September is a wonderful gardening month. The last of the summer vegetables are ripe and ready for eating or preserving, apples are at their peak in many places, and it time to clean up and prepare for next spring. The days are bright and mornings can be crisp. In more moderate climates, summer stretches yet a bit longer but autumn is in the air.
Once plants have started to peter out, it’s time to pull spent annuals and vegetables. If you’ve had no significant plant problems like bugs or fungus, add them to the compost pile. If you have had problems, don’t compost. Burn if you can, otherwise trash them.
Cut out dead shoots on roses. Destroy leaves with evidence of mildew or blackspot to diminish the probability of a recurrence in the spring. And stop feeding your roses. They need to prepare to go dormant.
Plant Spring Bulbs, Peonies, & Iris
September and October are the best months for planting spring bulbs. Decide where your bulb beds will be, then build them up with fresh compost. Beds should be deeply dug and well drained.
- Early planting in September is important for anemones, snowdrops, and winter aconite.
- Make sure tulips and daffodils go in the ground six weeks before freezing weather sets in.
- Plant lilies as soon as you get them.
- Peonies and iris can be planted from August through September. Anticipate a great show in May and June next year.
Also, now is a good time to prepare bulbs for indoor forcing. Fill clean, dry pots with fresh soil. You can leave them outside in a protected area and cover them with straw or leaves. In a month or so, after root development has had a chance to occur, you can store them in a basement or garage and gradually expose them to light and heat. They should begin to show signs of life in December.
Begonias will live happily inside throughout the winter. Next spring, you can create many new plants.
Plan for Next Year’s Vegetables
Prepare for next year’s perennial vegetables now.
- Mulch rhubarb.
- Cut off old asparagus tops.
- Set up cold frames to prepare for early spring vegetables.
Annual veggies need attention now too. Where an early frost is typical, pull up tomato vines and hang indoors. The sap will be sufficient to ripen fruits. Half ripe tomatoes will ripen indoors on the counter. Green tomatoes can be turned into jam or chutney. Harvest onions before they resprout. Squash should be picked before frost. Root vegetables like beets and carrots, pulled before the first heavy frost, will do well stored in sand in the garage or basement.
Plant Trees, Shrubs & Early Spring Perennials
September is prime time for transplanting both large and small perennials. Shrubs like pussy willow, forsythia, and lilac as well as many evergreens do well being planted before winter weather arrives. Make sure evergreens are well watered so they don’t suffer from dry cold, which will kill them. Divide and transplant early blooming perennial flowers like poppies and bleeding hearts. Large clumps can be split now too. Find a friend or neighbor to trade with and add a few new varieties.
Prepare clean pots and fill with fresh soil, then transplant tender perennials like lemon verbena, geranium, and bay laurel so they can be overwintered in the house or on a sun porch. If weather isn’t freezing they can go outside on milder days.