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Late summer garden checklist

The State Fair is going on. Nights are actually getting cooler even after the heat waves we’ve experienced. Our gardens are producing, but we can tell the plants are changing. Still, there's lots of gardening yet to do!

Harvest your vegetables and fruits

Branch of a black chokeberry shrub with leaves and clusters of dark berries.
Tart and tannic when fresh, Aronia berries can be made into juice, jelly and jams, and are high in antioxidants. The plant provides white spring flowers that benefit bees and other pollinators.

Keep pulling in those peppers, tomatoes, kale, herbs, cukes, squash, choke cherries and chokeberries, strawberries, apples, pears and whatever else you have left.

Think about how to safely preserve your harvest. We have lots of information on Preserving and preparing food safely.

As you finish harvesting a crop like beets, plant a crop for late fall in its place that has a short days-to-maturity time like baby pak choi, peas, spinach or radish.

Get some guidance about Planting vegetables in mid-summer for fall harvest.

Keep on weeding

Weeds continue to grow into the fall and can compete with your flowers, trees and shrubs for valuable nutrients, light and water. They also play host to insects like leafhoppers that can carry pathogens like aster yellows and infect your favorite asters.

Fall is the best time for lawn care

Renovating, fertilizing and broadleaf control are covered in Extension turfgrass educator Jon Trappe’s September lawn care checklist. And check the Minnesota Lawn Care Calendar for other tasks you could be doing now.

Water trees and shrubs

Especially evergreens. We water faithfully during dry summers but may slack off a bit as the season comes to a close and we get busy with school starting, the State Fair, and end-of-summer fun.

Continue to water plants to help them successfully go into the fall and winter fully hydrated. This is especially important for evergreens as they hold onto their needles through the winter and dehydrated evergreens can experience winter burn resulting in brown needles. 

See Watering established trees and shrubs and Watering newly planted trees and shrubs.

Stop pruning and fertilizing trees and shrubs

Pruning prompts new growth where you make the cut. Fertilizing also will prompt the plant to put on new growth. This new growth will not harden off before cold weather hits and it will die.

Deadhead perennials

Removing spent blossoms from plants like yarrow and bee balm can result in a second flush of flowers. Though not as prolific as the initial bloom, it’s always great to have that extra bit of color that also feeds late-season pollinators.

Replace spent annuals with fall mums

Green, purple and white Nagoya kale plants
Ornamental kale like the variety Nagoya Mix can tolerate cooler weather and add great texture and color to late-season gardens and containers.

Containers may be going downhill by now. Swap out annuals that are finished blooming with the classic fall flower — mums.

Ornamental kale is also attractive in containers and in areas of the garden where your annuals have wrapped up the summer.

There’s still time to plant

Visit your local garden center for deals on hardy perennials, trees and shrubs and get them in the ground right away. Planting perennials can go on into early September. Trees and shrubs can be planted as well.

Be sure to water these new plants daily (depending on rain) and mulch them with shredded wood mulch. Mulch protects plant roots from damage, holds in soil moisture, and moderates the soil temperatures so your plants can move gradually into winter.

Author: Julie Weisenhorn, Extension horticulture educator

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