Container gardens continue to remain popular as those with smaller properties are still able to enjoy greenery this way, but they do have special needs when the temperatures begin to drop.
Unlike plants in the landscape, those in containers are more vulnerable to having their roots freeze as the soil hardens more above ground.
Depending on your customer’s available space, they have two main options when it comes to overwintering plants in containers: bring them indoors or protect them outside.
If your client wants to bring their container plants indoors, caution them that there’s a little more to it than simply moving the potted plants from the patio to the living room.
First, the temperatures need to be dipping below 60 degrees Fahrenheit regularly before they need to worry about any great migration indoors.
When it comes to determining which should stay and which should go, focus on keeping only the healthy plants. Those that have been struggling throughout the summer will only become more stressed by indoor conditions. It is best to put these out of their misery. The same goes for plants with pest or a disease your client thinks they can save.
When prepping plants for the move, advise clients to look for unwelcome hitchhikers like mealy bugs or spider mites. They can also soak the pot in lukewarm water for around 15 minutes to cause bugs to scramble to the surface for oxygen.
As for where your customer should put their containers, those that need full sun should be placed near south-facing windows and plants needing partial sun should be near east- or west-facing windows. Homeowners should avoid placing their containers in spots that experience wintertime drafts, like by doors.
“One must remember that the outdoor environment of summertime is very different compared to the heated indoor environment of winter,” Harold Taylor, a section gardener at Longwood Gardens told Mother Nature Network.
For containers that are too big to bring indoors, or if homeowners are reluctant to have their plants inside for whatever reason, these can be prepped to survive winter’s freezing temperatures and gusty winds.
Keep in mind some plants will not be hardy enough to survive winter conditions so let your customers know that in order to overwinter a perennial or shrub in a container outside, it needs to be two zones hardier than the zone they live in.
One of the other challenges aside from more exposed roots, is soil moisture. Overwatering can cause the container to break from expansion as ice forms, but dry soil allows frost to penetrate deeper in the air spaces.
Containers should be clustered with the smallest in the center in a protected area, such as an overhang or near a south facing wall. They can also be covered with materials like leaf litter and mulch to help insulate the plants.
In open areas, creating a burlap screen as a windbreak can provide protection for woody plants and other plants that are susceptible to sunscald. The most extreme method available for outdoor containers is trenching, which is where the plant, pot and all, are laid down and covered with soil and mulch for the winter.