Why Are My Mums Turning Brown

If you’re asking “why are my mums turning brown,” you’re not alone. This is a very common issue that frustrates many gardeners, especially as fall arrives and we want those vibrant blooms to last. The browning can happen on the flowers, leaves, or stems, and each points to a different problem.

Don’t worry, though. In most cases, the cause is fixable once you know what to look for. This guide will walk you through all the common reasons, from watering mistakes to hidden pests, so you can diagnose and help your plants.

Browning mums are usually a sign of stress. The plant is telling you something isn’t quite right in its environment or care. The key is to look at where the browning is happening. Are the flower petals turning brown first? Or are the lower leaves wilting and changing color? Let’s break it down.

Watering Issues: Too Much or Too Little

This is the number one culprit. Chrysanthemums have specific water needs that change with the weather.

Overwatering (Wet Feet): Constantly soggy soil suffocates the roots. They can’t breathe and begin to rot. This root rot then shows up as yellowing leaves that turn brown and wilt, often starting at the base. The plant may look droopy even though the soil is wet.
Underwatering (Drought Stress): Mums in full bloom need consistent moisture. When they dry out, the leaves and flowers will wilt, crisp up, and turn brown from the edges inward. Potted mums are especially vulnerable because they dry out very fast.

How to Fix It: Check the soil before you water. Stick your finger about an inch deep. If it’s dry, water thoroughly until it runs out the drainage holes. If it’s still damp, wait a day. Always ensure your pots have excellent drainage.

Fungal Diseases That Cause Browning

Moist conditions can invite fungal diseases, which love to cause brown spots and patches.

Botrytis Blight (Gray Mold): This often starts as water-soaked spots on petals that quickly turn brown and mushy. You might see a fuzzy gray mold in humid conditions. It spreads fast in cool, wet weather.
Leaf Spot Diseases: Various fungi cause small brown, black, or purple spots on leaves. The spots may grow and cause the entire leaf to yellow and brown before it falls off.
Powdery Mildew: While it starts as white powder, severe cases can cause leaves to twist, turn brown, and die back.

How to Fix It: Remove and discard any badly affected leaves or flowers immediately. Improve air flow by not crowding plants. Water at the soil level, not overhead, to keep leaves dry. In severe cases, a fungicide may be needed.

Pest Problems Sucking the Life Out

Tiny insects can cause big browning problems by feeding on plant sap.

Aphids: These small green or black bugs cluster on new growth and undersides of leaves. Their feeding distorts growth and can lead to browning. They also secrete a sticky substance that can grow sooty mold.
Spider Mites: Almost invisible, they create fine webbing and cause leaves to look stippled or dusty before turning brown and brittle. They thrive in hot, dry conditions.
Leaf Miners: These larvae tunnel inside leaves, creating squiggly white lines that eventually turn brown and necrotic.

How to Fix It: Spray aphids and spider mites off with a strong stream of water. Insecticidal soap or neem oil are effective organic treatments. Check plants regularly, especially under the leaves.

Environmental and Cultural Stress

Sometimes, the place you’ve put your mums just isn’t right for them.

Lack of Sunlight: Mums need at least 6 hours of direct sun daily. In too much shade, they become weak, leggy, and more susceptible to disease that leads to browning.
Overcrowding: Plants packed to closely together trap humidity and reduce air circulation. This creates a perfect environment for fungal diseases to take hold.
Nutrient Deficiency: A lack of essential nutrients, like nitrogen or potassium, can cause leaf edges to turn brown or yellow. However, to much fertilizer can also burn roots and leaves.

Is It Just Natural Aging?

It’s important to know that some browning is completely normal. As individual mum flowers age, they will naturally fade and brown at the end of their bloom cycle. This usually starts at the center of the flower and moves outward.

If only the oldest blooms are browning while new buds are still opening, this is likely just the plant’s natural process. Simply snip off the spent flowers—a practice called deadheading—to keep the plant looking tidy and encourage more blooms.

Step-by-Step: Diagnosing Your Browning Mums

Look at the Pattern: Is browning on leaf tips, whole leaves, or just flowers? Are lower or upper leaves affected first?
Check the Soil: Is it bone dry, soggy, or just right? Don’t just look at the surface.
Inspect Closely: Turn leaves over. Look for tiny bugs, webbing, or unusual spots. Use a magnifying glass if you have one.
Consider the Weather: Has it been very rainy, humid, or unusually hot and dry? Have you had an early frost?
Review Your Care: When did you last water or fertilize? Are the plants in full sun?

Prevention and Long-Term Care for Healthy Mums

The best cure is always prevention. Here’s how to keep your mums green and blooming.

Plant in the Right Spot: Choose a location with well-draining soil and full morning sun. Good drainage is non-negotiable.
Water Wisely: Water deeply at the base of the plant, allowing the soil to dry slightly between waterings. A soaker hose is ideal.
Promote Air Flow: Space plants adequately when planting in the ground. For potted mums, don’t cramp to many in one area.
Fertilize Properly: Feed with a balanced fertilizer in early spring as growth starts, but stop once buds form to avoid burning flowers.
Mulch Moderately: A thin layer of mulch helps retain moisture and suppress weeds, but keep it away from the plant’s main stem to prevent rot.

FAQ: Quick Answers to Common Mum Questions

Q: Can I save my mums if they are already turning brown?
A: Yes, often you can. Trim away all the brown, damaged parts. Correct the watering issue, treat for pests if needed, and move the plant to a better location. The plant may put out new growth if the roots are still healthy.

Q: Should I cut the brown flowers off my mums?
A: Absolutely. This is called deadheading. It makes the plant look better and directs energy to producing new flowers instead of trying to support dying ones.

Q: Why are my potted mums dying so fast?
A: Potted mums are often root-bound and dry out incredibly quickly. They may need water daily in hot sun. Also, many are treated as temporary displays and are not always bred for long-term hardiness. Check if the pot is to small.

Q: Could frost cause my mums to turn brown?
A: Definitely. A hard frost will blacken and wilt flowers and leaves. If an early frost is forecast, covering your plants with a cloth or blanket overnight can offer some protection.

Q: How often should I really water my garden mums?
A: There’s no set schedule. It depends on temperature, sun, and soil. The finger test is your best guide—water when the top inch of soil is dry. Deep, infrequent watering is better than frequent sprinkles.

Figuring out why your mums are turning brown takes a little detective work, but it’s usually a simple fix. Start by checking your watering habits and inspecting the plant closely. Most of the time, with a few adjustments to their care, you can get your chrysanthemums back to health and enjoy their colorful show all season long.