Know it and grow it

George Bonnema

Luverne horticulturalist

The calendar says September so I’ll admit that we’ve moved out of summer even though I regret giving up the wonderful long days and opportunities of seeing progressive growth in flowers and vegetables ... now we are into the “wrap up” season.  If you are tired of deadheading your annuals, you can quit that job — although they will not look as appealing with dead flowers hanging there. Your choice.

 If your container gardens are looking tired, you can spruce them up by adding some colorful fall plants that will give a new burst of color. Keep in mind that some of these plants like the grasses, flowering kale and cabbage, asters, chard, and mums can handle frost. Others like celosia, sunflowers, peppers, coleus, etc. are extremely cold sensitive and will have to be protected if frost is a threat.

If you are selecting a potted mum to add to your outdoor décor, purchase a plant that is just beginning to show color. You can expect 2 to 3 weeks of bloom time, depending on the temperature and the stage of openness of the flowers, and of course depending on if you remember to keep the plant watered. These plants are grown in mass with automatic watering equipment that determines when the growing medium needs moisture. Once they leave the growing facility, it is people, not a sensor, that determines when to water ... that could mean trouble at the retailer or trouble at the customer’s home.

A large plant in a relatively small pot is going to dry out fast because of the quantity of plant in relation to the root system supporting it. That is augmented by warm temperature and wind speed. You need to keep the growing medium moist but not soggy wet ... my pet phrase is “moist like a cake is moist.”

The fall mum flowers do not have a lot of mass to the flower itself and that is the reason for the limited bloom time. That factor combined with water stress is something you need to be aware of in getting the most from your purchase. Also, most of these mums are considered annuals, meaning they most likely will not survive our Minnesota winters.

I was in the Twin Cities on Saturday, and the larger garden centers there were offering pots of “Minnesota Mums” that are much larger and fuller flowers and are varieties that are perennial — they should come back year after year.

I have the Mammoth mum series developed by the U of M in my gardens, and they have proven reliably hardy for a number of years and they will usually be in bloom for a minimum of 6 weeks.  Unfortunately, they are not a good candidate for pots because the mammoth part of their name refers to the size of the plant.


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