University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article
Charlie Nardozzi, Senior Horticulturist
National Gardening Association, and
Dr. Leonard Perry, Extension Professor
University of Vermont
Taking cuttings of azaleas and favorite annual flowers, harvesting onions, and sowing cover crops are some of the gardening tips for this month.

To propagate your favorite azaleas, take six-inch long cuttings from new growth, strip off the lower leaves and remove any flower buds, dip the cuttings in rooting hormone, then stick the cuttings in moist seed-starting mix. Make sure the leaves don’t touch the mix. Cover the pot with a plastic bag to hold in humidity, and set the pot in a cool, shady, protected location outside. When cuttings have rooted (in about eight weeks) remove the plastic covering by rolling it back a little more each day, and transplant the cuttings into a protected location or in a cold frame to overwinter.  Be sure to mulch well.

Take cuttings of favorite geraniums, coleus, begonias, and any other annual flowers that you want to grow again next summer.  Also, you can bring these plants indoors for the winter if you have a sunny spot.  Several popular bedding plants are perennial in warm climates and can be brought indoors as houseplants if you don't wait until the weather gets too cool, which can set them back and make it hard for them to recover. Gradually move the plants into shadier locations so they are better adjusted to the reduced light levels when you move them indoors.
Begin harvesting onions when about half to three quarters of the leaves have died back. Gently dig or pull the onions and store them in a dry, shady place with good ventilation, such as an outdoor shed or barn, for 10 days to two weeks. After the onions have cured, separate the young, soft, and thick-necked bulbs and use them first because they won't store well.  Put the rest in slatted crates or mesh bags, and store them indoors in a basement with low humidity and temperatures between 33 and 45 degrees F.

It’s time to start some mesclun greens and leaf lettuce in bare spots in the garden for fall picking. Mix in some compost before seeding and give new seedlings a dose of liquid fish emulsion.
Build the nutrient levels and organic matter in garden beds by sowing cover crops like annual ryegrass or buckwheat into empty annual beds. They will grow until winter kills them and then can be incorporated into the soil in spring. Cut down buckwheat before it flowers so seeds don't become a problem.
Late summer is a good time to divide German and Siberian iris, rudbeckia, echinacea, daylilies, and tall phlox.  If plants are blooming well, with strong stems, and you still have space for them, they shouldn’t need division.  Don't make the divisions too small or you'll wait longer for blooms. Wait until after bloom to divide.  Trim the foliage by at least half before replanting.

Be sure to set bearded iris rhizomes (the thick roots) just barely below the soil surface to prevent rotting.  When dividing these iris, check the rhizomes for mushy areas with borers.  Discard affected roots, making sure to kill the borers.   

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