Growing Hydrangeas in Containers

Jul 19, 2016 | Gardens

You say you live where it’s cold, so the blue hydrangeas you plant never flower? Do you want to grow mophead or lacecap hydrangeas but you’re just a bit too far north? The solution is to grow these wonderful shrubs in containers.

I placed several of my potted hydrangeas under the grape arbor this year. They get direct sun in the morning or late afternoon, but love the filtered sunlight during the heat of the day.

I placed several of my potted hydrangeas under the grape arbor this year. They get direct sun in the morning or late afternoon, but love the filtered sunlight during the heat of the day.

First, get a large pot that’s light weight. Choose a good looking one because these attractive plants deserve a pot that enhances their appearance.

Next, be sure your container has drainage holes, and don’t cover them with anything. Use a good quality potting mix (I use COAST OF MAINE INC – Premium Blend Potting Soil, 8-Qts. or Espoma AP8 8-Quart Organic Potting Mix) and plant your hydrangea, filling the entire pot with soil from bottom to top. Don’t put rocks, shards or mulch in the bottom first. (If you think you need that “for drainage, you really need a copy of Coffee for Roses: …and 70 Other Misleading Myths About Backyard Gardening !)

I also mix a handful of organic fertilizer into the potting soil before the pot is filled. Once your hydrangea is planted in the pot, water it well and place it will get at least 2 hours of sun, but not in the hottest part of the day. Hydrangea flowers last longest when they are protected from mid-day sun.

This BloomStruck hydrangea is in a foam pot that's made to look like terra-cotta.

This BloomStruck hydrangea is in a foam pot that’s made to look like terra-cotta.

Water your potted hydrangea deeply and well when it’s dry, and then wait until the surface of the soil starts to dry before soaking again. On hot days you might be watering every day, but in cooler weather every three or four days. Don’t let the plants get too dry and wilted or the flowers will brown prematurely.

This is a shorter growing lacecap with HUGE flowers. It's called Let's Dance Diva (just Diva to her friends).

This is a shorter growing lacecap with HUGE flowers. It’s called Let’s Dance Diva (just Diva to her friends).

Most potting soils are neutral pH which will produce pink flowers on the varieties that are changeable when in acid or alkaline soil. To keep your blue hydrangeas blue, use Aluminum Sulfate such as Bonide 705 Aluminum Sulfate, 4-Pound mixed at the rate according to the package. Know that the change doesn’t happen quickly, so give it a few weeks to work.

In the fall, once the leaves color and fall off of your plant, pull the pots into an unheated garage or other space that’s cold but doesn’t go much below 35 degrees. Check the soil every couple of weeks and water if it’s dry, but leave it alone when it’s still moist. Don’t cut the canes of mophead or lacecaps down at this point – leave as is or you’ll be removing the flowers that will open the following summer. The only pruning you should do is in the spring to remove dead wood that has no leaves on it.

Your hydrangea might start to break dormancy inside in the spring. If it’s getting some light, leave it where it is. If you’ve stored it in a dark place, however, bring it into a room with a window.

You can over-winter Hydrangea paniculata plants in pots as well. This is a Bobo, one of my favorite short paniculata varieties. These white-flowering hydrangeas bloom on new growth so you can shape them a bit in the spring if desired.

You can over-winter Hydrangea paniculata plants in pots as well. This is a Bobo, one of my favorite short paniculata varieties. These white-flowering hydrangeas bloom on new growth so you can shape them a bit in the spring if desired.

When you pull the potted hydrangea plants outside after all danger of frost is past, place them first in the shade. After two weeks you can place them in part-sun and enjoy their flowers for another summer.

You say it sounds like too much trouble to bring pots of shrubs inside for the winter? My reply is that we carry lawn furniture inside to protect it, and these long-flowering shrubs bring such pleasure that they are worth some simple actions to enjoy their special flowers.

20 Comments

  1. Eric Krohne

    If a Hydrangea blooms on new wood, should all old wood be cut back each spring? That is to say, why keep old wood if the plant will blossom on new wood? Thank you, Eric

    Reply
    • CL Fornari

      Good question, Eric! The reason for not cutting the plant back to the ground every year is several-fold. First, the new growth that it would produce each year would be weaker, fresh wood, which is more likely to be bent over by the weight of the flowers. Secondly, that old wood holds energy that the plant uses when it breaks dormancy the next spring. And finally, it’s what makes the nice shape of a plant – it’s what makes a Pee Gee Hydrangea tree possible, for example.

      Reply
  2. Jane Knowling

    My plant store told. Me to plant my bobo in a mix of compost and top soIL then here it says potting soil .which is it??
    They also told me NOT to take my bobo into the garage in the winter but to put it in a protected spot .I live in Cincinnati .
    Help

    Reply
    • CL Fornari

      Jane – we know how confusing it can be when you read what seems to be contradictory advice. Here’s the truth: every confirmed gardener or plant person has their own method that has worked for them and so that’s what they preach “as gospel.” But the reality is that with plants (and the rest of life) there is no one right way. Mixing compost (organic matter) and topsoil comes pretty close to using potting soil. We recommend potting soil because it’s easy, already mixed and better yet, there are no weed seeds. Some top soils might contain weed seeds. Also, a good quality potting soil has been formulated according to industry standards for containers. So we find that for the general public, this is easy and helps them toward success. But that’s not to say that making your own isn’t OK too.

      In terms of overwintering, a Bobo might make it outside in Cincinnati in a container. We were talking about the blue hydrangeas as needing to be pulled into shelter for the winter as they are not as hardy as the Hydrangea paniculatas. And depending on the size of the container, a Bobo might come though the winter better if it’s in a more sheltered spot. The larger the pot, the more protected it is if you leave it outside, but smaller containers are more vulnerable. Again, we error on the “how to have people be successful” side of things.

      When it comes to plants and gardens, plants often thrive against all odds and some that are totally babied and catered to die. So there we are. With living things we do our best knowing that there are no guarantees. And while doing our best we hope for the best, and then sit back and enjoy the ride.

      Reply
  3. vivian gerard

    MY BOBO HYDRANGA DID NOT OVER WINTER VERY GOOD AT ALL LEFT OUTSIDE IN A CONTAINER THIS PAST WINTER I HAVE BEEN WATERING IT ALOT BECAUSE I DONT WANT TO LOSE IT WILL FIND A SPOT IN THE GROUND TO PUT IT THIS YEAR IN THE FALL I LIVE IN BC CANADA ZONE 8

    Reply
    • CL Fornari

      If you plant it in the ground – do so soon so that the plant can get roots established before winter. Plants in containers are more apt to make it though the winter if the container is large. Some people also group containers in a sheltered place next to the house so that they are as warm as possible. If it doesn’t rain frequently in the fall or winter, and the soil isn’t frozen, they may need water – if the soil dries out the roots will dry up too.

      Reply
  4. Jane Knowling

    Hi
    its Jane again SO i ought to bring my potted Bobos into my garage it seems -right? I live in Cincinnati

    Reply
    • CL Fornari

      I would bring them into the garage, yes.

      Reply
  5. Dennis Norling

    I have a potted macrophylla hydrangea “zebra” which was a nice plant but it had never bloomed. Last year after the first freeze (zone 5) I brought it into the garage. I think it was in late winter that I moved it to a very sunny spot in the house and by May it was covered with beautiful large blooms. My question is how important is it that I let the plant go through a hard freeze? I’ve just moved a dozen potted hydrangeas into the garage before the first frost. Is it important that they experience freezing temperatures before they go dormant?

    Reply
    • CL Fornari

      Dennis
      It’s not important to let this go through a hard freeze. I usually bring them in once the leaves yellow and start to fall, and sometimes this is before a hard frost. Colder temps and shorter days are telling them to go dormant. Ease off on the watering a bit (although don’t ever let the pots go bone dry or the roots will die) and they should be fine inside now.

      Reply
  6. vivian gerard

    what is there for a pink flower that likes shade and it likes to be in a pot

    Reply
    • CL Fornari

      Vivian – if you want an annual, begonias are the plant for you. There are many with pink flowers and these do well in pots in the shade. If you want a hydrangea, one of the CityLine series would be good – check out CityLine Paris, or Vienna.

      Reply
  7. Wendy Degenstien

    Can I grow one indoors ?

    Reply
    • CL Fornari

      Wendy,
      Unfortunately these plants don’t do well indoors long-term. So not a good house plant.

      Reply
  8. vivian gerard

    yes i have the cityline paris and love it so pretty my neighbors even bought one it blooms so good i just checked my new bobo that i have in a container i think its dead how do i tell

    Reply
    • CL Fornari

      Vivian,
      Don’t assume the Bobo is dead just yet – they are later to break dormancy than the mopheads such as the Cityline series. Water the soil that the Bobo is planted in if it’s dry. Keep it moist but not sopping wet – if the pot is in a saucer, empty out the water that remains in the saucer one hour after watering. Once the winter is over in your area (no more below-freezing temperatures) pull the potted Bobo outside. If it’s still alive it will develop leaves this spring. (May, if you live in the Northeast or upper midwest) If it’s dead it won’t grow leaves even once it gets warm.

      Reply
  9. Jane Knowling

    Ok so its late May 2020 very cold spring.
    My garaged container Bobo died.
    The other 2 kept up against the pergola and seem ok i did prune them in late March .
    Now are in leaf but had to prune again a lot of dead branches.Should they be transplanted to the ground in the fall? Or next spring ?
    Will they survive being transplanted or should i buy new and if so when?

    Reply
    • CL Fornari

      If they are alive and you want to put them in the ground do so now.

      Reply
  10. Elizabeth Mbewe Zingel

    Hi..I just bought hydrangea and I live in Lusaka Zambia (Africa)..I potted my white and pink Hydrangeas and the gentleman I bought it from said not to use acid soil and he sold me a bag of compost for potting ..please advise if hydrangea can survive the African/Zambian heat

    Reply
    • CL Fornari

      Well, Elizabeth, all you can do is wait and see, right? Place it where it gets morning sun but afternoon shade (shade after about 10 AM), be sure to water it well when the compost starts to get dry, and hope for the best!

      Reply

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