University of Vermont Extension 
Department of Plant and Soil Science

Fall News Article
line
   
DIVIDING IRIS AND OTHER SEPTEMBER GARDENING TIPS
 
Charlie Nardozzi, Senior Horticulturist
National Gardening Association, and
Dr. Leonard Perry, Extension Professor
University of Vermont
 
        
Lifting and dividing iris and daylilies, rooting cuttings of tender plants, and burying bean vines are some of the gardening tips for this month.
        
Root cuttings of coleus, geranium, and herbs to bring indoors over the winter. Cut a three-inch section of stem, remove the bottom half or two thirds of the leaves, and place in moist soilless mix, vermiculite, or sand. (Some gardeners dip the cut ends in rooting hormone; others find this unnecessary.) Place the entire container in a loosely tied plastic bag to maintain humidity.
        
When the daytime temperatures no longer rise above 65 degrees F, it's time to pick the green tomatoes. Wrap them individually in newspaper and let them ripen indoors.
        
Lift bearded iris clumps with a shovel and break them apart. Save the plumpest, firmest rhizomes, and discard the old, leafless ones. Trim the leaves to about six inches long. Let the rhizomes air dry overnight before planting. Daylily clumps are so dense you'll need to slice through them with a shovel or spade. Separate them into smaller clumps, leaving at least three plants per clump. Trim leaves to about six inches long and replant.
        
Legumes, such as beans and peas, have the ability to take nitrogen from the air and use it for their own benefit. Rather than pulling up the spent plants and adding them to the compost pile, why not keep that nitrogen where it's needed by chopping up the vines and tilling or digging them into the soil.
        
The sales are on. There's still plenty of time to plant trees and shrubs, and the prices are right. Root growth will continue into late fall or early winter, and plants won't have the heat of spring or summer to dry them out. Be sure to water well at planting time and every week until they go dormant. If you don't have a spot ready for your new additions, submerge roots in the vegetable garden until next spring-- pot and all.  Just make sure when choosing plants to select healthy specimens, ones without broken stems, diseased leaves, or misshapen growth.
        
If you have any existing small trees or shrubs you'd like to relocate next spring, prepare them now with a process calling “root pruning”. With a sharp spade, slice down into the soil around the rootball. This will cut through the roots and encourage the growth of new roots, which will ease transplant shock later on.  Only select plants about your height, as large plants will be difficult to dig sufficient roots to move successfully.  Larger trees and shrubs may need the equipment and skill of a professional landscaper to move. 
        
When the first frost blackens the foliage of dahlias (or if a hard freeze is predicted), cut off the stems about six inches above the tubers. Carefully dig the clumps with a spade or fork, and rinse them off. Let them dry out of direct sun and wind for a day (not too long or they'll begin to shrivel). Store the tuber clumps whole, or carefully separate the tubers from the stem, making sure to include any "eyes" (small, raised nubs near where the tubers attach to the main stem) with each tuber. These are the future sprouts. Store tubers in ventilated plastic bags filled with peat moss,
vermiculite, or sawdust. Place bags in a box and keep them in a dark, 35- to 50-degree F location.
        
If you haven't yet done so, cover your late crops of lettuce and spinach with polyester row covers to keep them warmer as the night temperatures dip close to freezing. The covers also will keep the leaves from getting damaged by heavy rains.
        
Hard as it is to do, refrain from cutting any more roses and let the fruits (rose hips) form. This will signal to the plant that it's time to harden off for winter. Don't spread winter mulch around roses until after the ground freezes.
        
You can keep geraniums in pots growing and blooming indoors by cutting them back by about a third and then starting to fertilize them a couple of weeks later. Keep plants in a sunny window. Or to keep them dormant for the winter, move the potted plants into a dark, cool (40 to 50 degrees) location. Don't water them and don't cut them back until they show new growth in spring.  Many other annual flowers can be potted before frost, and kept blooming indoors well into fall.
  

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