If you want a spectacular fall display, knowing when to plant mums in the ground is the most important step. Getting the timing right ensures your plants establish strong roots and produce the maximum number of blooms.
Many gardeners buy mums in full bloom in autumn and plant them then. While this gives instant color, it often leads to plants that don’t survive the winter. For mums that come back year after year, you need a different strategy. Let’s look at the best times to plant for both immediate and long-term success.
When Should You Plant Mums In The Ground
The optimal time to plant hardy garden mums is in the spring. This gives the plant an entire growing season to establish its root system before winter. A spring-planted mum has the strength to withstand cold temperatures and will return reliably as a perennial.
You can also plant in early fall, but you must do it at least six weeks before the first hard frost. This is the absolute minimum time needed for some root establishment. Planting during the summer is possible but requires diligent watering to combat heat stress.
Why Spring Planting is Best
Planting in spring is the secret for perennial mums. The warm soil and longer days encourage vigorous root growth. When you plant in spring, you are giving the mum a simple mission: grow roots first, flowers later.
- Establishes Roots: The plant focuses energy on building a deep, extensive root system instead of immediate blooming.
- Survives Winter: Strong roots anchor the plant and access deep soil moisture, making it resilient against freezing and thawing cycles.
- Produces More Stems: A well-established plant will send up more shoots in the following season, leading to a bushier plant with more flowers.
The Risk of Fall Planting
Fall-planted mums are often treat as annuals because they frequently die over winter. The plant is putting all its energy into blooming when you buy it, not into root growth. When frost arrives, the shallow roots are vulnerable to heaving out of the soil.
If you do plant in fall, choose plants with lots of tight buds rather than full blooms. Water them consistently until the ground freezes and apply a thick layer of mulch after the soil is cold to insulate the roots.
Understanding Your Growing Zone
Your local climate dictates your exact planting window. The USDA Plant Hardiness Zone Map is your best guide here.
- Zones 4-5: Plant in late spring, after the last frost date. Early fall planting is very risky.
- Zones 6-7: Ideal for spring planting. Early fall planting (by mid-September) can work with care.
- Zones 8-9: You can plant in spring or early fall. Late fall planting is sometimes possible here.
Step-by-Step Guide to Planting Mums
Follow these steps for the best results, regardless of the season you choose.
1. Choosing the Right Plant
Look for “garden mum” or “hardy mum” on the label. Avoid plants that are completely pot-bound with roots circling tightly. Healthly green foliage at the base is a good sign, even if the top is in full bloom.
2. Selecting the Perfect Spot
Mums need at least six hours of direct sunlight daily. Less sun leads to weak growth and fewer flowers. The site must have well-draining soil; mums hate wet, soggy roots.
3. Preparing the Soil
Mums thrive in rich, well-drained soil. Work 2 to 4 inches of compost or aged manure into the top 6-8 inches of your garden bed. This improves drainage and provides nutrients.
4. Planting Correctly
- Dig a hole twice as wide as the root ball and the same depth.
- Gently remove the mum from its pot and loosen the roots slightly.
- Place the plant in the hole, ensuring the top of the root ball is level with the soil surface.
- Backfill with soil and firm it gently around the base.
5. Watering and Initial Care
Water thoroughly immediately after planting. Continue to water regularly, keeping the soil consistently moist but not waterlogged for the first few weeks. A 2-inch layer of mulch around the base helps retain moisture and suppress weeds.
Essential Care for Optimal Blooms
Proper ongoing care is what turns a planted mum into a blooming superstar.
Pinching for Bushier Plants
This is the most important task for spring-planted mums. Pinching removes the growing tip, encouraging the plant to branch out.
- Start in late spring when shoots are about 6 inches tall.
- Use your fingers or pruners to remove about 1 inch of the tip of each stem.
- Repeat this process every 2-3 weeks until early July. Stop pinching after mid-July to allow flower buds to form.
Feeding Your Mums
Mums are moderate feeders. Apply a balanced, all-purpose fertilizer in early spring as new growth emerges. You can give them another light feeding in early summer, but avoid fertilizing after August, as this can promote tender new growth that will get damaged by frost.
Watering Wisely
Mums prefer consistent moisture. Water deeply at the base of the plant when the top inch of soil feels dry. Avoid overhead watering, which can promote foliar diseases. They are somewhat drought-tolerant once established but will produce the best blooms with regular water.
Winter Protection for Perennial Success
Even well-planted mums benefit from a little winter help. After the foliage has died back from a hard frost, you can cut the stems down to 2-3 inches above the ground. Do not cut them down to early, as the stems help insulate the crown.
Apply a loose, airy mulch like straw or shredded leaves after the ground has frozen. This prevents the freeze-thaw cycles that can heave plants out of the soil. Remove the mulch gradually in spring as new growth appears.
Common Problems and Solutions
Even with good care, issues can arise. Here’s how to handle them.
- Leggy Growth: This is caused by insufficient sunlight. Transplant to a sunnier location or prune nearby plants blocking the light.
- Few Blooms: Usually due to lack of sun, over-fertilizing with nitrogen, or not pinching back the stems in spring and early summer.
- Powdery Mildew: A fungal disease that looks like white powder on leaves. Improve air circulation, water at the base, and use a fungicide if needed.
- Root Rot: Caused by soggy soil. Ensure planting site has excellent drainage and avoid overwatering.
FAQ: Your Mum Planting Questions Answered
Can I plant potted mums in the fall?
Yes, but treat them primarily for instant color. For them to survive winter, plant as early in fall as possible, ensure excellent drainage, and mulch heavily after the ground is cold.
How do I get my mums to bloom in the fall?
Mums are short-day plants, meaning they naturally initiate buds as nights get longer in late summer. Stop pinching back stems by mid-July to allow bud formation. Ensure they get full sun and proper nutrients.
Should I cut back mums after they bloom?
It’s best to wait until after a hard frost has killed the foliage. Then, you can cut the stems down to 2-3 inches above ground level to tidy the garden and prepare for winter mulch.
Why didn’t my mums come back this year?
Common reasons include planting too late in fall, poor drainage leading to root rot, insufficient winter mulch in cold climates, or the plant was a non-hardy florist mum variety.
Can I divide my mums?
Absolutely. Dividing every 2-3 years in early spring keeps them healthy and vigorous. Dig up the clump, use a sharp spade to cut it into sections (each with roots and shoots), and replant immediately.
Timing is everything with mums. By choosing to plant in the spring, you invest in a future of reliable autumn color. Your patience will be rewarded with robust plants that return larger and more beautiful each year. Remember to pinch, water consistently, and provide winter protection, and your garden will be filled with brilliant mum blooms for seasons to come.