Q: My grandmother’s Christmas cactus has been terribly neglected. I am trying to keep its remains from dying; I have some leaves laying flat on paper towels. — Sandy Schierling, email
A: Christmas cactus is a remarkably resilient plant. Try sticking each individual leaf section halfway into a plant saucer filled with moist potting soil. Make a tent of clear kitchen plastic wrap to go over the leaves and saucer to keep humidity high. Unless the leaves are absolutely dry and limp, you may be surprised that they make roots and put out new growth by spring.
Q: I want to acidify the soil around my azaleas and hydrangeas. How much alum do I use? — Robert Gambino, email
A: It all depends on what your current pH is and whether your soil is sandy, loamy or clayey. You'll need more alum to reduce pH in clay soil than in sandy soil. For a quick example, if you have clay soil plus a current pH of 6.0 and you want to drop it down to pH 5.0, you'd need 19 pounds of granulated or powdered alum per 100 square feet. It might be cheaper to use powdered sulfur. In the example above, you'd need only 3 pounds of sulfur. I have a handy chart that makes calculations easy at bit.ly/lowerph.
Q: I have some acreage that I am considering using as a nursery. I would like to sell plants commercially, but I am not sure where to start. — Steve Payne, Cumming
A: You are just in time to attend the annual conference of the Georgia Green Industry Association (ggia.org) Jan. 25-27. They will play host to 200 friendly vendors and several presentations by nursery experts. Spend a day wandering the show floor and visiting with people. Make notes on what plants seem within your ability to grow, and which ones match your site. Good luck!
Q: I have built 12 raised beds out of concrete blocks. What is the best soil to use to raise flowers and vegetables? — Marinda Tsahakis, Atlanta
A: You have several choices. One option is to use the existing soil (plus some from nearby) and mix in organic matter and coarse sand. The drawback is that you might not have a good feel for how much amendment to add. Another option is to buy pre-mixed bulk topsoil from a reputable vendor. A third option is to fill your beds with bagged soil. There are huge differences between these choices, so I've consolidated the information at bit.ly/bedsoil.
Q: When is the best time to prune sweet olive shrubs? Mine are 6 feet tall and bloom in spring and fall. — Royce Stanford, Suwanee
A: I’d do it after the spring flowering period. Tea olive, Osmanthus fragrans, blooms on twigs that grew in the past six to nine months. By pruning in spring, there’s plenty of time for new growth that will perfume the neighborhood in fall.
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