Keep them in a semi-shady place, water as needed, remove ugly leaves, and wait until spring to see how they fared through winter. If you are in a cold zone then you may want to do some reading on this site on what to do for winter protection. If in a warmer zone then a bigger pot for winter would allow it to grow some more roots. That is unless you have a location to put them in the ground within the next few weeks - the sooner the better to get ready for winter.

Is that pot Vigoro? From Home Depot? Seems like they get a lot of hydrangeas in those pots and I've had problems with some of their hydrangeas.

It also looks like the people at the plant nursery were doing overhead watering on the leaves and they developed powdery mildew (I am referring to the grayish spots in the 1st picture).

http://www.clemson.edu/extension/hgic/pests/plant_pests/flowers/hgic2049.html

I would take them out of the pots. Check the roots - I will bet that they are very pot bound - circling around and around. Shake off all the soil, repot and make sure you do not block any of the drainage holes. Water well and I would also cut off all the leaves with mildew. Make sure that where ever you keep them - pots or the ground that they have good air circulation. Water at soil level - don't get the entire plant wet. They may shed all their leaves but will probably come back in the spring. I would also put in garage or basement for winter.

Thank you all for the suggestions.

It is Vigoro from home depot, only the 2 hydrangea in Vigoro pots have this issue. The other one is a forever and ever and it is looking good so far in the same conditions.

Forever, if you look at the soil level of the first photo you will see many branches coming directly from the root ball. Some are from this year and other - the wooden ones are at least one year old. I would think that this plant is at least 3 years old or so. The root ball can probably be divided - and looks like it would almost fall apart! Each division with roots attached should then be planted in a pot all by itself and all should grow. Use non organic potting soil and keep moist. This is the easiest way to make new plants and most importantly will help the very crowed plant in the original container. When buying plants from a big box store - and I do it myself - it is a good idea to pop the plant out of the pot and see if it is pot bound. Most of the time the people working in the plant department do not know much about plants. So if it has green leaves, it is watered to keep alive and sold. Staff in a good nursery will be well trained and monitor the plants so they do not get pot bound. But if you are careful and check the plants carefully, you can get some great bargains at the big box stores. Google the plant to find out how and where to plant it and what to expect in size, color and bloom - if it is not blooming.

Thank you. I am apprehensive of dividing the root ball, can I just repot in a bigger pot? I will also try to check out some youtube videos on how to divide root ball to check if it ready for a root division.

Should I wait until the leaves completely drop to repot/ pot up?

I was going to use the 5-1-1 soil mix recipe found on this forum, but that is not organic. Should I use 1-1-1 (gritty) mix for this?

Thanks!

You can pot up anytime. Dunk the root ball in water for an hour - at least and then replant in a bigger pot. Professionals nursery people have found that organic potting soil can burn new growth and are avoiding it in the trade when propagating new plants and I would while you are trying to save this plant. It is fine for repotting healthy growing plants - although I don't use it at all - unless it is a lot cheaper than the non organic soil . I am sure this statement will start some passionate conversations but remember, the 'organic' in potting soil and fertilizer is not regulated and can be of different strengths. Ordinary potting soil will do just fine. Breaking up the rootball into two or three plants is not difficult at all. Just pull apart and if they are too tight to pull, use a knife to cut them apart just make sure there are roots attached. By the looks of the pot on the top of your post, there should be NO problem doing this. Keep moist and you will be rewarded with two or three new happy hydrangeas.

If you can wait a couple of days - i will try to take some photos of root division tomorrow - Sunday.

That will be invaluable. Thank you!

Even if I don't manage to save these specific plants (though I certainly hope to), I look forward to my first root division.

I am trying to read up on the information about soil mixes on this forum. Quite overwhelming for a newbie like me. For this year, I am going to start with basic 5-1-1 mix and maybe next year venture into other adventures.

It looks like there might be some confusion with regards to 'organic' and 'inorganic' potting soils. If you take "organic" to mean comprised of natural materials, then the vast majority of potting soils are indeed organic, including the 5-1-1 mix. It is when you start adding ferts to the mix - like most of the Miracle Gro products or the addition of any CFR's (controlled release fertilizers, like Osmocote) that you start moving away from organics :-))

As we are at the beginning of fall, you want to avoid the use of any fertilizers that will stimulate new growth that won't have time to ripen or harden off before cold weather sets in. But just repotting in ANY potting soil that does NOT contain added fertilizers will be fine. Any fertilizing necessary - and anything grown in a container will require routine fertilization ( that's why companies like MG include ferts in their mixes) - should be left until the plant comes out of dormancy next spring.

Thank you Gardengal - much better explanation! The photos for root division will have to wait for a day or so but will be done in time for you to work on your plants. Several websites who demonstrate root division for Hydrangeas posted that they would wait for the plants to reach dormancy before dividing so there is lots of time - although I have done in full bloom and growth with no problems. A few days or even weeks should not matter. The photos that you posted showed new growth and the mildew does not look too bad and your plants should be just fine while they are waiting.

Thank you gardengal48. The basic 5-1-1 mix had optional CFR. So I ordered 'Dynamite All Purpose Select' based on some discussions here, but I will not add it now to the mix. Maybe I can use it later in spring by mixing it in water.

ophoenix - thank you. I will wait :)

You don't want to mix a CRF with water. That defeats the purpose of using them. They are all prilled or coated with a substance that dissolves over time and with soil moisture and temperatures - that's what makes them a controlled release!!

OTOH, you don't have to use a CRF - that just reduces the frequency of fertilizing. One application in spring can last the entire season, usually. But any kind of liquid or water soluble fert will work just as well - you just apply it more often. And if you want to increase the container soil acidity to encourage blue flowers on those kinds of hydrangeas, Miracle Gro for Acid Lovers (aka MirAcid) works very well.

I wasn't thinking, that certainly makes sense about CRFs! Thanks.

I was going to repot some hibiscus, gardenia into 5.1.1 mix and bring them inside before winter. For these plants and for some house plants, can I add CRF into the 5.1.1 mix for these plants? I understand what you are saying about not really needing CRF. But since I have already ordered it online, wondering how I can use it appropriately.

Thanks!

I'd wait until spring before applying. You don't really need to use any fertilizer at this time of year when plant growth slows and most are entering a period of quiescence or dormancy.