If you are hunting for colorful blooms that last until frost, you ll find them in that fall favorite, the chrysanthemum. Lois Reau, general manager of Gardenland Nursery on Dorr Street, suggests looking for varieties with female names. Ginger is orange, Stephanie and Jennifer are yellow, Emily is a pale pink, Linda is white, and Monica is purple, she says. She has been growing chrysanthemums for about 30 years and says Bravo is her favorite. It is an early dark-red mum with a lot of secondary blooms.
There are garden mums, also known as florist mums. They have been forced into bloom and don t have much of a root system. You will find garden mums at the grocery store or the farmers market. They are great to add a pop of color to the dwindling blooms in your autumn garden, but won t make it past a hard frost.
There also are hardy mums, which will last year after year. Any mums can be considered hardy if you treat them as perennials rather than a quick-flowering annual.
If you keep them watered until frost, mulch them heavily over winter, then give them fertilizer in the spring, you can overwinter just about any kind of mum, Ms. Reau says. The biggest key is watering them until the ground freezes.
To tell the two types of mums apart, look for shoots called stolons. Florist or garden mums don t put out stolons because they have been on the fast track to growing blooms in the greenhouse. Hardy mums will send out stolons that actually bend or grow horizontally in the soil or on top of the ground. Strawberries and crabgrass do the same thing. This is one way the plant will continue to survive as it sends out roots to start a new plantlet. It can be tough to tell if the plant sends out stolons when it is in a pot. Pull the plant out of the pot and look at the roots, Ms. Reau says. Look for a lot of white root mass. If they were forced fast, they won t have a lot of root mass. You want to see equal top and bottom mass.
The best time to get a hardy mum established is in the spring. Mums are grown for their blooms, not foliage, so keep the stems short, and keep lots of small branches coming off the main stem.
Ms. Reau says, If they bloom in the spring when they come up and go weedy, they won t flower in the fall. Snipping off the new growth keeps them compact and producing side shoots; keep the stems no longer than six inches. This means you might have to pinch them back every two or three weeks through the spring and summer. Let them go after the 4th of July so they have plenty of time to set their flowers on the ends of the stems and get ready to bloom in the fall.
It may take your mums about six weeks to get a good root system established to get them through the winter.
To give your hardy mum the best chance at a long life, dig a hole twice the width of the pot and about four inches deeper than the pot. Fill the bottom of the hole with a few inches of fresh topsoil and make sure the top of the soil line on the plant is level with the ground. Now, fill in the rest of the hole with a mixture of your own soil and new topsoil. Give it lots of water and mulch to keep it moist.
Divide hardy mums every three years. Keep them fertilized until mid-summer; that is also the time to stop pinching them back. Protect them over the winter with a thick layer of mulch up and around the root system, then dig them out of the mulch in the spring.
Another way to protect them from a bitter winter is to dig them back up just before the hard frost and keep them in a protected spot near the house and out of the winter wind. Or just pull them out of the ground after the first hard frost and start all over next fall.