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
Pruning suckers from roses and tomatoes, pruning old flowers from early perennials, and keeping the strawberry bed clean are some of the gardening tips for this month.
On grafted roses, any growth that originates below the graft union -- called suckers -- will not be what you bought the rose for. The foliage may look different and the flowers will be inferior, often a different color, to flowers on shoots growing above the graft. Clip off any sucker growth because it saps energy from the plant. These shoots are usually quite vigorous.
Many early bloomers, such as nepeta, veronica, delphiniums, and some perennial salvias such as 'May Night' will rebloom if you cut off the faded flowers. For bushy plants like nepeta and veronica and salvia, shearing with hedge trimmers is the easiest method.           

The best time to prune rhododendrons to improve flowering next year is right after they finish blooming.  The best tool to use is your hand. The dried flower clusters will snap off when you bend them, just be careful not to break off the tiny buds just below the old flowers which are the future blooms for next year.
Bright red lily leaf beetles are easy to spot on lily leaves and, if you only have a few, you can pinch them between your fingers or knock them into a can of soapy water. The larvae usually feed on the undersides of the leaves, and they have a slug-like body covered with their black excrement (ugh). You might want to wear gloves when squishing them. Neem spray is also effective against the larvae, and repeated sprays can kill the adults.
If you have a strawberry bed, harvest frequently and remove any berries that show signs of gray mold or rot diseases. These berries not only are inedible, they quickly spread the diseases to other ripening fruits. Pick and remove the rotten berries and mulch under plants with straw to reduce contact with the ground where the disease spores reside.
Blossom end rot shows up as dark, sunken spots on the blossom end of tomatoes, peppers, and squash. It's caused by a calcium imbalance in the plant -- the soil may have adequate calcium, but the plant isn't able to take up enough to supply the rapidly developing fruit. To minimize the problem, keep soil evenly moist, apply a layer of mulch to conserve moisture, don't over fertilize (avoid high-nitrogen fertilizer), and avoid damaging plant roots while cultivating.
"Indeterminate" or vining tomato plants produce many suckers -- new shoots that start where a branch connects with the main trunk. Removing suckers will decrease the number of fruits produced, but the remaining tomatoes will be larger and will ripen sooner.
Aspirin water has been found to promote healthy growth and enable plants to stand up to insects and diseases. Dissolve 3 aspirins in 4 gallons of water and spray plants. One time is all that's needed.
Iron phosphate granules, sprinkled around plants, are an effective, nontoxic pesticide for slugs and snails. (Brand names include Escar-Go and Sluggo.) Coffee grounds and liquid coffee are also effective -- the higher the caffeine, the better.

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