The Greener View: Mums Not Blooming

Mums Not Blooming

Q: I planted nursery stock last year with the hopes of having blooming plants this fall. The plants are very healthy with lots of buds, but they have not opened. Also, the distribution of the buds is not uniform over the plants. Some sides show no buds while others do. The plants receive full sunlight from about 10 a.m. until dark. We are approaching freeze times, and I wonder if they will bloom before the freeze kills them. Any comments and suggestions would be much appreciated.

A: You mention that these mums are nursery stock. Do you happen to know which variety they are? Was there a tag specifying them, or just a generic "mums" tag? There are many varieties of mums, and they all bloom as the day length gets shorter, but some need a longer run of these shorter days, and some need fewer. If you can find the variety name, we could see how long they need cool weather and shorter days to bloom. Mums may be labeled as early or late-season; early season bloomers have a shorter critical night length compared to late-season types.

They also need cooler weather to help set flower buds. Many parts of the country are well above average and have not yet seen cool weather. Let's hope for a cooling off instead of a drastic drop all the way down to a freeze.

Is it possible that the sides of the plant that don't have buds were chewed on by rabbits? The pruning the rabbits do will slow the growth on that side of the plant, even if the damage was done months ago. Of course, recent chewing damage will remove flower buds. Any pruning of any kind after about the Fourth of July can slow the growth enough that there is not enough time for the plants to bloom. Mum plants that grow too tall and then flop over should be pruned in the spring so the plant will be shorter and stronger. The first pruning in the spring is when mum plants are about 8-10 inches tall. If you are planting mums in the spring, start the first pinch two weeks after planting. The second pinch is done around the summer solstice. This is the longest day of the year, and from then on, day length gets shorter, and the plants will naturally set buds. Many gardeners plan their final pinch on or about the Fourth of July.

Did the mums bloom earlier this spring? Sometimes cool spring weather and drying out can cause the plants to bloom. If they start to set spring flower buds, prune them off immediately and then keep the plant watered and fertilized, and it should bloom again at the right time. If the flower buds are left on in the spring, it probably won't bloom again in the fall.

Is the nonblooming side of the plant facing a yard light? Long periods of light at night can cause that side of the plant to think that the day length is still long and is not getting shorter.

Was fertilizer added to the soil near the plants? High-nitrogen fertilizer added to the soil on one side of the plant can cause that side to want to grow more leaves and not produce flowers as quickly as the side that didn't get the nitrogen fertilizer.

It is possible that the flowerpot with the mums had more than one type of mum in the pot. The mums in the pot would be given growing conditions to cause them to bloom, but in the ground, they may not be getting what they need.

Mums are often grown in a peatmoss soil mix. When planting them, it is best to remove some of the peatmoss to help force the roots to grow into the surrounding soil. If the plants were just plopped into the soil, the peatmoss could be holding more water on one side than the other. That could cause the roots on that side of the plant to grow at a different rate, which then affects the top of the plant.

What a list of potential problems. It is a wonder that any mums ever bloom.

Potential cures for next year include cooler fall weather, which is out of your control; no pruning after the Fourth of July, which may mean spraying them with rabbit repellent; and covering the plants each day a few hours before sunset to give the plants a longer night. This is all a huge hassle, and I would rather replace the mums than go through this work. Blocking any stray streetlights from reaching the plants might also be a hassle. Preventing them from flowering in the spring takes careful watching to notice the buds early. Proper watering and fertilizing may also help.

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Email questions to Jeff Rugg at info@greenerview.com. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.