5 late-summer gardening tips for Minnesota


At this time of year, parking lot greenhouses have long since packed their bags. Sure, Cub still has a few outdoor plants welcoming you as you walk in, but there’s always the feeling that we (my fellow procrastinators) have missed the golden hour for gardening. A quick chat with Julie Weisenhorn, a extension teacher in horticulture with the University of Minnesota says otherwise, however. Here are five things you can do to start some factories, help certain factories, and even plan for next year.

It’s not too late to plant.

First, says Weisenhorn, you can replace early-flowering annuals with fall-flowering mums in your garden containers. It’s an easy pop of color, and they come in a rainbow of colors: red, gold, orange, pink, white, and even purple. While some varieties can be hardy enough to overwinter with proper care, most of the time they are treated like annuals. Fun fact: the pillow mom was actually the basis of the University of Minnesota’s first plant patent in 1977.

Weisenhorn’s own garden features other late-blooming flowers like joe pye weed (not a real weed, I promise) and anise hyssop. Although both have small blooms, the actual blooms are quite different: the tender pink blossoms of joe pye weed grow in sprays that range from tiny buds to delicate anemones, while hyssop anise – or like Weisenhorn calls it, “picnic on a stick for the bees” – has spiked columns that burst into light purple flowers, scent of licorice to match the scent of its leaves.

If you’re lucky, you might even see the state bug, the critically endangered rust-spotted bumblebee, wandering around, just like Weisenhorn did this year.

Water has no calendar.

Even if the sun does not cook your plants, keep them well watered until the ground is frozen, says Weisenhorn. This especially applies to trees and shrubs, which are also good to plant during those late summer weeks!)

When watering trees and shrubs, be sure to water deeply. The soil should be moist six to nine inches deep. Along with trees, Weisenhorn says most of the roots that nourish the plant are found in the top 18 to 20 inches of the soil, adding, “Nurturing roots aren’t that deep in a lot of trees, but go way beyond from the drop line up the canopy, into the yard or field. “

Bring the outside back.

If you have indoor plants you put them outside for the summer, you’ll want to bring them back inside before the first frosts. This can be earlier or later depending on the year, but regardless of the time, be sure to check them beforehand for bugs and weeds. You can also consider repotting them as the soil becomes crisp, depleted, and may contain insects.

Be warned that bringing your plants can cause them to take a bit of shock. The Weisenhorn’s hibiscus, for example, tends to shed its leaves when it brings them back indoors, as it tries to determine how much it needs in its new environment. Because of this adjustment period, Weisenhorn says now is not the time to take houseplants out for the last minute sun.

“There is a period of acclimatization for houseplants and for any plant that changes its environment,” she says. “Indoors to outdoors changes light, humidity, temperatures and exposure to wind, so it takes a little time, a few weeks for a plant to really acclimatize to its environment.”

Don’t worry about the dead head.

One-on-one or not one-on-one — Weisenhorn says it’s not a game or a breakup. The most important time for the dead head is when the plant is still growing so that it can direct its energy towards growing more roots, foliage and flowers rather than producing seeds. At this point in the summer, the practice won’t make much of a difference for most flowering schedules, but it could prevent fallen seeds from appearing as more of the same plant next year. On the flip side, if you don’t play dead, the pods can add winter interest to the inevitable snowy landscapes or provide food for wintering songbirds.

Spring bulbs are starting now.

Something to start thinking about is fall bulbs. Some strains may already be sold out, Weisenhorn warns, but there should be plenty of other strains to choose from. Just make sure you get bulbs that are hardy for our climate zone. Think of early blossoms and garden favorites like crocuses, tulips, daffodils, hyacinths, striped scilles and … Garlic.

“As with other bulbs, you can order garlic from a garlic grower – there are a number of them in Minnesota,” Weisenhorn explains. “You want to use garlic from a grower and not a store, because the growers have the right type of garlic for the Minnesota climate.”

Even if you continue to procrastinate, don’t worry: you don’t want to plant your bulbs in hot weather, and Weisenhorn can testify that, in a pinch, planting bulbs even when it’s snowing has worked.

“The great thing about fall is that even though people are tired at the end of the season – ‘oh, I’m sick of doing gardening stuff’, plant those bulbs and take that time has a great reward when you see the the colors and the plants appear, ”says Weisenhorn.


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