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Use heat as organic way to kill weeds

QUESTION: “I have looked all over the internet for information on the effects of Round Up (weed and grass killer), but can't find anything. We are trying to prepare a vegetable garden that's in the middle of the yard. It's not a raised bed; it's level with the grass. Over the winter, tons of crab grass and various weeds have crept in.

“So far, we have been totally organic, using just compost as fertilizer, pulling weeds by hand, but the situation is BAD, and we have three little kids and very little spare time. Someone told us to apply Round Up, cover with plastic, wait three days, and the chemicals would have broken down. Is this true? Will Round Up kill all our worms and other beneficial bugs? Any knowledge you can share would be appreciated.” – Jodi

ANSWER: Round Up is a contact herbicide that kill plants by going through the foliage and down into the root. You should not have to cover with plastic; simply spray what you want to kill. However, you will continue to have weed seeds in the soil and they will also germinate. To get rid of the weed seeds you will have to spray the ground after the Round Up kill, then again after you till the soil for planting, and again after you plant your plants. Use Treflan for grasses and Surflan for broadleafs, being sure to follow manufacturer’s instructions.

But if you want to remain organic and can wait a season, there is another way. Till the area then cover with black plastic to super-heat the soil. This should kill most all of the weed seed after one season. After about a month, plant a cover crop of wheat and fertilize and till into the soil to give organic matter. You will be able to plant the following season.

QUESTION: “I have ordered some Green Giant Thuja and I’m looking forward to seeing them on my landscape. I have researched several Web sites that give width ranges for the GGT of anywhere from 8 ft. - 20 ft. Exactly how wide will it get? I want to plant it near my property line (as a screen), but don't want to invade my neighbor's space. If I plant it 4 ft in, that would allow an 8 ft diameter and still be within the property bounds. Is it possible to regularly prune the GGT in order to maintain an 8 ft width? I'd only be able to trim it up to 10 ft high. Will it get much wider towards the top? I am very excited about how high it will get, but quite nervous about how wide it will get!” – Michelle Goldberg

ANSWER: Yes, Michelle, your information is correct regarding the potential dimensions of the Green Giant if left to its own devices! You can keep them trimmed to the desired width and height with very little maintenance and no ill effect. Topping at the desired height will only serve to thicken the foliage and this will add to the lush beauty of your Green Giant Thula. Good luck with your new plants and if I can be of further assistance please e-mail me again.

QUESTION: “Last spring I planted a number of young Yashino Cherry Trees and they all made it through the winter and seem healthy enough, but they did not flower. (They are profusely putting forth leaves.) These trees were 3- 4 ft tall and bare root when I got them, and I am wondering if perhaps it is normal for them to not bear flowers during the early years of their existence?” – Russ Greenfield

ANSWER: A lot of times in the early years, we fertilize the plants to make them produce vegetative growth which is what your trees are doing now. The more we fertilize the more vegetative growth happens. Once you cut back on the fertilizer, or at least wait for them to bloom in the spring before applying fertilizer, you should see the desired results.

The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to [email protected] and for resources and additional information, or to subscribe to Steve’s free e-mailed newsletter, visit www.landsteward.org