Mandevilla is a tropical vine that puts on a spectacular show of trumpet-shaped blooms all summer, then dies at the first hard freeze, which leads many gardeners to toss it out every fall and rebuy each spring. You do not have to. Learning to overwinter mandevilla in garage spaces lets you keep the same plant alive year after year by forcing it into dormancy through the cold months. Done right, your vine survives the winter resting in a cool, dim garage and bursts back to life when warm weather returns. Here is the full process.
Why the Garage Method Works
Mandevilla cannot survive freezing temperatures, but it also does not need to keep growing through winter. The garage method takes advantage of dormancy, a natural rest period. Instead of fighting to keep the plant blooming indoors with inadequate light, you let it go semi-dormant in a cool, protected space where it needs very little care until spring.
An attached, unheated garage that stays above freezing is ideal because it holds a steady cool temperature, shields the plant from frost, and provides the dim, low-activity environment dormancy requires.
Timing: Bring It In Before Frost
The most important rule is to move the plant indoors before the first frost. Mandevilla is damaged by temperatures below about 45 to 50 degrees Fahrenheit and will be killed by a hard freeze. Watch your local forecast in fall and bring the plant in once nights start dropping into the low 50s.
Do not wait for the first frost warning and scramble. Move it ahead of the cold so it transitions gently rather than getting shocked by a sudden chill.
Prep the Plant Before Storing
A little preparation prevents pests and disease from spreading in storage.
- Prune it back: cut the vine back by roughly one-third to one-half to make it manageable and reduce the foliage it has to support while dormant.
- Inspect for pests: check leaves and stems for aphids, spider mites, and whiteflies. Treat with insecticidal soap before bringing it inside so you do not carry an infestation into the garage.
- Clean the pot: remove dead leaves and debris from the soil surface.
- Bring potted plants in whole: if it is in the ground, dig it up and pot it before the move.
Setting Up in the Garage
Place the plant in a spot that stays cool but never freezes, ideally between about 50 and 60 degrees Fahrenheit. A garage that hovers around 45 to 60 degrees is perfect. Some indirect light from a window is a bonus but not essential during dormancy, since the plant is resting rather than actively growing. A dim corner is fine.
If your garage gets dangerously cold during deep freezes, move the plant closer to the interior wall it shares with the house, wrap the pot to insulate the roots, or relocate it temporarily to a basement.
Watering During Dormancy
This is where most people go wrong. A dormant mandevilla needs very little water. Water just enough to keep the roots from completely drying out, roughly once every three to four weeks, giving only a small amount each time.
Overwatering a dormant plant in a cool space leads to root rot because the plant is not actively drinking. Let the soil stay on the dry side. The plant will likely drop most or all of its leaves, which is completely normal during dormancy and not a sign that it has died.
The Houseplant Alternative
If you would rather keep the plant green and lightly growing instead of fully dormant, you can overwinter mandevilla as a houseplant. Place it by a bright, sunny south-facing window indoors, keep it warm, and water moderately. It will not bloom much in low winter light, and it may get a bit leggy, but it stays alive and active. The garage dormancy method is lower maintenance, while the houseplant route keeps it looking lively if you have a sunny window to spare.
Reviving It in Spring
As the weather warms, gradually wake the plant up. When nighttime temperatures reliably stay above 50 degrees Fahrenheit and all danger of frost has passed, follow these steps:
- Move the plant to a brighter, warmer spot indoors first to break dormancy.
- Resume regular watering as new growth appears, keeping soil evenly moist.
- Begin feeding with a balanced or bloom-boosting fertilizer.
- Harden it off by setting it outside for increasing periods over a week or two so it adjusts to outdoor conditions.
- Once nights are consistently warm, return it to its sunny outdoor home.
Troubleshooting
Total leaf drop in winter is normal, so do not panic. If stems turn mushy or black, you likely overwatered, so cut back on water and improve airflow. If the plant looks shriveled and bone-dry, give it a modest drink. To check whether a dormant-looking vine is still alive, scratch a stem lightly with your nail. Green underneath means it is alive and will rebound in spring.
Taking Cuttings as Backup Insurance
If you are worried about losing a mature plant over winter, hedge your bet with cuttings. In late summer, snip a few four to six inch stem tips, remove the lower leaves, dip the cut ends in rooting hormone, and pot them in moist potting mix. Kept warm and bright indoors, they often root within a few weeks, giving you young plants to grow on even if the parent struggles. It is also a free way to multiply your mandevilla for more containers next season.
Common Garage Overwintering Mistakes
A few avoidable errors trip people up. Waiting too long to bring the plant in and letting it catch a frost is the most damaging. Overwatering during dormancy is a close second, rotting the roots in cool conditions. Letting the garage drop below freezing during a cold snap can kill the plant outright, so monitor the temperature during deep cold. Finally, skipping the pest check before storage lets aphids or mites multiply unchecked in the protected indoor space, leaving you a heavily infested plant by spring.
Final Thoughts
To overwinter mandevilla in the garage, bring it in before frost, prune and de-pest it, and let it rest in a cool, dim space above freezing with only occasional sips of water. Treat the leaf drop as normal dormancy, then gradually wake and harden the plant off in spring. With this simple routine you can keep one mandevilla blooming summer after summer instead of buying a new one every year.
