Mum’s the Word: Growing Chrysanthemums
By Lois Hoffman
One of the most glorious things that happen when the air turns crisp at this time of year is the explosion of color. Certainly, the turning of the leaves and showy pumpkins are a big part of this but, also a big part, are the brilliantly colored chrysanthemums that characterize this season.
Chrysanthemums, or “mums” as they are often called, have always been my favorite flowers. Sorry, roses, but mums’ cheerfulness can’t help but bring a smile to your face. They are used in many of autumn’s colorful displays. Yet, they are perhaps the most misunderstood flower.
Are they annuals or perennials? There have been countless times that I have planted them in the flower gardens and sometimes they survive the winter and sometimes they don’t. What’s the deal here?
Well, there are two distinct varieties, namely florist mums and garden mums. They both are derived from the original plant, but today’s hybrids in both categories are results of hybridization between several species. The result is different types of mums that perform for two distinct purposes.
Photo by natalysavina/Adobe Stock
Florist mums are the large flower pots that you find in supermarkets at this time of year that have many possible bloom forms. They are grown in greenhouses and produce few, if any, underground runners which are necessary to survive cold temperatures. Garden mums, also called hardy mums, are perennials which do produce underground runners, which make them able to survive frigid winters and bloom the next season. The confusion comes because they both make great container plants.
Another factor that influences whether mums will bloom for more than one season is planting times. Fall planting lessens the chances of survival because roots don’t have time to establish themselves. When you plant them in the spring, it gives the plants more time to get established in the garden. Although planting earlier in the year improves the chances of overwintering and reblooming in the spring, it does entail more work. There is more mulching and pinching off buds to encourage compact growth.
Pinching back the new growth is one of the hardest things for me to wrap my head around. After all, plenty of buds and flowers is the goal, so why would you want to discard them? But that is the secret to the rounded domes of perfectly shaped mums that we see in stores. Each pinched stem will divide into two stems.
However, you don’t just start taking buds off at random. There is a method to this madness. When the plants reach a height of six inches, pinch back the tops of the stems one to two inches. Do this each time the plants get three to five inches of new growth up until July 4.
Once you have established plants, they need to be divided every couple of years. This is accomplished in spring after the last frost and new growth starts to appear. Pull up the entire plant and separate it into pieces with a clean and sharp spade or large knife. Replant the outer portions and discard the center. Three to five vigorous roots are enough to make a showy clump.
Mums planted in spring should be fertilized with 5-10-10 once or twice a month if you only want annuals. However, if you want them to come back year after year, use a high phosphorous fertilizer to stimulate root growth. After the first hard frost, mulch with straw or shredded hardwood about 4 inches deep around the entire plant. Leave the branches intact and only prune in the spring.
Chrysanthemums like sun, lots of sun to the tune of six hours a day. If they are deprived of this, they grow tall and spindly instead of round and full. Keep in mind that light is not the same as heat. They are not big fans of the scorching summer sun, thus if you are a spring planter, be sure and keep them well supplied with water during the hot days of July and August. The warmer the temperature, the more water the mums need. They typically like about an inch of water per week. If the bottom leaves start to turn brown or limp, water more often but be sure and water at the base of the plant instead of soaking the leaves which promotes some diseases.
Another way to ensure that mums return the following year is to plant native chrysanthemums. This means that if a variety has been native to your area, it will do better than a type that is not native to the conditions in a particular region.
Besides being showy and colorful, mums can help keep your garden free from insects. Many bugs don’t like them, so planted strategically among other plants will deter unwanted insects. Also, pyrethrum, a natural insect killer, is derived from the flowers of mums. Pyrethrum spray is made from the flowers of Chrysanthemum cinerariaefolium or Chrysanthemum roseum varieties.
You can even make your own insect spray by drying the flower heads and mixing with water and a little pinch of soap powder.
Armed with this knowledge about how to get mums to survive the Michigan winters, I am going to try my hand at them again this year. I am determined to have these vibrant flowers in my garden year after year. Mums are about the only flower where you get to choose whether it is an annual or perennial. How cool is that!
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