Best Practices for Growing Garden Mums and Pot Mums
February 7, 2024 
Green Valley Greenhouse grows 300,000 garden mums every year in Ramsey, MN. Photo: Green Valley Greenhouse
Chrysanthemums are a staple in the lives of consumers, who have been buying and gifting mums for decades, but also for the growers. Growers may specialize in different crops throughout the year, but in the summer, many turn to garden mums.
Some grow garden mums in addition to indoor pot mums, which are ideal gifts for holidays. Whatever your mum program is, growers are looking to refine their production practices.
Greenhouse Grower spoke with three operations from our Top 100 Growers list, including Henry Mast Greenhouses, Dan and Jerry’s Greenhouses, and Green Valley Greenhouse. Three growers share their best tips and recommendations on growing mums.
Best Practices for Garden Mums
Henry Mast Greenhouses sticks just over 1 million mum cuttings to produce its garden mum crop in Byron Center, MI, every year, according to Director of Growing John Davies. His team finds it best to direct-stick cuttings as much as possible because it is more economical. Henry Mast uses a standard 85/15 mix of peat and perlite as its growing media and is looking into wood blends as well.
“When planting mum liners, you don’t want to be shallow,” he says. “You want to be deep enough that you can hold that stem. As it grows, you don’t want it to wobble. Plant just below the soil surface.”
Head Grower Andrew Butler of Green Valley Greenhouse agrees, noting that his team plants deep enough for a solid anchor to the cutting but not deep enough to cover all of the leaves. Green Valley grows 300,000 garden mums per year in Ramsey, MN. With newer genetics in garden mums over the last 10 to 15 years, pinching is no longer required for commercial growers.
Spacing is critical with mums to help avoid diseases and ensure the proper shape.
“If they grow into each other, then they grow straight up. If you don’t space them adequately, you’ll have squares instead of a ball shape,” Davies says. “We’ll have plants pot tight until they are just about ready to touch, then we’ll space it. If it’s a 10-week or 12-week crop, you can grow it for six weeks then space it.”
Some growers prefer not to touch the mums again and choose to space them right away, he says, but it all depends on the facility and how they can best utilize their square footage.
“At the end of the day, it’s about producing a quality product while maximizing return per square foot,” Davies says.
Henry Mast Greenhouses uses various irrigation systems on garden mums, but Davies says growers should be careful early with flood floors. When mums are young, flood floors may make them too wet. Mums should develop a robust root system before flood floors are used, about three to four weeks after transplant.
“Irrigate early, heavy, and often. We don’t use water stress as a means of plant growth regulation at all,” Butler says. “We flirt with low night temperatures up here all summer long that can tend to push mums into premature budding. Keeping them actively growing and water-stress-free helps.”
To start off mums with plenty of feed, Davies initially uses a higher fertilization rate of 300 ppm. For most of the crop cycle though, he uses 125 ppm to 150 ppm with a basic 17-4-17 feed. Starting next year, he plans to incorporate a base rate of slow-release fertilizer as well. He says Henry Mast grows most crops pretty lean because more fertilizer is not usually necessary and can also lead to more plant growth regulators. However, incorporating slow-release fertilizer may be beneficial at retail and for the consumer.
Butler says mums should have constant liquid feed right up to colored buds. Hungry plants can be more susceptible to stress and early crown budding.
Best Practices for Pot Mums
Hamza Daour serves as the General Manager of De Jong Greenhouse in Pella, IA, which is owned by Dan and Jerry’s Greenhouses. His team grows indoor blooming mums throughout the year. They primarily target Valentine’s Day, Easter, and Mother’s Day for the mums to appear in retail stores. However, De Jong grows and sells 4-inch and 6-inch pot mums to floral shops and grocery stores year-round.
“With other cuttings, we only want the tip of the bottom to be covered in soil. With mums, we put them as deep as possible. It helps with growth control and stability to make the plant stronger in the later stages. We try to put the cutting all the way down, and only leave the tip out of the soil.”
He says De Jong uses the same growing media for all of their crops in 4-inch and 6-inch containers, which is a 70/30 mix of peat and HydraFiber. The soil drains well and has a high oxygen level. Growers also use a wetting agent to avoid a crust. Daour says to make sure there is a wetting agent in the growing media so the water penetrates it after it dries.
About three weeks after the cuttings are stuck, growers check to see if the roots have reached the edges of the pot. If the roots have developed, it’s time to pinch.
When thinking about spacing, Daour says the mums should not touch.
“If mums touch, that is where the problems start,” he says. “Be generous with your spacing to ensure enough light penetration around the pot and avoid the leaves touching each other and diseases starting.”
The mums are placed to allow space for their targeted size. For example, if mums are expected to grow to 6 inches long by 6 inches wide, those mums will be spaced 6 inches apart.
With indoor mums, Daour says it is important to watch your watering. He encourages growers to take some mums out of the pot before and after watering to see how much water the plant is absorbing.
“Indoor mums like to be moist. We do not want them to go dry,” he says. “You need a consistent watering habit to avoid stress. Don’t keep them too wet or too dry, or switch from really dry to really wet overnight. Be consistent and cautious with water.”
Daour’s growing team uses a combination of irrigation booms, capillary mats, and hand-watering. If you use a boom, you still need to check for consistency, he says, because sometimes plants watered with a boom dry out faster.
To properly fertilize the mums, they start out with a Nitrogen mix of 20-15-20 until pinching (around three or four weeks). Then they switch to a Cal-Mag mix of 15-5-15 so the mums will have strong, thick stems.
Subscribe to eNewsletter
