Chrysanthemums run the gamut, from bushy mounds covered with blossoms to stately, upright plants capped by one or just a few humongous blooms. Their colors and forms of flowers are equally variable.
Generally, you just buy the mums you like, plant them, then do nothing more than enjoy their blossoms. If you'd like to bring out the very best from any mum plant, however, pinch it a little here and there. A pinch is nothing more than pruning off with your thumb and index finger the last half-inch of stem.
And midsummer's the time to do it.
Mums are aware of summer's progress
No matter how you pinch-prune mums, keep in mind that these plants form flower buds in response to shortening days and cooler temperatures. The number of short days needed to induce flower buds depends on the variety of mum, with low, cushion mums needing the least number of days and large-flowered mums needing the most. Some of the larger mums flower so late that they must be grown in a greenhouse or in pots brought indoors in autumn.
Once a plant changes gears and starts entering the flowering mode, it responds differently to pruning than when it was vegetative (just growing stems and leaves).
Bushiness in a pinch
Out in the garden, a mum that is naturally bushy might look better if it is even more bushy. Promote bushiness by pinching each shoot beginning when it is six inches tall. Repeat this pinching each time shoots grow an additional six inches. Stop all this pinching no later that 90 days before the normal bloom date.
July is when most of these plants start to develop flower buds, and you don't want to remove those buds.
Pick your pinch for big blossoms
Growing mums for fewer but larger blossoms is a whole different ball game, and can be an exacting science. First, choose an appropriate variety; some mums will not make extra-large blossoms no matter what you do. Then remove all but one to three shoots on each plant, as well as any branches on those shoots. Stake each shoot separately to keep it rigidly upright.
The changeover to the flowering phase is gradual. If you don't pinch the tip of a stem at all as days shorten, the end of that stem becomes a flower bud. The flower stem itself stays relatively short and has strappy leaves rather than typical mum foliage. Side shoots grow out below this top bud, and somewhat later these shoots are also capped by flowers.
For a larger blossom, pinch off the side shoots so that all the plant's energy goes into flowers opening only on the main stems.
Alternatively, pinch out the tip of a main stem before it makes a flower bud. Three or so of the side shoots just below the tip will continue upward growth. Eventually, the plant will enter the flowering phase and the end of each shoot will be capped by a cluster of flower buds. These flower buds sit atop stems that are relatively long and do have the characteristic mum foliage – all of which is important for "show" mums.
Depending on how many and how large you want your blossoms, retain one or all of these shoots. For an extra large blossom, pinch out all but the top flower bud on each shoot that you left. Otherwise, let the ends of each retained shoot open into a spray, which is a large flower surrounded by smaller flowers, all blooming together.
The timing of the last pinch, as well as the number of stems and flowers to allow each plant, has been carefully calculated for the best show from a number of varieties.
Why all this precision? Because commercial and competition mum growers must eke the best from each of the plants. Just fooling around with mums can be fun for the rest of us gardeners.
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