Perennials & Shrubs

Will my mums come back next year?

The short answer: garden mums can come back in Minnesota, but a mum planted in late September usually doesn't. It spent its whole life making flowers instead of roots, and it goes into winter with a root ball the size of its pot. Plant earlier, leave the stems on, and mulch after the ground freezes, and your odds go way up.

Garden mums vs. florist mums

The potted mums in foil wrap at the grocery store are florist mums, bred for indoor color. They aren't winter-hardy anywhere cold; enjoy them and compost them. Garden mums (also sold as hardy mums) are the round, cushion-shaped plants you see outside at garden centers in fall. They're rated to zone 4 or 5, and some varieties, especially the University of Minnesota introductions, are bred specifically for our winters.

Why most fall mums don't come back

• They're planted too late. A mum needs about six weeks of root growth before the ground freezes. One planted in October barely roots at all.
• They get cut back. The old stems help catch snow and protect the crown. Mums cut to the ground in fall die more often.
• They sit in wet soil. Mums rot in soggy, poorly drained spots far more often than they freeze.
• They stay in the pot. A mum left in its pot on the step has no protection at all; the whole root ball freezes solid.

How to give yours the best chance

• Plant by early September if you can, in full sun and well-drained soil. Earlier is better; mums planted in spring come back most reliably of all.
• Plant it a little deep: about an inch lower than it sat in the pot, and loosen the roots.
• Water through fall until the ground freezes.
• Leave the stems on all winter. Our fall cleanup guide explains why.
• Mulch after the ground freezes with 3–4″ of straw or leaves over the crown, and pull it back in April.

Next spring

Surviving mums send up new shoots from the base in late April or May. Cut the old dead stems off then. Pinch the new growth back by half every few weeks until early July for a bushy plant covered in buds instead of a tall, floppy one. Stop pinching after the Fourth of July, or it won't bloom before frost.