have them in the garage and they are all dormant. I've been watering once every week but not much. I can't wait until Spring for new blooms and to be able to move them back outside!

Thanks again!


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RE: Force Hydrangeas to go dormant?

What about watering? I brought my potted hydrangea into the unheated garage as we have temps in the teens and low 20s regularly. Do I need to give it water or should I just let it sit quietly till spring? Thanks in advance.


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RE: Force Hydrangeas to go dormant?

Hi ellen218,
absolutely water it. it's very important that the hydrangea gets water during dormacy. They still need moisture. I water about once a week and not very much just enough to get the roots wet.


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RE: Force Hydrangeas to go dormant?

Thanks, hope I haven't killed it! I guess we wait till spring and cross our fingers.


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RE: Force Hydrangeas to go dormant?

How long had it been since you watered? If it were just a week or two, it should be fine. Make sure to water weekly from now until you set it out for Spring.


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RE: Force Hydrangeas to go dormant?

You can insert a finger into the soil and water if it feels almost dry or dry. In my attached garage, it seems like I have to water around every 9-ish days. Nurseries also sell gizmos that change color when the soil is dry. You could try to see if these things works for you.


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RE: Force Hydrangeas to go dormant?

OH, I brought it in probably around the first of December and haven't watered since. I read somewhere not to water till February, so I just let it be. Now I'm watering once a week along with the ferns that I'm keeping alive in the garage. I appreciate the advice.


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