September Tips and Tasks

— Written By

Cooler temperatures make gardening and landscape maintenance more enjoyable in the fall. There are lots of important tasks to do this time of year that will make your garden neat and tidy over the winter and get your garden off to a healthier start next season

 In the Vegetable Garden

  • There is still time to plant. In September, you can plant onions, radishes and second plantings of short season hardy crops like leaf lettuce and spinach.
  • Cabbage, kale, collards, Swiss chard and leaf lettuce can be set out through mid-October. Seeds of radish, spinach, turnip and salad greens can also be sown. Plant garlic cloves and onion sets until November. Choose short-day varieties of onions like Grano or Texas supersweet.
  • Cool season herbs like dill, parsley and cilantro can be direct sown or set out as transplants and will stay green into winter.
  • Extend the growing season of tender summer crops like tomatoes and peppers by covering them through the first couple of frosts. We often have several weeks of nice growing weather after the first fall frost.
  • Clean up. Remove old plants, as well as any foliage that has fallen on the soil and compost them. Do a final weeding, and mulch the bed with compost, straw, grass clippings, or chopped leaves. These mulches can be turned into the soil next spring to help fertilize next year’s crops.
  • Sample the soil to determine fertilizer needs for next growing season. In our area, gardeners should test the soil every 2-3 years.

 In the Perennial Bed

  • Fall is the best time of year to plant and transplant most trees, shrubs and perennials. It is also a great time to divide and replant perennials. Remember to keep new plantings well watered during their first several weeks as they get established.
  • Collect leaves and debris for composting but don’t compost insect or disease-laden plant material or weeds that have gone to seed.
  • As perennial beds go dormant, cut dry dead foliage back to ground level. Seed heads may be left for winter interest or to feed the birds (sedum, echinaceae, blackeyed susan).
  • Most ornamental grasses hold up to the winter weather so leave them for interest.
  • Prune shrubs to remove dead, diseased or broken limbs: however, save significant pruning for late winter or early spring. Spring blooming shrubs shouldn’t be pruned until after they flower, or you will lose next spring’s blooms.
  • Once all of the leaves have fallen, give your landscape plantings a layer of mulch over top. Three to four inches of mulch is good but excessive mulch can also cause problems so check the thickness of your mulch. Old mulch can be freshened up by raking. Don’t let mulch lie against the trunks of trees and shrubs or it will encourage pest and disease problems.

 In the Lawn

  • Warm season grasses do not grow during late fall and don’t require any nitrogen before spring. Fertilizing with nitrogen at this time will encourage weed growth and disease problems like large patch and winterkill. Instead, opt for a September application of a potassium fertilizer on sandy soils. Potassium can improve winter hardiness while improving disease and drought tolerance.
  • Raise the height of your lawn mower by ½ inch in mid-September to encourage your lawn to store energy for winter and protect your grass from winterkill.
  • Resist the urge to overseed your permanent lawn with ryegrass. While this provides winter color, competition with ryegrass in the spring can stress your lawn – particularly centipede and St. Augustine.
  • If you had large patch diagnosed this spring, apply protective fungicides the beginning of September and again in October for control. Also, make sure that you are not irrigating through the fall.