Many folks assume the fall chrysanthemums normally seen in garden centers are hardy perennials and I’m here to tell you (unfortunately) that is just ain’t so.
Are Mums Annual or Perennial?
The fall mum normally found on benches is a tender perennial and in a USDA zone 4, you’ll rarely get it to successfully overwinter two seasons in a row. Having said that, your garden may have a warm microclimate next to a house or special spot that allows you success with growing fall mums but on average, they won’t. (Note you can find other articles about perennial flowers (here)
There are hardy varieties / species and they are listed below along with their hardiness ratings. Normally these are found on the perennial benches of garden centers.
The trick to growing fall mums and getting them to flower heavily is to treat them in a specific manner.
- They like full hot sunshine.
- Give them shade and they get tall and leggy.
- They like regular and deep waterings all summer long. Figure soaking them at least twice a week.
- They like to be fed. Feed with compost in the early spring and then give a booster of fish emulsion every two weeks to really pump them along.
How Many Times Does A Mum Bloom?
The answer to this question is generally once a year. The blooms are triggered by a reduction in light levels and this happens naturally in the fall.
One of the things I should point out about growing fall mums is that the spring is the critical time to succeed with this plant. Dig the “babies” or offsets off the mother plant when they’re about 4-6 inches tall (late spring) Don’t worry about trying to save the mother plant – the odds are it’s not going to survive the winter in very good shape anyway. Get those babies! If the mother did survive in my gardens, I’d dig it up and compost it anyway. The best flowering seemed to come from those offsets.
It is also a very easy plant to propagate from cuttings. And a cutting taken in very early spring will grow out to a full blooming plant by fall if you grow them properly
Do not mulch this plant over top of the plant! It will rot out. While it likes constant moisture during the summer months, (this is not a dryland plant) it absolutely hates it during the winter
Can I Get My Indoor Mum To Rebloom Outside?
If you get a fully grown and flowering mum for Mother’s Day, then yes you can get it to rebloom in the same year. Cut it back as below (about one third in the case of potted mums in 6-inch pots) and replant in garden after danger of frost has disappeared. It will rebloom in the fall.
Will It Survive The Winter? Probably not but hope springs eternal so leave it and grow it as below in the section Double Duty From A Fall Mum.
How Big Do Mums Get
Well, that’s a “depends” kind of answer. If you prune them as I recommend in this article, they’re going to grow to “about” 12-18 inches (30-45 cm) and about 24 inches (60 cm) wide.
If you don’t prune them, they’ll tend to grow tall and leggy (falling over in a fall rain) and around 36 inches or 90 cm tall. See below “The Biggest Growing Trick”
The Biggest Growing Trick
Here’s the major trick in growing fall mums! Let them grow in the early spring and when they reach 12-18 inches tall, cut them back by half so they are only 6-9 inches tall. This will force the plant to bush out and produce more shoots. (more shoots equals more flowers)
Allow leaves on the bottom shoots. In other words, do not cut back so far as to remove all leaves.
If you don’t cut them back at 18 inches tall, they will continue to grow to 3 feet tall and produce flowers on top of the plant. A reduced number of flowers I note.
Double Duty From A Fall Mum
If you want to get double duty from the garden, allow the fall mum to overwinter in the garden where you’ve planted it. Assuming it survives do the following.
Dig it up in the spring. Divide off babies from the main mother plant to increase your fall display. Replant in the vegetable garden.
In the fall, move it back to the garden to fill in bare spots. And then allow it to overwinter there.
At this digging and moving time, you’ll see all the babies around the main plant.
These can be pulled off the plant and as long as they have a bit of root, they’ll grow into full mums by fall if treated well by keeping them watered.
I’ll often throw away the woody center in the spring (it’s often dead anyway) and only grow the surrounding babies into full flowering fall mums.
Mums can also be easily propagated in the spring from divisions and or tender tip cuttings.
Unsure how to take cuttings? Check out my Plant Propagation ebook
Hardier Fall Chrysanthemums
These are some of the tougher plants on the market.
The old style of mums such as
- Chrysanthemum x rubellum ‘Clara Curtis’ and
- Chrysanthemum ‘Mei-kyo’.
Chrysanthemums bred in Minnesota including:
- ‘Inca’, light bronze-orange, double button, low, early
- ‘Burnt Copper’, copper orange-bronze, double pompon, tall, midseason
- ‘Centennial Sun’ bright golden yellow, double decorative,medium height, early
- ‘Minnautumn’ reddish bronze, formal decorative, low, midseason
- ‘Minngopher’ crimson red, decorative, low, late
- ‘Minnruby’ ruby red, decorative,low, midseason
- ‘Snowscape’ white with purple tips,semi-double decorative, low, early
- ‘Mellow Moon’ cream, semi-incurved decorative, medium, midseason
- ‘Minnwhite’ white, decorative,low, early
- ‘Rose Blush’ mauve, decorative, low-medium, midseason
- ‘Rosy Glow’ deep rosy pink, decorative incurved, medium, midseason
- ‘Snowsota’ white with cream centers, pompon, low, midseason