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Everything You Need to Know About Garden Mums


March 24, 2021
Category: Growing Tips

Are you thinking about adding Garden Mums to your commercial greenhouse? These traditional plants are easy to grow and even easier to sell since customers look for mums in autumn, whether you’re stocking them or not.

Use this thorough guide to plan for success in the timing and care of your Belgian Mum rooted liners. We’ll walk you through each major consideration, to prepare you for everything — ordering, transplanting, growing, and then, finally, offering an excellent finished product to your customers. 

The Difference Between Garden Mums and Pot Mums

There are two major types of mums widely available. Pot Mums (Chrysanthemum Morifolium, or Florist’s Mums) are annuals outdoors and typically grown as houseplants or office plants and given as gifts. They can bloom all year in a cycle.

Garden Mums are the standard mum sold and displayed in fall. With proper care, they can be grown as perennials in zones 5-9. They are photoperiodic, blooming only while daylight is at a certain length. 

How to plan when to get your garden mums

You’ll need to consider two elements to determine when to order and receive your mums. First, when you want to have the plants begin budding so you can sell them. Second, what pot size(s) you’ll be using, and how much time you’ll need for vegetative growth prior to budding.

When will you sell the plants?

If you want to begin selling mums in September, you’ll want to order mums that begin budding around that time to offer the best display and longest bloom time to your customers. 

Since Garden Mums are photoperiodic, you need to be aware of any light that is reaching your plants. Mums need more daytime light and shorter nights for vegetative growth and less daytime light with longer nights to initiate bud growth. Be aware that any light, whether natural or artificial, can affect growth. Mums need to be grown in full sun, not shade.

Plants will bloom at their regular time under natural day regardless of vegetative growth. This means that a mum that blooms in mid-September will bloom then whether it is an inch tall or three feet tall. Be sure to plan enough time for vegetative growth prior to budding and choose varieties that begin budding around when you’ll display them for sale. 

You can use a controlled growth program with black cloth and artificial lights to adjust and control plant and bud growth and grow out of season. You can also use black cloth or grow lights to supplement a natural day approach for appropriate amounts of light off-season or to help your mums bud sooner. However, a natural day approach to growing mums is simpler than one that involves black cloth and can easily be implemented if you order and grow your plants at the right time. 

In the North, plan for varieties that bud earlier, before frost, or plan to use black cloth to control flowering and plant your liners with the intended budding date in mind. Southern bloom time will be later. You may need to shift an early October mum to late September in colder climates.

This page will show you varieties by bloom time, so you can choose mums that are appropriate for your needs. The bloom time information available is for southern crops. For northern crop time information, contact us directly, or visit Gediflora’s website. Get more tips and tricks on ordering your Belgian Mum Rooted Cuttings here.

What size pot will you be using?

Pot size will determine how many weeks you’ll need to plan for your mums to have an appropriate canopy size. The umbrella of flowers at the top of the plant should be twice the size of the pot. For example, an 8-inch mum pan should have a 16-inch canopy. 

With some fluctuation based on heat and feed rate, mums grow at a rate of about 1.5 inches a week. Plan for an extra week to account for fluctuations.  An 8-inch mum pan takes 12 weeks to finish; a 9-inch mum pan takes 14 weeks to finish. 

Once you know how many weeks you’ll need to finish your mum rooted liners for the appropriate pan size and when your mums will begin blooming, you can calculate when to have your mums shipped. 

To finish 9-inch mum pans for blooming in mid-September, you’ll need to plant your liners the last week in May to allow for 14 weeks of vegetative growth, with a week for wiggle room to allow for minor heat and feed rate shifts. Book your mums to arrive a week before you need to plant them to make up for shipment or shipping delays. 

Pest Problems

While deer and rabbits aren’t typically attracted to garden mums, you may see some insect activity from Aphids, Caterpillars, Leafminers, Mites, and Thrips. Caterpillars and Leafminers tend to cause the most damage to mums, but which insect problem affects your plants will depend somewhat on how common and widespread these pests are in your area. 

Pay close attention to your plants to look for signs of infestation. A preventative spray for Leafminers can prevent serious damage to your plants. You may choose to spray preventatively or at the first sign of pests for other potential pests. Use insecticides on a rotation.

The breeder recommends that we use the following sprays to treat mums for each potential pest.

  • Aphids: Marathon II, Safari, Flagship
  • Caterpillars: DiPpel, Conserve
  • Leafminers: Citation, Avid, Safari, Pedestal, TriStar
  • Mites: Avid, Floramite, Sanmite, Kontos, Akari, Pylon, TetraSan
  • Thrips: Mesurol, Conserve, Avid, Pylon, Nemasys, Nemashield, Overture

Rotating insecticides addresses the pest lifecycle and prevents pests from developing resistance to one spray used over and over. 

Plant Problems

You may see some disease problems with mums, primarily Fusarium and Bacterial Leaf Spot. Pay close attention to the stems and limbs to look for discoloration or dying stems. In cloudy, rainy weather or with excessive humidity, drench your plants with fungicide at their base as a preventative measure. Otherwise, you can apply fungicide at the first signs of disease. 

The breeder recommends the following fungicides to combat the most common diseases seen in mums.

  • Bacterial Leaf Spot: Camelot, Kocide, Cease, Python 27
  • Fusarium: Medallion, Heritage, Chlorothalonil, Terraguard, Pageant
  • Phytophthora: Aliette, Segway, Stature, Subdue Maxx
  • Pythium: Subdue MAXX, Segway, Truban, Terrazole
  • Rhizoctonia: Medallion, Heritage, 3336
  • Rust: Chlorothalonil, Heritage, Protect, Pageant, Strike, Dithane 

Check your product labels for specific application instructions, and keep in mind that a preventative rotation of fungicide drench can preserve the roots, stems, and display quality of your crop. 

Irrigation Options

When to water

Watering evenly and consistently in the first few weeks after planting your rooted cuttings is a key to helping your plants develop healthy root systems. Water at the base of each plant early in the morning, maintaining even moisture in the soil for those first weeks. 

Since these plants grow primarily in the morning sun, early morning nutrition to feed that growth is important. Watering early in the day can also help prevent root rot and fungal infections, as the soil dries throughout the day, rather than keeping roots sitting in soggy soil overnight. 

How much to water

Be sure your pots have good drainage to allow extra water or feed to exit the pot rather than putting your plants at risk for root rot. Use well-draining soil to plant your rooted liners. 

As the summer progresses and plants grow, you may notice some wilting in the afternoon after the heat of the day. For slight wilting, the plants are better off dry overnight rather than too wet; water them thoroughly the next morning. For plants that are dry early in the afternoon and showing signs of wilting, a second watering will be necessary. We recommend using only clear water without fertilizer for a second watering in the afternoon. 

How to water garden mums

You have a few options for watering small to large crops of mums for your commercial greenhouse. 

Overhead Watering

This method employs sprinklers or a hose to water plants from above, mechanically or manually. While it is easy and cheap to use and requires limited setup, we don’t recommend overhead watering for commercial greenhouses. It wastes a lot of water and fertilizer if you use sprinklers and is extremely laborious if you use a hose. It can damage blooms later on, and wet foliage can grow and nurture fungus, promoting bacterial leaf spot and other fungal diseases. 

Drip Tape

This method uses a flat drip line and connectors to bring water and fertilizer to plant bases; it uses evenly spaced holes to emit water. While it is more expensive than overhead watering, it is cheaper than the higher-quality drip tubes. You can automate your irrigation with your drip tape system and avoid wasting any water or fertilizer on the ground. It also waters at the base of each plant, keeping leaves and blooms dry to prevent damage and disease. 

This cheaper drip irrigation system is made to be used for only one year and then replaced. You may consider investing in more expensive drip tubes for long-term use. You can also face your drip line stretching and constricting water flow in the heat of summer, moving the emitter locations from outside of your pots. 

This system is more time consuming to set up than overhead watering, but with great efficiency benefits in water, fertilizer, and time use. 

Drip Tubes

This method is the best of the three if you have the money to invest in setting it up. Drip tubes are similar to drip tape, but of higher quality material intended to be used permanently. Once established, the system can be used to distribute water and fertilizer to multiple crops throughout the year without waste. You can automate irrigation and water at the base to avoid damage or fungal disease. 

While this system is expensive to install, an established commercial greenhouse would do well to consider the ongoing efficiency in water, fertilizer, and time that will result for years to come. 

Fertilizer Questions

The best way to fertilize your mums is in four stages without slow-release fertilizer. The more control you have over the fertilizing process, the better chance you have of growing superior mums. 

Slow Release (Osmocote) 

We have moved away from using slow-release fertilizer for two reasons. Sometimes this fertilizer releases too quickly and damages root systems. This problem especially occurs during the hot months of summer. You don’t have control over how much fertilizer your plants receive at given points of plant development. This lack of control makes following the four stages of fertilization a much better option for growing mums. 

If you absolutely must use slow-release fertilizer, use a 3-4 month release type at 6-12 pounds per cubic yard in your soil, or as a top dressing. A newer brand is less likely to release solely on soil temp. Keep up with soil tests to be sure you are maintaining proper pH and EC levels.

Four Stages of Fertilization

Proper fertilization is the key to growing superior mums. Ideally, you’ll fertilize in four stages. The more controlled, precise, and attentive you are, the better you’ll be able to develop a fertilizing program that works well for your climate and rooted cuttings. Regularly test your soil to check on whether your fertilizer regimen is providing the nutrients your plants need. We’ve found this four-stage feed program to work best for mums.

Root Development

Immediately after transplanting your rooted liners, feed with 300 ppm of 20-20-20 or a similar fertilizer that is rich in phosphor and ammonium-based nitrogen. Keep your plant evenly watered for the first couple of weeks, and don’t let it dry out at all to stay on schedule.

Vegetative Growth

At the beginning of week 3, feed with 250 ppm of 20-10-20 during the morning watering. If your plants need a second watering in the early afternoon, use plain water without fertilizer. Water a second time sparingly, only if you see dry soil and wilting early in the afternoon.

Generative Growth (Bud Development)

When you begin to see bud development, continue at 250 ppm of 15-5-30 fertilizer. This higher potassium content will support flower production.

First Color (Flower Development)

When you see first color, stop using fertilizer and feed with straight water. This helps to create more vivid color in the blooms. 

General Growing Pointers for Garden Mums

Planting

Plant only one plug per 8-inch or 9-inch pot. Be sure to plant rooted cuttings in the center of the pot to avoid lopsided pots. Use 1-3 plugs per 10-inch pot. Plant 3 plugs per 12-inch pot.

One plug will take longer to grow to the proper umbrella width before blooming in a 10-inch pot, so if you’re short on time, plant additional plugs to fill the container with vegetative growth more quickly. Don’t plant additional plugs in 8-inch or 9-inch containers. Instead, plan ahead for enough time for vegetative growth or use black cloth to control daylength and keep your plants from blooming too early. 

Lower the canopy closer to the pot by planting rooted cuttings deep, burying the first 2-3 leaves at the bottom of the plant. 

When you transplant, you may choose to do a foliar spray with Florel. This won’t increase branching or vegetative growth, but can prevent premature budding. Repeat the spray treatment every two weeks if you desire. Be sure to stop the treatment at least 8 weeks before you intend to sell your plants. Note that Florel will only prevent new bud formation and will not stop existing buds from continuing to develop. 

Pinching & PGRs

Belgian mums need neither pinching nor growth regulators. Provide ample time for vegetative growth and carefully center rooted cuttings in your pot to create the best crop. 

If you must pinch your plants, remove a ½ inch or less, as any hard pinch or pinch after mid-July could delay flowering.

Observing proper crop time is the best way to grow Garden Mums. You can use PGRs to delay growth if things don’t go according to plan. Slow growth with B-9 at 2500-5000 ppm. Stop growth with a Bonzi drench at 2-3 ppm. Apply growth regulators no later than 2 weeks prior to first color, as late application will delay flowering. 

Spacing

Provide proper spacing for your pots to avoid stovepipe plants and to allow for adequate airflow. Approximately double the size of your pot to find the minimum spacing requirement between containers. Add 2 inches for preferred spacing. One plant’s foliage should never touch the plant beside it. Check this chart or calculate for your unique pot size.

  • 6 Inch Pots: 12” minimum – 14”+ preferred
  • 8 Inch Pots: 16” minimum – 18”+ preferred
  • 10 Inch Pots: 20” minimum – 22”+ preferred
  • 12 Inch Pots: 24” minimum – 26”+ preferred

Location 

Put your pots outside in full sun. Shade will force mums to bloom early, turn yellow, and struggle. They need direct full-day sunlight.

Belgian Mums bloom for about three weeks from the time buds first begin to open up to the time all blooms are spent. They’ll have about a half week of pre-flower buds and 1.5-2 weeks of full flower blooming. Plan sales accordingly and consider staggering bloom periods by stocking several varieties that bloom at different times. 

Offer Belgian Garden Mums to customers who want a traditional autumn flower to decorate the front porch or garden, as well as to customers who are interested in a perennial plant to add a few weeks of fall color to a border or container. With proper care, mums can be overwintered in zones 5-9. They are a lovely, traditional addition to any customer’s outdoor fall decor and easy to sell as such.