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MASTER GARDENERS: What's (achoo!) blooming?

If you are one of the 30 percent of the population of the U.S., or 17 million adults and 6.6 million children, who suffer from seasonal allergies, this is your season. What is blooming now that leads to the misery many of us suffer.

There are plants in the landscape that nearly everyone knows about, some that have been given a bad rap, and those that you never would have guessed lead to the sniffles, itchy eyes and misery of “hay fever.”

This is undoubtedly the peak of the season here due to one plant -- ragweed.

Ragweed, Ambrosia psilostachya, a rather ironic latin name, can be found nearly everywhere. It infests your gardens, as well as nearly every sunny spot the seed lands. Most common along gravel roadsides, it is blooming now with an unremarkable green blossom stalk.

Wally Peck

This plant can produce up to a billion pollen grains in a season. The pollen grains are so tiny that they can travel on the wind for great distances so local eradication has little effect on your hay fever. Fresh gravel is heavily contaminated so roadway improvement actually contributes to the problem.

This is one tough plant! It is resistant to most herbicides except in high concentrations so chemical control is difficult. Mowing the plant forces it to bloom lower on the stalk and it does just that until the first killing frost.

Other native and garden plants are also implicated in allergic rhinitis as well. Goldenrod has been given a bad rap because it blooms at the same time as ragweed but the pollen it produces is very large and does not travel on the wind as well. Look instead to pigweed and nettle that is blooming now. Most allergy sufferers are allergic to these two.

Another common yard and garden weed, plantain, is also sending up bloom stalks now. They seem to send up another as soon as the mower goes over them. Again they are unremarkable as the flower is green but also produce a very fine pollen that carries on the wind.

Many with hay fever are allergic to tree pollen. The most common causes of spring hay fever are birch, willow and alder. Blooming in late summer are hornbeam (ironwood) and basswood. Spring blooming trees also include pines, cedars and spruce. There are others that cause allergy sufferers grief but these are the most common.

The other main culprit of hay fever is the grasses. Ryegrass and timothy are the main offenders but many others are allergens. They happen to be blooming now where fescues, crabgrass, brome grass, and quack are largely done.

Last, it should be mentioned that some of the perennial flowers in the garden are also high on the list to avoid for allergy sufferers. Since each person is allergic to a different mix of plants, you have to experiment until you find those that cause symptoms or submit to a “patch test.”

Serious gardeners can be found working in their gardens with a mask on at this time of year.

More horticultural information can be found on the University of Minnesota Extension website:

Master Gardeners are also responding to your horticulture questions at (218) 444-7916; leave your name, number and question and you will receive a return call.