No, a morning glory winter flower does not exist in most climates. Morning glories are warm-season annuals that thrive in summer heat and die at the first frost. If you live anywhere that gets cold winters, your morning glory vines will not survive once temperatures drop.
The morning glory bloom season runs from midsummer through early fall in most parts of the country. You plant seeds after the last spring frost, wait 75 to 120 days for the first flowers, and then enjoy blooms until cold weather shuts everything down. That gives you a solid window of color from July through September or October. Your zone and local frost dates set the exact end point.
I watched my morning glory vines go from full bloom to dead in less than 48 hours after our first October frost last year. One evening the vines were covered in purple flowers. The next morning, every leaf had turned black and the whole plant looked like somebody hit it with a blowtorch. That fast death caught me off guard even though I knew it was coming. You don't get a slow fade with these plants. Frost kills them on contact.
Morning glory frost tolerance is almost zero because these plants come from tropical regions. They can't handle temperatures below 45°F (7°C) for any stretch of time. The cell walls in their stems and leaves burst when ice crystals form inside. Even a light frost that barely touches 32°F (0°C) for an hour will wipe out your entire vine overnight. This is why you should never plant them too early in spring either.
The biology behind this cold weakness traces back to their tropical roots. Morning glories evolved in warm climates where frost never happens. They never developed the protective compounds that cold-hardy plants use to survive freezing. Your vine has no way to protect itself when the temperature drops below that critical threshold. I tried wrapping my vines in burlap one fall to see if I could get a few more weeks of blooms. The effort was a total waste of time because the first hard freeze killed everything inside the wrap anyway.
You can extend your morning glory bloom season a bit by planting seeds early indoors. Start them 6 to 8 weeks before your last frost date and move them outside when the soil warms up. This head start gives you flowers earlier in summer and more total weeks of blooms before cold weather arrives. Soak the seeds overnight in warm water first to help them sprout faster.
If you live in USDA zones 9 through 11, your situation is different. Morning glories can behave as perennials in these warm regions and may bloom for most of the year. Southern Florida, coastal California, and south Texas all have the heat these vines need year-round. You still need to protect them during rare freezes, but a simple frost cloth over the vines on cold nights does the job.
I have a friend in San Diego who grows morning glories year-round on her patio trellis. Her vines never die back and she gets flowers in January. The rest of us in cooler zones have to treat them as annuals and replant each spring. Save your seeds in fall, store them in a dry spot over winter, and you can start fresh every year without spending any money on new packets.
Morning glories are summer flowers through and through. If you want winter blooms, you need a different vine like jasmine or winter honeysuckle. But for those warm months, nothing beats the daily show of fresh morning glory flowers opening at sunrise. You can plan your garden so other plants fill the gap once your morning glory vines die back in fall. That way you always have something blooming in your yard no matter what time of year it is.
Read the full article: Morning Glory Flower Guide
