Nancy Helms, Extension Master Gardener in Anoka County, September 10, 2015
Days are getting shorter and leaves are starting to change color. As tedious as weeding has become, now is not the time to quit. To have that a healthy, beautiful garden next year, work needs to be done. That can only mean one thing—time to get your autumn gardening in gear.
Inventory. How often have you forgotten planting a perennial the year before, only to start digging in the spring and find out too late? Label, map or diagram your perennials. This is also an opportunity to change, rearrange and plan new additions for next year. Pictures will help memory with color, height and spacing in the spring. Start a list of plants you want to add next season.
Think bulbs. This is a great time to plant bulbs that will bloom in the spring. Most bulbs require about 6 weeks to form roots before freezing. Daffodils, tulips, crocus, hyacinth, squill and alliums add lovely spring color. Garlic and shallots can be planted now for harvest next summer.
Clean. This is the time to clean up dead foliage. Pick the last of the green tomatoes. Harvest any remaining vegetables. Put diseased plant material in the trash. If some areas have hopelessly gone to weeds, cover them with black plastic and leave it in place over the winter and into the spring to kill sprouting seeds.
Save. If you have an annual that you absolutely loved this season you might overwinter it. Just as you have to harden off tender plants in the spring, gradually bring plants indoors to allow them to adjust to the indoor climate. You can also take cuttings and root on your windowsill. Lantana, geraniums and begonias are good cutting candidates. Now is the time to collect seeds. Once the seeds have finished developing, shake them into an envelope. Label and store in a dark, dry place for next year.
Mulch. Most likely, the organic mulch you put down in the spring has substantially decomposed. Spread new mulch now, a thicker winter layer, to protect plants and soil over the winter months. The idea is not so much to keep the soil warm as it is to keep the temperature even. Convert fallen leaves to mulch and use it throughout your garden.
Dig. After the foliage has died, dig up any tender bulbs you have planted such as dahlia, cannas and callas. Shake off excess soil and cut off stems. Dry out of direct sunlight for 1-3 days before storing in a cool, dark, dry place between 35 and 45ºF.
Divide. The best time to divide Iris is late summer to early fall, when the plant is semi-dormant. This will give the plant ample time to re-establish in order to ensure flowering next season.
Water. Water your perennials, shrubs and trees; they will thank you for it next spring.
Start. Find a comfy chair, a good light and gather your inventory (see above) and seed catalogs. Start planning for next year!