As the gardening season winds down, it’s time to prepare your garden for the transition to fall. This gardening checklist will help you tackle essential late-season tasks to ensure your plants thrive through winter and emerge healthy next spring.
Perennials
As summer starts to wind down, our perennial plants tend to look tired and begin the process of redirecting energy from the foliage back to the root systems. Late summer is a great time to divide overgrown herbaceous perennials that are no longer blooming.
When dividing perennials, dig around the entire base of the plant, saving as many viable roots as you can. Then use a sharp shovel or spade to divide into 2 or more clumps. Return the clumps to the soil at the same depth that you found the original and water them well. Allow 4-6 weeks before the ground freezes to give the roots time to establish themselves. Depending on where you live, this typically occurs around the end of November or the beginning of December. It is best to divide perennials with large “fleshy” or tuberous roots, like peonies and iris, in the fall. Wait to divide any fall-blooming plants, like perennial mums or upright sedum, until next spring.
Bulbs
Fall is the perfect time to plant spring-blooming bulbs that will reward you with beautiful flowers after a long winter. Tulips, daffodils, hyacinths, crocuses, and alliums should all be planted 6-8 weeks before the ground freezes hard, typically from late September through November. Plant bulbs at a depth that’s about three times their height – so a 2-inch bulb should be planted 6 inches deep. Make sure to plant them pointed end up! Choose a well-draining location, as bulbs will rot in soggy soil. Don’t forget about garlic! Plant garlic cloves in late fall, about 4-6 weeks before the ground freezes. Plant individual cloves 2 inches deep and 4-6 inches apart with the pointed end facing up. Garlic needs that cold winter period to develop properly, so fall planting is essential for a good harvest next summer.
Annuals
Your annual flowers might also start to look like they are running out of steam. This is a great time to switch them out. Annual mums, ornamental kale, and grasses make a perfect substitute for summer-blooming annuals because they will tolerate the colder nights ahead. This is a great way to renew your annual containers and prolong the season!
Vegetables and Herbs
Vegetable and herb gardens should be harvested regularly this time of year. You may find yourself thinking, “Why in the world did I plant so many vegetables?!” but what a great problem to have! Continuing to harvest will keep your plants pest-free and healthy. Consider freezing and canning what you can’t eat or give away. Your future self will thank you! Starting a gardening journal can be very helpful as you evaluate what worked well and what didn’t. Make a note of what you may have gotten carried away with this year, so next spring you can plant your vegetable garden more efficiently.
Houseplants
If you have any houseplants outside, late summer is a good time for a systemic insecticide to take care of any unwelcome pests before you bring them in for the winter. Some houseplants, like orchids, are very sensitive to cool weather. When the overnight temperatures start to drop below 50° F, be prepared to bring them inside. It is important to clean all your outdoor houseplants thoroughly in addition to doing a systemic treatment, especially if you know you have problems with pests. This will help to protect your other houseplants from infestations.
Trees and Shrubs
Whether you lost a tree or shrub to wildlife, storm damage, or just plain bad luck, you may be planting a replacement this fall. Be aware of the previous root systems of whatever was lost. When replacing a large tree or shrub, you’ll need to allow at least 3 to 6 feet from the original location, and sometimes up to 10 feet depending on the size. It is very important to water a newly planted tree or shrub regularly, especially in the fall, because the roots must get established before winter. For the first two weeks, water daily. Then scale back to 2 to 3 times a week for 12 more weeks. After 12 weeks, water weekly. Unless more than 1 inch of rain falls in one day, do not rely on the rain to water your newly planted tree or shrub! Proper mulching is also important, as it will help to maintain moisture and control weeds, and consistent watering is critical for root establishment before winter.
Lawn Care
Towards the end of the season, it is not unusual for drought and heat to cause lawns to become dry and stressed. Do not mow a heat-stressed lawn, as it likely is not growing much anyway. If you must mow, wait until after a good rainfall and do it during the evening when the temperatures are cooler. Lawns should be left longer during periods of drought to avoid further stressing the turf.
Fall is also an excellent time for overseeding thin or bare spots in your lawn. The cooler temperatures and typically more consistent moisture make it ideal for grass seed germination. Before overseeding, rake the area lightly to remove debris and create good seed-to-soil contact. Choose a grass seed that matches your existing lawn type. Keep the seeded areas consistently moist until the new grass is well established, which usually takes 2-3 weeks. Try to avoid heavy foot traffic on newly seeded areas until the grass has had a chance to fill in.
Seasonal Wrap-Up
Congratulations on completing your end-of-season gardening checklist! Your fall preparation efforts will pay dividends come spring, especially given Minnesota’s unpredictable spring weather patterns. Take advantage of these pleasant late summer days to tackle these important tasks—your future self will thank you for the preparation.
Now get outside and enjoy the beautiful late summer weather while it lasts!