September marks the start of getting the garden – and the gardener – ready for a long winters rest. To this end, consider how best to overwinter and to make room for your favorite non-hardy plants indoors, as well as considerations for your outdoor hardy plants and any new plantings. Fortunately, we still have several months remaining for plants to grow, so there is no rush! Continue to take good notes and pictures on how you weaved together your perennials and annuals this year, since after the first frost these pictures will be all that remains of this year’s favorite combinations!
Things to do:
- Continue to keep your lawn mower blades set high for cutting your lawn. Rain has been ample, although rather sporadic. The temperature look to be average or cooler for the start of the month, which will minimize the stress on the turf.
- September is a great time for the reseeding of bare spots, or for the installation of sod. The upcoming cooler temperatures, heavy dews and typically consistent autumn rainfalls combined with warm soil temperatures promotes good root growth and turf establishment.
- September is a good time to fertilize your lawn. If you wish to fertilize once a year, September is an ideal time as it aids in developing a good root system throughout the winter for next summer’s heat.
- September is a good time to aerate those portions of the lawn that receive excessive foot traffic or have otherwise developed compacted soils.
- If you have yet to start, take cuttings of your favorite annuals that you wish to overwinter. It will be ready to be potted-up in 4-6 weeks. It is far easier to over-winter a small plant that should be free of most insect and disease than lifting a large plant from the ground or outdoor container and bringing it inside.
- Harvest and clean the seed from those annuals and vegetables that come true from seed. Allow them to dry and store them in small paper pouches that are properly labeled and place them in the refrigerator (not the freezer) until next spring.
- Remove those annuals that look excessively tired or leggy and keep removing annual weeds such as crabgrass and stilt grass. Annual weed seed will continue to germinate and appear as long as the temperatures are warm. Remember, on average a seed lasts for seven years and one plant going to seed equates to seven years of additional work!
- Send in your bulb orders! October is a great month for planting bulbs. For Colchicum (Pictured at right), get in your orders in early September or look for them in your favorite garden center. They bloom in late September into early October with typically pink or white flowers and they are deer resistant!
- As a reminder, don’t order just 6-12 bulbs if you are looking to make an impact. For minor bulbs (bulbs that measure close to ½” in diameter), you typically need 50-100 bulbs to begin to make an impact and obviously, the more the better. These bulbs include Snowdrops (Galanthus), Squills (Scilla) Grape Hyacinths (Muscari) and pictured below, Glory of the Snow (Chionodoxa) species. For major bulbs, such as Daffodil (Narcissus), Tulip (Tulipa) and Flowering Onions (Allium) species, 25 to 50 bulbs will make an impact on the Garden.
- For both major and minor bulbs, I like to cluster several bulbs in a hole to create a more mature appearance. For minor bulbs, clusters of 3-8 work well while for major bulbs, clusters of 3-4 give a more mature appearance from the start. These are all things to keep in mind as you put together your bulb order!
- Inspect and evaluate your ornamental small trees, shade trees and shrubs. Even though it has been a relatively moist summer, those plants that are stressed from age or disease will let you know through early leaf wilt or drop. Oaks that have Bacterial Leaf Scorch will have leaves that suddenly turn brown in mid to late August. There are treatments for this disease, but once most of the foliage has turned brown the tree will ultimately need to be removed. It typically attacks older, less vigorous trees and young oaks should still be planted, since the trees feed over 500 native insects!
- September is an ideal time to add woody and herbaceous plants to the garden. The soil is warm and although it is often a relatively dry month, the cooler days and moister weather ahead will allow the plants to establish an adequate root system before next summer’s heat and potential drought. Woody plants that are not fall transplant hazards can be dug and transplanted, and those that are fall hazards can be planted if they were dug this past spring or grown in containers. If rainfall is scarce, water new plantings every 3-4 days through the end of October.
- For the vegetable garden, continue to remove plants that are no longer producing. The wet weather of July and early August raised havoc with tomatoes as the fruit is subject to splitting and cucumbers faded from Powdery Mildew. As mentioned last month, Dr. Bob Mellert mentioned that the days to maturity on seed packets applies for springtime seeding. Come autumn, the number should be multiplied by 1.5 to account for the slower growth time due to the shortening days as compared to the lengthening days of spring. Plant leafy crops that appreciate the cooler nighttime temperatures, such as Arugula, Spinach, Bok Choi, Kale and Lettuce. The full list is below:
- If you are planting in containers, consider the leafy crops like Spinach and Bok Choi. They will provide well into the beginning of winter.
- Consider the installation of low tunnels, as seen at right, which are metal hoops covered with a fabric called Agribon. The fabric keeps heavy frosts off a row of cool season vegetables. It enables the gardener to harvest well into December, and for certain crops, into spring! September is a good month to pick-up the materials needed to construct the low tunnels.
- September is an opportune time to plant garlic too! ‘Music’ is an old fashioned favorite and a good performer, but try some of the many other selections that are on the market too! Plant in a location that will be in full sun through next August, which is the harvest period.
- If you live with large deer populations, put wire cages around recently planted trees to avoid the bark being rubbed and damaged by bucks. One of their favorite targets are Magnolias, so make certain that they are properly protected. Damage to bark is far more harmful than the nibbling of a few leaves and I have lost many a tree before we start installing cages.
Beets (45-64 day)
Carrots (65-80 day)
Fennel, Bulbing (72)
Scallions (60 days)
Kohlrabi (45-60 days)
Radishes (21-48 days)
Lettuce (45-55 days)
Mache (like lettuce) (40+)
Mesclun Mixes (30-40 days)
Bok Choy (45 days)
Salad Greens (28-42 days)
Spinach (45 days)
Chard (28-42 days)
Program Leader, Home and Public Horticulture (NJAES)