September FAQs


Q– What annuals can I plant this late?
A– Late annuals will last quite a while as accents in the garden or in containers. Cold-tolerant annuals include flowering cabbage & kale, petunias, asters, millet, mums and others. Protect these annuals from hard frost. Mums will tolerate only a very light frost. Continue to fertilize as long as plants are actively growing. The colors of flowering cabbage & kale deepen as the weather cools and persist until snow covers the plants. Asters provide nice fall color, also; however, these are actually perennials that will grow taller in the garden in subsequent years, so place them accordingly and provide winter mulch. 

Q– When can I stop fertilizing my annuals?
A– Apply fertilizer in mid-August to assure best performance through the remaining season. Then continue to apply as often as once a week until frost. However, the payoff lessens as cold weather approaches. Also, avoid getting fertilizer on nearby perennials this late in the season.


Q– When will your spring-flowering bulbs arrive in Retail?
A– We usually have bulbs available for sale starting the first week of September. They can be planted right until the ground freezes.

Q– Can I plant my spring-flowering bulbs now?
A– Yes, but it’s better to wait till October, by some opinions. Use Bulb-tone, not bone meal, which can attract animals. The most important time to fertilize bulbs is in spring, every year.

Q– How can I get tulips that will come back year after year, instead of getting just one year of good flowering from them?
A– Variety selection and soil quality are most important. For the best bet, choose Darwin Hybrids or Fosteriana or species (wild) tulips; most of these act as perennials. Experiment with other varieties, as some others may perform for you. Fertilize with Bulb-tone, and especially fertilize again during their active growth period in spring. Site them in a well-drained location in good soil in full or part sun. Plant larger varieties 8-10” deep, which is deeper than most written instructions usually indicate.

Dried Flowers:

Q– How can I preserve my flowers before they are killed by frost?
A– Harvest flowers that are suitable for drying before frost. Hang in small bunches in a dry, dark, airy location until dry. Harvest PG Hydrangeas around September 20th. 

Foliage & Flowering Indoor Plants:

Q– Should I do anything special when I bring my houseplants inside for the winter?
A– Check them for pests. Keep them isolated from other houseplants for a couple of weeks until you are sure they are safe, and inspect them again before mingling with others. Reduce fertilizer applications.

Q– How can I get my poinsettia (that I kept from last year) to turn color?
A– See “How to Care for the Poinsettia” information sheet. It involves artificially controlling the length of the daylight period.

Q– How can I get my Christmas or Thanksgiving cactus to flower?
A– Flower buds set as the day length declines. Growing them indoors under artificial light will interfere with this process, so grow indoors in an area that only gets natural light. Or leave outdoors until the nights are getting cool; bring inside before frost, and the buds should have set.


Q– What should I do for my lawn?
A– Continue to water if possible during dry periods. Apply lime if needed, but get a soil test first. Dethatch and aerate old lawns. Fertilize in the fall with a fall formula (low in nitrogen). This is also a good time to start new lawns; mulch the new seeding and keep evenly watered until the ground freezes.


Q– Should I fertilize?
A– No. Fertilizing at this time may encourage development of new shoots which will not have sufficient time to harden before cold, dry, winter weather. 

Q- How late can I plant container-grown or divided perennial plants?
A– Until approximately six weeks before the ground freezes. Plants will continue to put on root growth until the soil temperature consistently stays below 40 degrees. It is not recommended to plant evergreen trees and shrubs in the fall.

Q– Should I cut back my perennials in the fall?
A– Yes. Cutting back lessens the chance of disease and insects over-wintering on the dead foliage and causing problems next year. Also, fall cleaning reduces the amount of chores to be done in spring. When cutting back, leave about 1-2” of stem above ground. Do not cut back perennials that continue to provide late fall and winter interest, such as Sedums, Astilbe and Ornamental Grasses, until they lose their attractive forms. Also try to leave flowers that have seeds, such as Echinacea, for the birds. 

Trees & Shrubs:

Fertilizing: See Perennials.
Planting: See Perennials. However, use caution when planting broadleaf evergreens in the fall. Make sure they get regular water after transplanting, do not use fertilizer, and apply Wilt-Proof at appropriate times (later).

Q- Should I prune trees & shrubs in the fall?
A– As a rule, no, except for removing dead or diseased tissue.


Q– Should I fertilize?
A– Continue to fertilize as long as the plant is actively growing. For instance, kale and leeks continue to grow through fall, but onions have gone dormant by now. Use a high-nitrogen formula for leafy plants and high phosphorus for flowering/fruiting plants.

Q– Why are the leaves of my cole crops and root crops wilting?
A– Click here for information on Cabbage Maggots.

Q– How can I extend the Vegetable season?
A– Cold-tolerant varieties of vegetables and herbs can be grown under row covers, or even longer in a cold frame, until quite late in the season. Greens like lettuce, kale, spinach, turnip greens and arugula are suitable for fall crops.

Q– Can I plant garlic now?
A– Fall is the perfect time. Click here for how to plant garlic UMAINE cooperative extension video.


Q– How late must I continue watering?
A– The gardens still need sufficient watering. This is especially true for trees & shrubs newly planted. We recommend watering weekly with the equivalent of 1 inch of water unless you have relief from rainfall. Continue until the ground freezes. 


Timely Tips:

  • Plant late annuals for fall color.
  • Purchase spring-flowering bulbs, and start planting.
  • Plant garlic to harvest late next summer.
  • Harvest flowers for drying.
  • If houseplants spent the summer outside, check them for pests before bringing indoors.
  • Continue to water so that lawns and gardens receive at least one inch of total water per week.
  • Seed new lawn spaces.
  • Stop fertilizing perennials.
  • Continue planting trees, shrubs and perennials.
  • Start quick-growing, cold tolerant vegetable seeds.
  • Add compost to garden areas that have been harvested.
  • Dispose of diseased plant material in the trash (do not add to compost).
  • Saves seeds to plant next spring.
  • Make notes now for planning next year. 
  • Start a compost pile if you don’t have one.
  • Remove weeds before they release their seeds all over your garden.