June garden checklist

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

Perplexed about your peonies? Lawn got you down? Tune into our WCCO Radio “Smart Gardens” show on Saturdays, 8-9 a.m., for answers to your lawn and garden questions. Dial in AM 830 on your radio or ask your smart speaker. Or listen to Smart Gardens podcasts when you have the time.

Mystery of the month

This plant with thin, yellowing leaves was moved outside two weeks before this photo was taken. What happened?  

Find the solution to our mystery at the end of this article.

Pests and diseases

Be on the lookout for garden pests in June.

• Place traps for apple maggots in your apple trees by the end of the month, because apple maggots become active in early July.
• Or, you can use extra-fine mesh or plastic bags to prevent apple maggots from burrowing into the fruit. Make sure you put the bags on by mid-June.

Trees and shrubs

• Mulch and water your newly planted trees and shrubs when there is no rain in the forecast. For the first 3 to 5 years after planting, these plants require regular watering to develop strong root systems.
• Mulching with 3 to 4 inches of shredded wood mulch helps suppress weeds, conserve water, and protect roots from excessive heat and potential mechanical damage. Create mulch rings as wide as the plant’s canopy, and avoid piling mulch around the base of the stems.
• See watering newly planted trees and shrubs for more information.

Flowers and other garden plants

• Check your pots and hanging baskets regularly, especially those in full sun and exposed to wind. Sometimes the pots will need to be watered more than once a day!
• The more you water, the more often the containers will need to be fertilized.
• Correctly fertilizing and watering container plants is critical for plant success.

Houseplants

Start moving some houseplants outside for the summer once nighttime temperatures are at least 60°F.

Don’t put them in full sun or a windy location right away. They should be slowly acclimated, or hardened off, to the great outdoors:

• First, place them in a shaded location that is protected from wind for a few days.
• Then move them to a slightly sunnier location for a few days.
• Finally, put them in their final location for the summer.

This will prevent the leaves from getting sunscald, which can permanently damage them.

Lawn

How we manage our lawn now affects its performance for the rest of the growing season. Two key management practices have a significant impact on your lawn’s ability to withstand stress: mowing height and watering practices.

Ensure your mowing height is at least 3 inches. A taller mown turf is more resistant to weeds like crabgrass from encroaching, is more drought-tolerant due to having deeper roots, and even means the lawn will need to be mowed lessoften.

Now is the time of year when you can train your grass roots to grow deeper, allowing for a more drought-tolerant lawn. You can achieve this by not watering regularly.

• Regularly watering according to a schedule (such as every other day) trains the roots to grow near the surface.
• By mimicking Mother Nature and watering deeply into the soil less frequently, you can ensure a deeper-rooted lawn.
• Deeper roots will have access to more water in the soil, resulting in turf that stays green longer and is less susceptible to drought.

Other tasks

Thin direct-seeded plants to their final spacing, and make sure to pinch back some plants for bushier growth. Plants that may require thinning include radishes, carrots, beets, and alyssum.

Peppers, basil, and zinnia are all plants that typically do well with an initial cutting back.

• For peppers and zinnias, pinch them when there are 3 to 4 sets of fully developed leaves.
• Remove the top of the stem, leaving 2 full sets of leaves.
• Use clean, sharp pruners and make your cuts at a slight angle so water does not pool at the top of the stem.
• Basil can be pinched back all summer long for a continuous harvest of leaves.

Growing peppers in the home garden has more detailed information on growing productive pepper plants in Minnesota.

Solution to the mystery of the month

The umbrella plant, which was growing indoors all winter, was moved outside into direct sunlight too quickly. The tender leaves are prone to sunscald (like a sunburn) and will not recover from the damage.

This photo shows healthy leaves that developed 100% outside, so they are not negatively impacted by the sunlight they receive, unlike the leaves that were already growing inside.

Houseplants should be slowly acclimated, or hardened off, to the great outdoors.