How Not to Kill Your Mums

Floral Mums
MargJohnsonVA/Twenty20

Come September in the U.S., mums are as ubiquitous as pumpkins the during fall harvest. You can find them everywhere and anywhere from nurseries to supermarkets to gas stations. However, once you get them home they are incredibly easy to kill. They dry out in a nanosecond and need to be watered at least once a day. After any repeated stress periods of drying out, they often just die. Take a look at five tips to keep your mums from shriveling.

how not to kill mums
Illustration: © The Spruce, 2018 

Repot It Upon Purchase

The single most important thing you can do to increase the longevity of your mums is to repot it as soon as you get it. Most mums are completely rootbound when you get them. The roots have taken up the entire pot, which makes it really hard for the soil to retain any water.

The best way to preserve your plant is to provide it with fresh soil. You can do this, by choosing a container that is a little bigger than the container your mums came in. Fill the bottom of the new pot with a good quality potting soil.

Carefully remove the mum from its nursery pot. Break up any roots you can, or simply rough them up by rubbing them. Put the plant in the new pot, making sure the surface of the soil rests at least an inch below the lip of the new pot. Make sure there is room for water to trickle down into the soil, instead of running off the sides and out of the pot.

Fill in the space around the plant's root ball with the potting soil; you want soil, not air surrounding the roots. Tamp down the soil gently. Give the pot a good watering—until it flows out of the bottom of the pot. You may need to add more soil after watering the first time. 

Give Mums Lots of Sun

Mums are sun-lovers, so make sure your pot gets, at the minimum, four hours of direct sun a day. As the fall days are short and the sun has already moved across the horizon since the summer, you may find that the places you get the most sun have moved. Where you once had full, unobstructed sun, a tree or building may now be blocking the light. You can use a sun calculator or roughly observe how long the sun is hitting your pot. You might be surprised.

Water, But Not Too Much

Mums do not like to get dry. When their leaves are drooping, which can happen ridiculously quickly, they are way too dry. Try to water them before they get to that point.

If you have not repotted your mum, which understandably most will not do, there are two ways to tell if it is dry. You can stick your finger, up to the second knuckle into the soil to see if it feels dry. However, sometimes this is not even possible because the plant is so rootbound and the soil is so hard.

You can also try picking up the pot. If it is light, water it, and water it deeply. Usually, you water a plant until the water pours out the bottom; however, with a potbound mum, it is possible that the water will go around the roots, down the sides of the pot and out the bottom without the plant getting much water.

Also, if you have let the plant dry out, soil contracts and the same thing can happen, leaving spaces along the sides of the pot for water to flow out without touching the soil.

To avoid this and rehydrate the dry soil, put the mum pot in a bucket of water with a few inches of water and leave it to soak for a few hours. Do not forget it, because the plant can drown if you do. You can also fully submerge the pot in a bucket of water to rehydrate the soil. Stick a skewer or a pencil in the soil at the top to make sure the water soaks in.

Deadhead Your Mum

Deadheading or removing dying flowers is one of those tedious garden chores that almost as soon as you finish it, you have to start over again. Deadheading mums are worth the trouble. The plants benefit greatly from it and will look much better when finished. Chances are great that they will last longer and may repeat bloom.

Choose a Strong Plant

Choosing the right plant is key to having it thrive. A plant that has repeatedly dried out will be stressed and not a good candidate. If you buy a mum at a supermarket or big box store, be particularly careful because they often are underwatered. It makes sense to ask the store what day they get their new shipments and try to buy a plant on the day they get there before they have had too many chances to be neglected. Look for plants where the leaves are deep green and healthy, not droopy. Find plants that have lots of buds and not too many blooms.

While some people try to overwinter their mums, it is very difficult to pull off successfully (unless you get a hardy mum). In most cases, it is best to treat it as an annual and pitch them onto the compost pile after they die off with the first frost.