When To Plant Mums In Minnesota

If you want your garden to glow with fall color, knowing when to plant mums in Minnesota is your first step to success. Our unique climate, with its early frosts and cold winters, demands perfect timing for these autumn favorites to thrive.

Garden mums, or chrysanthemums, are often treated as disposable seasonal decor. But with the right care and planting schedule, you can get them to survive our Minnesota winters and return bigger and better each year. This guide walks you through the simple steps.

There are two main planting times for mums in our state, and each serves a different purpose. Your goal determines your schedule.

For Fall Color (Treated as Annuals)

Most mums sold in garden centers in September are for instant fall color. For this, you can plant them as soon as you buy them in late summer or early fall. The key is to get them in the ground at least 6 weeks before your area’s first hard frost. This gives the roots a little time to establish before the ground freezes.

In northern Minnesota, aim for late July to mid-August.
In central Minnesota, aim for early to late August.
In southern Minnesota, you can plant into early September.

Remember, these plants are focused on blooming, not root growth. They often won’t survive the winter planted this late.

For Hardy Perennials (The Overwintering Strategy)

To grow mums as true perennials that come back, you need a different approach. The best time to plant is in the spring. This gives the plant a full growing season to develop a strong, deep root system that can withstand freezing temps.

Plant after all danger of frost has passed, typically from mid-May to early June.
Spring-planted mums will have time to get established, and you should pinch them back through early summer to encourage bushy growth and fall blooms.

You can also plant hardy mum varieties in very early fall, no later than mid-September, but spring is vastly more reliable for survival.

Understanding Your Minnesota Frost Dates

Your local frost dates are your best gardening calendar. The average first fall frost in Minnesota ranges from early September in the north to early October in the south. Planting in spring aligns with warming soil, not just air temperature, which is crucial for root development.

Why Fall-Planted Mums Often Fail

Nursery mums in fall are in full bloom, directing energy to flowers, not roots. When planted just weeks before the ground freezes, they simply don’t have time to anchor themselves. A shallow root system heaves right out of the frozen soil during winter’s freeze-thaw cycles, a common problem here.

Choosing the Right Mum Variety

Not all mums are created equal for Minnesota winters. Always look for labels that say “hardy,” “garden mum,” or specific series known for cold tolerance.

Good choices include the ‘Minn’ series (like ‘Minnruby’ or ‘Minned’), ‘My Favorite’ series, ‘Sheffield’, and ‘Clara Curtis’.
Ask at local, independent garden centers—they often stock varieties proven in our climate.

Step-by-Step Planting Guide

Follow these steps for the best results, whether planting in spring or fall.

Pick the Right Spot: Mums need full sun. That means at least 6 hours of direct sunlight daily. Less sun leads to weak growth and fewer flowers.
Prepare the Soil: They prefer well-drained soil. Amend heavy clay Minnesota soil with compost or peat moss to improve drainage. Mums like slightly acidic to neutral pH.
Dig the Hole: Make it twice as wide as the root ball but no deeper. Loosen the soil around the hole to help roots spread easily.
Plant Properly: Place the plant in the hole, ensuring the top of the root ball is level with the soil surface. Backfill with your amended soil and gently firm it down.
Water Thoroughly: Give them a deep drink right after planting to settle the soil and eliminate air pockets.
Mulch Smartly: Apply 2-3 inches of mulch (like shredded bark) around the plant. This keeps soil moist, suppresses weeds, and insulates roots. Keep mulch a few inches away from the stems to prevent rot.

Essential Care Through the Seasons

Caring for mums is straightforward if you follow a simple calender.

Spring Care

As new growth emerges in late April or May, clean up any dead foliage from last year.
Once shoots are 4-6 inches tall, pinch off the top inch. Repeat this pinching every 2-3 weeks until early July. This forces branching for a fuller, sturdier plant with more blooms.
Apply a balanced, slow-release fertilizer in late spring.

Summer Care

Water deeply during dry spells, aiming for about 1 inch per week. Avoid overhead watering to prevent foliar diseases. Continue your pinching schedule until the July 4th holiday, then stop to allow flower buds to form.

Fall and Winter Care

Enjoy the bloom show! To improve winter hardiness, do not cut back the dead stems in the fall. The standing foliage helps trap insulating snow and protects the crown. After the ground is frozen in late November, you can add a few more inches of loose mulch (like straw) over the plant for extra protection. Remove this extra mulch in early spring.

Troubleshooting Common Problems

Even with good care, issues can pop up. Here’s how to handle them.

Leggy Growth: This means not enough sun or not pinching in spring. Move the plant next spring or be more diligent with pinching.
No Blooms: Usually caused by to much shade or pinching back to late in the summer. Ensure full sun and stop pinching by mid-July.
Winter Die-Off: If a hardy mum doesn’t return, it’s usually due to late planting, poor drainage, or a severe winter without snow cover. Spring planting is your best defense.
Pests: Watch for aphids or mites. A strong spray of water from the hose usually knocks them off. You can use insecticidal soap if needed.

FAQ: Your Minnesota Mum Questions Answered

Can I plant potted mums in the fall and have them come back?
It’s possible but not guaranteed. For the best chance, plant them as early in fall as you can find them (late August) and ensure excellent winter mulch. Treat it as an experiment—spring planting is far more reliable.

Should I cut back mums in the fall or spring?
In Minnesota, always wait until spring. The dead stems provide valuable winter protection for the crown of the plant.

How do I divide my mums?
Every 2-3 years in spring, as new growth appears, dig up the clump. Use a sharp knife or spade to divide it into smaller sections, each with roots and shoots. Replant the divisions right away. This keeps plants vigorous.

What’s the difference between garden mums and florist mums?
Florist mums are bred for perfect blooms in greenhouses and are not typically hardy. Garden mums are bred for outdoor hardiness and bushy habit. Always check the plant tag.

My mums bloomed to early. What happened?
Some varieties are naturally early bloomers. To delay bloom for fall, make sure you’re pinching back until early July. Also, avoid planting near streetlights or porch lights, as artificial light can disrupt their bloom cycle.

By following this Minnesota-specific advice, you can enjoy brilliant autumn color year after year. Timing is everything, and now you have the knowledge to work with our climate, not against it. With a little planning in the spring, those vibrant mum flowers can become a permanent part of your fall landscape.