The truth is, it depends. Most of us love to buy armloads of nursery-grown mums and asters each fall to decorate our drives, porches and patios. Then it gets cold, and we’re stuck with what to do with them before winter sets in. It seems wasteful to throw them all out. So inevitably, we tuck a few into the ground and hope for the best.
Sometimes we get lucky and they show up (finally!) in late spring…but more often not. So what gives?
In this article I’ll weigh the pros and cons of overwintering late bloomers. Some thrive in the garden and others don’t. In fact, many are bred just to get tossed. The trick is knowing which is which, along with a few tips that should significantly increase your chances for success.
Three common mistakes people make when trying to overwinter fall-bloomers:
- Planting too late
- Leaving the flowers on after planting in the ground
- Choosing a non-hardy variety
We’ve all done it. We buy on impulse, wait till the flowers turn brown and then figure we’ve nothing to lose by overwintering them. We hurriedly dig a hole, plop in the root ball, slosh with water, mulch, pray.
But next spring, nothing.
Okay maybe that’s a little harsh, but you know what I mean. We’ve all had failures. But it is possible to successfully overwinter at least some asters and mums from fall nursery pots. (No guarantees, of course!)
This year, why not try doing things a little differently?
Tips for Success
Transplant early. If you want a pot of asters or mums to survive the winter, get them in the ground as soon as possible. Don’t wait until they’ve turned brown and Halloween is here, or even Thanksgiving. Do it in September. Tease the root ball a bit, too. The roots need all the encouragement they can get to reach out before the ground freezes. Water regularly. No need to fertilize.
Remove the flowers. Really? Yes. The sooner you cut off the flowers, the faster the roots will establish. This is true of any transplant but it’s really important in the fall. A plant can’t flower and root at the same time and do both well, any more than a person can play the flute while bicycling. One or the other is bound to suffer! So favor the roots to let the plant establish.
If you just can’t bear to sacrifice perfectly good blooms, split the difference. Enjoy them for a week or two, then trim them back. Just don’t wait until they’re done. It’s brutal, sure. Still, don’t skip this step. It’s the price you pay for fall planting, but it can make the difference between success and failure.
Alternatively, you can always buy damaged or imperfect plants (sometimes at a discount) specifically for overwintering, since you’ll be cutting them back hard anyway. Save the perfect ones for the front porch. A pricier way to go, maybe, but definitely less upsetting.
Check for hardiness. Make sure you select a hardy variety. Plenty of mums won’t survive outside zones 7 or 8. Pots often have very little to no information so try to buy from a nursery or garden outlet where the staff is knowledgeable. Also, you can research varieties online before you shop. For example, mum Jolly Cheryl Red is hardy to zone 7, but Jolly Cheryl Pink is hardy to zone 6. Who’d have guessed that?
Mark your planting location. It’s best to leave any dead foliage on over winter, but if you do trim it all off, mark the spot you planted it. Mums and asters are notoriously slow to break dormancy in spring, leading us to think they’ve surely died. I’ve even tried planting spring flowers right on top of late-breaking mums because I didn’t see them trying to come up!
Be patient. If they’re going to emerge, it will be after everything else is up. The young shoots are often maroon or dark red, very hard to see against dark brown soil. If by the end of April there is still nothing, maybe they didn’t make it despite your best efforts. It happens.
Cut back mums in midsummer. Once they’re growing nicely for you, pinch or cut them back when they are about 8 inches tall, or when they show signs of budding up. Doing so will double the flower count and delay blooming until fall, when you want them to flower. If you forget and they bloom early, just know they won’t look like much in September and October. They may repeat bloom lightly, but they won’t be very full.
Asters vs. Mums I find asters not only overwinter better overall, they tend to live longer year over year. Asters can also handle a bit of light shade, whereas mums cannot. Mums really need a south-facing aspect to thrive. Luckily, neither are picky about soil.
I find that mums that overwinter for me (primarily certain yellows) put on a great show if they can face south in full sun. It really depends on the variety and your garden’s specific growing conditions (and the weather) as to which will do better. You’ll just have to experiment.
So don’t give up. Try these tips first. And be sure to ask the garden center which varieties they recommend as being the hardiest.
If you really don’t want to take your chances in fall, seek out the cultivars you want online and if at all possible, plant them in the spring. The trick to spring planting is finding the cultivars you want locally. Many garden centers don’t carry asters or mums in spring at all. If that’s the case in your area, you will just have to make fall work. Now you know how!
