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Mum’s the Word Now in the North

© Mary Henry

I want to lay to rest an old wives' tale. The one I'm talking about is the belief that chrysanthemums are not hardy garden perennials in the North. It's not true. Planted at the right time, now, they can be a reliable player in your garden. As the backbone of the fall season, it helps not to have to replace them annually. Spring planting for most fall blooming perennials is a good idea here. They have time to establish strong, extensive root systems before they put energy into blooming. Then the fall frosts won't find them without resources for the winter.

Mums used to be almost worthless in Minnesota gardens because they did not always bloom before the frost got them for the season. Modern mums have been bred to be "day neutral", meaning they flower when they get big enough, not when the day lengths get shorter. Growers have also learned to produce small plants in flower early in spring so that we can find the colors and forms we want. We can plant them and begin the pinching process that will make them bushy and full of blooms in fall.

Pinching is to annuals and perennials what pruning is to trees and shrubs. Since their stems are not woody, it is often done with the fingers, though I prefer a small pair of scissors. There are two types of pinches: hard and soft. A hard pinch is like severe pruning, you take off up to half of the foliage. A soft pinch is removing the tips of the branches, taking the growing point and 1 or 2 immature leaves immediately below it. When you first plant the young mums, pinch them hard (pinch established mums when they are 8 to 10 inches high). Then, in late June or very early July, soft pinch the growing tips of each branch. Don't do it later or you will delay the development of the blooms. With these two pinches you will have plants with many "breaks", the horticultural industry term for branching. Since mums bloom at the ends of their branches, you will have many more flowers than if you had not done this. The plants will be more compact too.

Every fall I perk up my garden display by also planting several blooming mums in spaces left by fading annuals. I know that these plants most likely won't be back, but the beauty they give me costs me less than a dozen roses would and lasts longer. I had planted about ten last fall, and even with the mild El Nino winter, only 2 came back. By contrast, in May of 1995, I was given one rooted cutting of an experimental mum from the University. I planted it immediately and it has now developed into a large plant that I should have divided this spring, but haven't yet. Its first winter with me was especially severe - no problem.