Q: I have a large, happy forsythia. It is probably ten feet across but I would like to prune it. Any recommendation on when and how? Steve Smith, West Cobb
A: Now is the perfect time. The plant will have plenty of time to grow new branches and flower buds before winter. I'd prune it to half the size you want it to be next spring. I have a shrub pruning calendar at bit.ly/shrubpruning.
Q: I'm moving from New Mexico to Alpharetta in a few weeks and just received a beautiful Goldfinger cinquefoil plant as a gift. Am I allowed to bring it in the state? Jennifer Peters, email
A: We are all excited to hear of your (and your plant's) arrival. Unlike Florida and California, which have stringent plant-importation rules, to my knowledge there is no law governing inspection of homeowner plants when moved into the state. Our laws govern plant dealers and growers, who are regulated and inspected for disease and insects. Cinquefoil, Potentilla fruticosa, tolerates cold very well but I'm not so sure it will like our heat. Site it where it gets morning sun and afternoon shade and see what happens.
Q: I started some onions from seed this fall. They are Red Delicious Hybrid from Burpee. They are doing well, however I now see them beginning to form flowers. Should I cut off the flowers at the bottom of the flower and have the plants continue to grow? Brian Hills
A: Did you note on the Burpee label "Well suited for the northern gardener?" The number of daylight hours is critical to the development of onions. It tells the onion when to begin producing a bulb. Varieties with certain day-length characteristics grow well in certain areas of our country. Long-day varieties are best in Northern areas. I think yours is a long-day onion that has decided to go to seed early. Short-day varieties grow best in Southern areas. If you like red onions, 'Red Creole,' 'Southern Belle Red' and 'Red Burgundy' are best for Southern gardeners. At this point, cut off the flower stems and chop the leaves for scallions.
Q: A vehicle struck a water oak tree in our yard yesterday. There are several deep cuts in the bark. Is there anything we should do to the tree to make sure it survives? Angie Dobbs, email
A: Use a razor knife to remove any loose bark or splinters near the wound. Spray the exposed wood with water-based insecticide to deter borers for a few months. If things go according to plan, the tree will slowly grow callous tissue over the damage.
Q: I read that the purple fountain grass I planted last year will not come back this spring because it freezes in winter. I really like the way it looks but can't afford to plant it every year. Is there something similar that comes back every year? Brian Smith, Watkinsville
A: Purple fountain grass is indeed a beautiful plant! Its seeds are sterile, so you're confined to buying small plants as they become available in spring or dividing a large nursery plant into several small clumps. I have a couple of alternatives for you. Switchgrass, Panicum virgatum, has several cultivars with varying degrees of red or purple in the foliage. Consider 'Shenandoah', 'Heavy Metal', or 'Cheyenne Sky.' Muhlygrass, Muhlenbergia capillaris, has beautiful pink seedheads in fall. Look online for pictures of these plants to see if they suit your wants.
Q: I bought several pots of Mexican heather but I'm afraid the soil may not drain well enough where I plan to put them. I read on your website to add "organic soil conditioner" but I don't know what that is. Lori Gunn, Clay County AK
A: You're right to be concerned about soil drainage for Mexican heather. It originated in Guatemala and Mexico, so it loves summer heat and sandy soil. Soil conditioner is simply shredded and composted organic matter, like landscape trimmings and wood fiber. You should be able to walk into any independent nursery and find their bags of soil conditioner with little help. To make a bed of fast-draining soil, I place a 3-inch layer of soil conditioner eight inches deep and follow that with an inch of gritty sand (not play sand) mixed thoroughly with everything else. Mix some slow-release fertilizer (Osmocote, Dynamite, etc.) into the planting hole, water occasionally, and you'll have summer-long, flower-producing, butterfly-attracting machines!
