Over-Wintering Plants In The Garage

Jan 24, 2017 | Gardens

At this time of year my garage is packed to the rafters. Sure, I have the usual assortment of snow shovels, ladders, fertilizers and other garden products. There is a rack of boots, some brooms and the garbage cans…normal garage stuff. But from December through April, my garage is also packed with plants.

There are some plants that may not survive in containers outdoors, yet they don’t need to be in the house either. Some, like the fig trees (somehow we ended up with three large pots of Brown Turkey figs), lose their leaves and are dormant. Others, like the huge bay, are semi-dormant and do well enough by a small, eastern-facing window. Then there are the potted Hydrangea and Agapanthus: these are placed wherever there is a space, allowing that the cars do need to be able to pull in before a snowstorm.

In short, the plants are more stored in the garage than they are grown here.

Some plants are grouped near one of the eastern-facing windows. I guess “grouped” is a nicer term than “piled,” but the stacking doesn’t seem to bother the ones that are dormant and the top pot drains into the bottom one, making watering a bit more efficient. Or so I tell myself.

And they do just fine. The key to success with garage storage is that this area is attached to the house but not heated. The garage never goes below 32 degrees but tends to hover in the 40’s and low 50’s all winter. This keeps the plant dormant but the plants never freeze.

Watering is needed, but not too much or too often. I’ve found that if these plants are watered every three to four weeks, depending on the temperatures and the size of the container, that this is perfect for keeping the roots from drying up. Too much water is likely to rot the roots, however. When plants are dormant they are not absorbing much water, so if the pots sit in saucers that are filled with the overflow this can lead to root rot. Yesterday I had to use a broom to sweep excess water onto the garage floor and then out the door, since these pots are too large to easily move them out of the saucers so that they could be emptied.

The saucers under the figs ended up being flooded after watering. If I left this much water the figs’ roots would suffer. A broom quickly pushed the excess out and as a bonus, the surrounding garage floor got cleaned as I used a push-broom to move the water outside. Two-for-one!

Other than watering, the only tricky part of garage plant storage is what happens in February and March. As the days lengthen the plants start to break dormancy, even though there really isn’t enough light to sustain this growth. If the weather is fairy mild I can pull varieties such as roses and hydrangea outside to slow them down. But if it’s too cold they must remain in semi-darkness until the weather improves. At that point I need to gradually reintroduce them to the real world so that the leaves don’t get sunburned. I do this by grouping them near the garage door and opening it for short periods so that the sun can come in. I might do this for only fifteen minutes in late-March and moving to longer periods in April. Finally, once the weather is mild enough, but hopefully on a cloudy day, I move the plants outside for the season.

The Agapanthus stay green all winter. On an especially mild, sunny day we open one of the garage doors so they get some light. But keeping this plant in the cool temperatures of the garage is what helps them to flower well in the summer. People who live where it’s too cold to grow blue hydrangeas outside can use this method of over-wintering them in containers. The BloomStruck hydrangea in the foreground is spending the winter snuggled up to one of the fig trees. It would be bud hardy in most winters on Cape Cod but I’m growing it, and a few other hydrangeas,  in containers to show what those in colder regions can do. 

64 Comments

  1. Sue Clark

    I use an inheated room off my garage. Put begonias, geraniums and a pot of marigolds with seeds sprinkled on dirt. No watering till April when they get to go outside as long as not too cold.

    Reply
  2. Stephanie Simpson

    Perhaps a cool basement with several windows would do as well?..Im going to try it..Good ideas here…

    Reply
    • CL Fornari

      Absolutely, Stephanie – a cool basement with even a little light can be a good place for dormant plants. One key is to not put them down there too early however – let them cool off outside as long as possible without freezing.

      Reply
  3. vivian gerard

    i will put my hibscus in garage for winter

    Reply
    • CL Fornari

      Vivian,
      If your garage goes much below 50 degrees in the winter you’re better off keeping the Hibiscus in the house. Some plants do fine in the 35 to 50 range of the typical unheated garage, but tropicals don’t do well below 50. Hibiscus is one that does better indoors where the temps are warmer.

      Reply
  4. brenda hull

    I have a key lime bush and a tangerine bush I’m not sure what to do with. I do have a mud room with three windows but it gets too warm there because the furnace is in there . I do have a garage but I cant put the plants near the windows because of other things are there.

    Reply
    • CL Fornari

      Your key lime should go in front of a sunny window or slider in the house. Mine is in the kitchen by the sliding glass door! They need temps above 50 and sun.

      Reply
  5. K. Hunter

    I live in SW VA and the winters can be very cold. Today, I pulled my plants into the garage because of a forecast of frost.
    I have over – wintered them in the unheated garage for years but I’m always weary that the 9 year old mandevilla, the ferns, geraniums and spider plants will not make it. At the end of the winter , they usually are on their last legs.
    Any ideas for a heat source that would be safe and minimal – enough warmth to just keep there from getting so bedraggled ?
    I’m feeling bedraggled tonight after the plant move turned into a partial garage cleaning! Thanks!!

    Reply
    • CL Fornari

      Bucky’s Mom,
      I feel your pain. We spent two days cleaning the garage before the plants could come in! The spider plants and geraniums are best over-wintered in the house in front of a sunny window if you have the space. I would take a few of the “offspring” off your spider plants and put them in one pot for the winter, then separate and grow larger come spring when they are outside. I personally don’t usually over-winter the original geraniums but take cuttings, again, rooting six or more in one wide pot in the house and then separating them into new pots in April.

      And if the ferns are Boston Ferns, warmer temps are better for them as well. I end up with plants like these in my bathroom, laundry room and guest room. I suppose you could get the seed starting heat mats and plug them in, and keep the pots on them…which would be safe since they are made to be waterproof, but they are small so you’d need a few, and I don’t know what that would do to your electric bill.

      Reply
  6. Vadim

    Can a potted gardenia tree survive winter in the garage?

    Reply
    • CL Fornari

      Vadim,
      Usually yes – as long as the garage doesn’t go below freezing. They will look pretty sad by spring, but you can cut them back and fertilize when you put them outside in the spring. That said, the best way to overwinter geraniums is in a sunny window in the house.

      Reply
  7. M Kirby

    Does anyone use a grow light? We have only one window in the garage and moving the plants to a garage door is not feasible. I’ve got tropical hibiscus, bougainvillea, hydrangeas and others.

    Reply
    • CL Fornari

      M,
      Yes, you can use lights for those tropicals that will keep their leaves. The Hydrangeas should lose their foliage and be dormant, so they don’t need lights until they break dormancy in late February or March. You can either use grow lights or plain fluorescent lights – tube lights in a shop fixture should go fairly close to the plants (six inches to a couple of feet).

      Reply
  8. Mildred Broselow

    My Aunt lived in Maine and had a huge pot of geraniums that she overwintered for 25 years. It was gorgeous. I can’t remembe how she did it. It went into a cold shed and she never took it out of the pot. I can’t remwmber how she did. It! Could you help?

    Reply
    • CL Fornari

      Mildred,
      If she kept it from year to year her shed didn’t go below freezing. Many people save geraniums in cool places where they go pretty much dormant during the winter, and then they leaf out again in the spring. But they can’t be where it’s below 32. Also, if kept in the same pot you’d need to periodically add some new soil to top and fertilize.

      Reply
  9. JIM CLEMENTS

    Thank you for your wonderful article. I live in Amarillo, TX which is in zone 7A. I interested in putting plants in my garage, but our temperature in winter varies greatly. We have days in January and February that can reach 75 degrees and two days later it will be 5 degrees. then it is not too uncommon for the daily high to be in the mid-sixties for several days, i.e. 5-7. im afraid the plants will start to come out of dormancy during these warm spells. i would appreciate your opinion.
    thank you.

    Reply
    • CL Fornari

      Jim,
      The reality is that most plants will start to come out of dormancy in late February or early March anyway, because they sense longer days from any light that comes into a garage or shed, and because of the temperature swings. So my hydrangeas leaf out in March, as do the figs. How I handle it is that if I’m home on a hot day I’ll open the doors and let the plants get some real sunshine. If the temps are cold I keep the doors shut. I water the plants when they are dry, and later I’ll put them out into part-shade first so that the foliage that broke dormancy early isn’t sunburned by the “real world” conditions. So it’s a dance, but not a very complicated one.

      Reply
      • Collin Drew

        I’ve got a Hardy hibiscus appx 3ft tall in a planter, too big for house & unheated garage w/broken pull down door. Thinking of moving her to a metal framed shed, Still no heat & here in GA. it gets below 50, winter’s run 40 – 20 degrees.
        Once I move her to Shed, THEN WHAT? Do I Wrap her, give another top soil cover?? Thank You Soo Much!!

        Reply
        • CL Fornari

          Collin – if this is truly a hardy hibiscus, not a tropical hibiscus, why not just plant it in the ground outside? You can either leave it where you plant it, or dig it up in the spring and put it back in the planter. I don’t think you need to do the shed for a Hibiscus moscheutos.

          Reply
  10. Jan Baublis

    I was away all winter and stored some potted plants in my unheated garage……..It is early May and my potted Hostas have emerged!! They are pretty tall but have no color ( white!!) since they had no light. Can I save them if I put them out in heavy shade??

    Reply
    • CL Fornari

      Jan,
      They should be fine. Put them out in a fully shaded area at first – if it’s still below 45 at night where you are, you might want to put them out in the day and in the garage at night for 4 to 7 days, then move out into shade for good. Gradually introduce more sun. Don’t fertilize until the plants have greened up on their own.

      Reply
  11. Mary OBrien

    Hello
    I live in Chicago suburbs and am wanting to hold plants while I intentionally kill off and prepare a bed for next spring.
    I have a 3-season room attached to my detached garage. 3 sides are windows with eastern, south & western exposures.
    Do you think this environment would be well suited to harbor plants over winter?
    So far I’d like to host day lilies, hostas, peonies, Japanese lanterns, lemon drops and an assortment of ground covers.
    I’m just trying to avoid temporarily transplanting.

    Reply
    • CL Fornari

      Mary,
      That room would only be good if it goes to well below 40 and stays there. I’m worried that even if it’s unheated during the day when the sun shines in the space will go well above 50 and then the plants will start to grow. Isn’t there another place outside where you could dig a trench and park them in the ground? Either that or cluster them together and mound mulch on all the edges so that it’s 16″ thick, then top with a couple of inches over the group.

      Reply
  12. Nikki F.

    I have a very large potted hibiscus tree that is way too heavy and tall to bring in the house over winter. I have an attached unheated garage with 1 small window …how can I make sure it survives in a Chicago winter

    Reply
  13. Nikki F.

    I have a very large potted hibiscus tree that is way too heavy and tall to bring in the house over winter. I have an attached unheated garage with 1 small window …how can I make sure it survive in a Chicago winter

    Reply
    • CL Fornari

      Nikki – short of building a heated greenhouse around this plant, there is no way it will survive outside in a Chicago winter. Once the temperatures drop below 32 it will die, no matter how much mulch/protection you might put around it.

      Reply
  14. Brian Fisher

    Hello,

    I have a few tiger eyes sumac dwarf trees that I recently had to transplant from planter boxes on my roof deck into large Aeration fabric bags. I live in Chicago and will not be able to replant them on my roof deck until late spring. Will they be ok stored in an unheated, attached garage with no natural light. An artificial light is always on. Or, would it be best to take them to a friend’s deck and winterize them?

    Thank you so much for your advice.

    Brian

    Reply
    • CL Fornari

      Since they are dormant in the winter and don’t need light, you could put them in the garage but unless they start to break dormancy in February or March, leave the lights off. Lights would encourage them to grow at the time they should be resting. Of course, if you have a “Polar Vortex” period like last year (I was in Chicago for that!) they might not make it. But better in the slight protection of the garage than outside. Putting something like bubble wrap around the fabric pots might help…

      Reply
  15. Betsy W

    I live in zone 8A and have 3 tropical hibiscus plants in pots that I bring in each winter. My garage has no windows so I keep a couple of lights shining on them through the winter and water them less often. When it starts warming up in the spring I’ll open the garage for a bit and then bring them back outside. I usually trim them down about 1/3 when I bring them back outside. Does all of this sound okay? I wish I could put them in the ground so they could grow better because I know they’re very root bound having been in the same pots for several years. I can’t repot them because if the pots are any bigger I can’t move them by myself. I’m fairly new to gardening and am just looking for advice!

    Reply
    • CL Fornari

      Betsy,
      Sounds like you’re doing things well, but I understand about bigger, root bound plants. Most tropical hibiscus are true zone 9 plants, so it’s unlikely that you’ll be able to grow them outside through the winter. I know that most people don’t like throwing plants away, but it’s always an option when a plant gets too large to leave it outside (maybe planted in the ground) and if it makes it that’s fantastic and if it doesn’t, oh well. Then you start with a new one in a pot that is smaller…at least at first! Enjoy!

      Reply
  16. Cathy Oelze

    When do you move them back outside. Went out in the garage and have a small hydrangea and the leaves are starting to sprout out on them. Zone 5

    Reply
    • CL Fornari

      Cathy,
      Don’t move the hydrangeas out until you see the ones outside opening their leaves – once the plants that are growing outside have leaves the size of a quarter, you can put them out. Let them do what they will do in the garage. Don’t overwater and don’t give any fertilizer. Once you put them out, put them in the shade at first, and move gradually to more light so the leaves that opened in the garage don’t get burned.

      Reply
  17. Maria

    I live in Southeastern NH about 30 minutes from the coast. I have a bunch of perennials that I have over wintered in my garage. When will I know when it’s warm enough to move them outside for the summer?

    Reply
    • CL Fornari

      Move them out now so they can break dormancy outdoors. If you see that the temperatures are going to fall into the 20’s overnight, or that daytime temperatures will be below freezing, put them back in the garage. But in early April this would be unusual, so get them out soon.

      Reply
  18. Maria

    Thank you! Just put them outside. Do I water them and prune them now too?

    Reply
    • CL Fornari

      Remove any dead leaves and stalks – assuming these are not “woody” plants such as lavender or shrubs. Water when soil is dry.

      Reply
  19. Christine Manlove

    I have a full eastern and a full southern-facing window in my unheated garage. I want to winter over geraniums and two hibiscus plants, potted. Should I place them right next to the window for direct sun or further away for just light? and is the eastern or the southern window better. If not directly next to the window, how far away> The garage is attached to the house at the basement level which does not god below 60 degrees. Not sure what the garage temperatures are in winter. I live in Batlmore, and recent winters have been mild.

    Reply
    • CL Fornari

      In front of the window will be great – put trays under so you can water them well when dry. If they’re in sun the soil will dry out faster than if not in sun.

      Reply
  20. Jemara Blount

    What about an Inclosed patio that gets a good amount of light?

    Reply
    • CL Fornari

      Jemara – it all depends on how cold it gets. You want a place where the temperatures are below 50 but above 32 f. If your patio goes below freezing the roots of your plants will freeze and the more tender plants will die. If it’s a sunny room the temps might swing drastically between very warm in the day and cold at night – and that can be hard on many plants. So keep track of temps in the winter and you’ll have better information.

      Reply
  21. Wilda Gregory

    I have a huge aloe Vera plant that I cannot put in the house. Can it be stored in the garage?

    Reply
    • CL Fornari

      Wilda – only if your garage has a window and doesn’t go below 50 degrees. Since Aloe is evergreen and only rests, but doesn’t go dormant, you’ll need it in some light. It doesn’t have to be a lot of sun, but you do need it in light and this plant doesn’t want temps lower than 50.

      Reply
  22. Julie D

    I have two large citronella plants and a garage with no windows. Our basement has a very small north facing window. Any chance they’ll make it through the winter in the basement?

    Reply
    • CL Fornari

      Give it a try – no harm, right? Place them as close to the window as possible and know that they will lose leaves.

      Reply
  23. pam throne

    I have a Little Miss Figgy dwarf plant. I live in NW Arkansas. Now it’s in a pot on our deck and doing great. What is best to do for the winter?

    Reply
    • CL Fornari

      I don’t know your weather so hard to advise…call your local garden center.

      Reply
  24. Lisa Pluth

    I live in Northern MinneSNOWta and as of today (10/19/20) we have 4″ of snow on the ground and more coming. My predicament: I have 4 cinnamon ferns and two clematis on the way. Is it safe to winter these in my garage if I am unable to get them in the ground before it freezes up here?

    Reply
    • CL Fornari

      Lisa – you still might be able to plant them – 4″ of snow in no way means frozen ground. But if you can’t, put them in potting soil in pots that are about 8 to 10″ in diameter with fresh potting soil, water them well and keep them in an unheated garage. Check them every couple of weeks to see if they need water – the soil should be moist but not wet. They might start to break dormancy in the garage in March – just let them do what they do (don’t bring them into the house) and then put outside in April or when the temps are above 50 degrees.

      Reply
  25. Carol Kluchka

    I have 6 plain green hostas,9 hybrid lillies and many more perennials to dig to get ready for foundation work and deck removal and expansion..
    I’m putting them in large plastic storage bins,no lids, with a drainage device underneath each group ?putting in the garage and basement.
    I think I’m good on the temperature and light scenarios. Just don’t know how I’m going to get it all done and plant tulips in this cold weather already in Milwaukee Wi !

    Reply
    • CL Fornari

      If these were mine, I’d find a place outdoors to heal them in. Edge of a vegetable garden, for example. Then they’d go through the normal dormant period perennials do and can be transplanted next spring. And I get Wisconsin weather…I’m from Stevens Point.

      Reply
  26. Anne Roberts

    I have large pots of Clematis. Would our unheated sunroom be a good place to winterize them? Or would it be better to place them outside on deck by the wall of the house—with blankets? And, what would be the instructions on watering in sunroom and outside on deck? Thank You!

    Reply
    • CL Fornari

      I don’t know what type of Clematis you have, but if I had them in pots I would not keep them in a sunroom where day temps are high. I’d keep them outside, or even bury the pots in the ground for the winter instead of blankets.

      Reply
  27. sahran shaoul

    Do potted fig trees in containers need to be covered in total darkness ( inside box enclosure) in the garage during the winter? or is it ok to keep them uncovered in the garage during the winter? Thanks

    Reply
    • CL Fornari

      Dark isn’t needed. Just cool temps that are above freezing.

      Reply
  28. Anni C

    Thank you for this helpful article and the many comments/answers! I may be imagining that I can see a potted gaura in one of your photos, because that’s my current dilemma. I purchased one this summer that was a replacement for something unavailable and it arrived late due to the pandemic gardening frenzy. Since I wasn’t sure where it should reside permanently, I potted it in a large metal pot with a green patina that I forgot I had and set it in the sunny border of a garden space, and it’s gorgeous there! Will it go dormant such that I can bring it in my unheated central Illinois garage with no natural light? I thought of burying the whole pot where it is. We’ve had a few freezes, but it appears healthy for now. I also have a moonbeam coreopsis in a large wooden deck planter. It’s the only perennial in the planter, and we would like to tarp the planter for protection. Can I leave the coreopsis in the potting soil under a vinyl tarp over winter or should I tranplant it to the ground and mulch it for winter? I’m afraid the lack of circulation under a heavy tarp will cause mold or rot, and I’m afraid uncovering it occasionally during breaks in freezes and snows will cause more harm than good.

    Reply
    • CL Fornari

      Anni,
      No, there wasn’t a Gaura in my photos. In my warm Zone 6 garden white Gaura is hardy, although I consider it a short-lived perennial. (Three to five years.) The pink Gaura is not hardy for us and I don’t even try to keep it as it’s widely available in the spring at the garden centers. Note that because Gaura blooms for so long, it behaves more like an annual. If you want to keep it, yes, put it in your garage (coreopsis too – another short-lived perennial) – DO NOT CUT THEM BACK – Do not put a tarp over plants – prevents water from getting to the roots and doesn’t protect them at the end of the day. Also, in February when the sun gets warmer the plants can cook under the tarp…just like your car heats up from the sun in February even when it’s cold outside.

      Reply
  29. Louis Galarneau

    Hello, I live in Canada north of Quebec in very cold area -40 in winter and very windy” I bought the summer 50 roses David Austin . At the End of October when the nights start to be below freezing point I have put them in my heated garage which I keep close to freezing point 32F ( 0C) all winter. Until now ( Nov 28) my rose look very fine all canes are still green. . Note that I have remove all leaves to force them to go dormant faster and avoid sickness transmission ( Black spot etc) . I have install an artificial light system with a timer, which I plan to start not before mid march to give them a daily little light period when my garage will start to warm up by itself in spring and that it will be still to early yo bring my roses outside because the outside nights will still be to cold . I cross my finger and wishes myself success. LOL

    Reply
    • CL Fornari

      Louis,
      Sounds like you’ve got a good plan! Note that I have many plants that break dormancy in February, March, and April in my garage and are in very little light (one side window 12′ away from all plants) but when I introduce them gradually into real sunlight in May, they do just fine.

      Reply
  30. Jeanne McElroy

    I put my hydrangea in the basement to go dormant. Room stays in the 50’s and it’s dark for the most part. I water it about once a month. Today I found new growth so not sure if I should bring it into the light and start watering more in a sunny window or cover to make it darker to try and retard new growth. It’s only the middle of January and I’m in Ontario Canada

    Reply
    • CL Fornari

      Jeanne,
      Mine always break dormancy in the garage sometime in February too. I leave them there, where they grow pale leaves and I continue with minimum watering. Once the weather warms I introduce them gradually to “real sunshine” by putting them by the garage door and opening it for an hour or two during a nice day. I can’t say what would be best for you, but what I can tell you is how I manage mine, and if I was in your situation I would not bring it up to a warm place this early.

      Reply
  31. Larry Arcement

    Thinking of starting bamboo(supposedly hardy for boston,,zone 6) in planters this spring .considering using ~2′ long planters so they can be moved to ~45-50 degree garage with only small windows in garage doors during winter,.will this be sufficient or should I try to leave outdoors & mulch /insulate heavily somehow? Thank You

    Reply
    • CL Fornari

      Larry – In general plants grown in containers that are left outdoors over the winter must be hardy two zones colder than where you are. This is because even in insulated containers the soil gets about 20° colder than ground temperature. If you leave these outside over the winter the bamboo is likely to die.

      Reply
  32. Lynn Haley

    I have a Dipladenia and a tree hibiscus that I have overwintered in my garage and successfully brought out in mid-March and they have done perfectly the past 3 years. This year when I brought them out of the garage, the roots are getting a little too big for pot so I did some light root pruning, pulled some of the old soil out of roots and repotted in fresh potting soil. Then fertizilized with Miracle Gro. They have done nothing, no green shoots. Bare as can be. When I scrape some of the branches, I can see green so I know they are not dead. It is now May and still no green growth. Did I throw them into shock? If so, can I do anything? I live in North Carolina in Zone 7.

    Reply
    • CL Fornari

      It takes plants awhile to recover from root pruning. Be patient!

      Reply

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