Unfortunately, our growing season is winding down and now is the time to start readying your lawn, garden and landscape for the coming winter season, as well as get a head start on spring. Do you want to relocate a tree or shrub? Do your perennials need to be divided? Do you want to add some spring blooming bulbs? September is the time to get busy. Here are some tips to get you started…

Trees and Shrubs

For most deciduous shrubs and trees– late August to mid-September is a good time for transplanting! Fall transplants can benefit from the cooler, moister weather ahead. Thanks to autumn rains, the plant’s roots will get a chance to grow and develop and allow them to stock up on needed nutrients before the ground freezes.

The best time to transplant raspberries and blueberry bushes is when they’re dormant. Any time between fall and spring when they’re not fruiting or growing new leaves. October through December are ideal as long as the ground is not frozen.

You can transplant evergreen trees through early September. This is actually the preferred time for transplanting evergreens since it gives those trees the entire winter season to reestablish root systems. This will usually mean the tree will be less stressed and can recover faster in spring. Once you reach late September, your evergreens may not have adequate time to reestablish adequate root systems.
Be sure to water every 3 to 4 days for the first few weeks after transplanting, and at least once a week until the ground is frozen.

Perennials/Bulbs

How do you know if your perennials should be dividing? Did they produce smaller blooms than past seasons, develop a ‘bald spot’ at the center or require staking to prevent their stems from falling over? Then they need to be divided. You may also decide to divide perennials to redistribute to other garden locations. Plan your spring garden now and add your perennial divisions where desired.

As a general rule, spring and summer blooming perennials should be divided into late summer/early fall and fall blooming perennials in the spring. After dividing clumps transplant immediately to keep them from drying out.

Peonies. Dividing peonies in September allows them to become established before winter. In late fall, mulch newly planted peonies with several inches of straw or pine needles, removing the protection in the spring when new growth resumes.

Daylilies can be divided in September. Dig up the clump, shake to remove soil and carefully pull the clump apart. You may need to cut them apart with a sharp knife. Each division should have a good root system and at least three leaves. Replant the divided clumps immediately, so the crowns are one inch below the soil surface.

Bearded Iris should be divided typically (every 3-5 years) when clumps become too large or when flowering decreases. Carefully dig up clumps, cut leaves back to one-third of their height, wash off and cut rhizomes so each division has a fan of leaves and a healthy rhizome with several good-sized roots. Discard old rhizomes from the center of the clump. Dig a shallow hole just slightly deeper than the root portion of the iris, and then create a slight mound of soil in the center of the hole. Position the rhizome section over the mound so the roots spread out facing downward and the top of the rhizome is just above the soil line. A common mistake is to plant iris too deep. Pack new soil around the iris, and then water thoroughly.

Spring Blooming Bulbs. Late September or October is the time to plant spring-blooming bulbs such as daffodils, crocuses, snowdrops, tulips, hyacinths, irises and alliums.

To stimulate root growth, scratch a small handful of granular fertilizer into the soil at the bottom of the hole, and flatten the area with your hand so bulbs have a stable surface on which to rest. Place bulbs in the prepared hole about an inch apart, with tip up and root end down. Cover with soil, and water once to settle them.

For a dramatic show of spring-flowering bulbs, plant smaller perennial species near larger bulbs. That way, you’ll get twice the vibrancy in the same space.

Vegetable Crops

It’s important to clear away diseased plants and any dead or rotting plant material. Pest insects, like squash bugs, and diseases will overwinter, bridging the gap between this year’s crops and the next.

Chop beans and peas off at ground level, leaving their nitrogen-fixing roots in the soil to feed next year’s crops.

Fall is a great time to work to improve the quality of your soil. If you have harvested garden plants such as beans, sweet corn, or carrots and are left with an open space, consider planting a cover crop. Cover crops help to prevent erosion, add/retain nutrients by providing organic matter, and dispense many additional benefits to your soil. Apply compost in a one-fourth-inch layer and spread thinly to improve the soil structure.

Pull small weeds and cut off large ones before they go to seed and remove them from the garden. Removing weeds before their seeds mature will decrease the number of weeds that will grow in your garden next year! Winter annual weeds like henbit, common chickweed, and shepherd’s purse will germinate in the fall and resume growth in spring. Managing them now prevents weed problems in the spring!

Lawns

Set your mower blades fairly high for the season’s final cut leaving the grass to grow a little longer over the winter. This higher cut will protect the soil and make your turf healthier. Soil-enriching caterpillars and other bugs bury right down into the thatch; a close-cropped lawn doesn’t do them any favors. Take the grass catcher off your mower and mow over the leaves on your lawn. You want to reduce your leaf litter to dime-size pieces. It might take more than one pass with the mower to get the shreds to the desired size, depending on the leaf type and volume. You will know you’re done mowing leaves when about half an inch of grass can be seen through the mulched leaf layer. Once the leaf bits settle in, microbes and worms get to work recycling them. Decomposing leaves add nutrients to the soil, which in turn can nourish your grass, add beneficials and reduce weeds in the spring.

Late-August through mid-September is a good time to renovate lawns, repair bare spots, and plant new lawns. If you are renovating or reseeding your lawn, it’s important to pick the right kind of grass for your situation. Each of the four most popular cool-season lawn grasses have strengths and weaknesses and it is important to consider maintenance issues and sun/shade components. So be sure to do your research.

Hopefully, you will find this information helpful.

Happy September from The Webster Arboretum!