A beautiful, undead gardenia. No, that doesn't make it a zombie. Photo: Steve Bender

Welcome to Throw-Down Thursday, that sacred time we take each week to answer your most pressing gardening questions with honesty, sensitivity, insight, and -- most important -- the 1001% correctness you've come to expect. Let's get right to it.

Question: My gardenia was frozen this winter and the leaves are still brown. When should I prune off the dead stuff? Miley

Answer: For gardenias and many other broadleaf evergreens (loropetalum, bay, Encore azalea, Indian hawthorn, etc.), winter came in like a wrecking ball, Miley. They're not used to that kind of cold in the South. What you should do now (besides putting on some clothes) is scratch the bark of your gardenia's branches to see if you can find green underneath. Green means that part of the branch is still alive. Prune back each branch to the topmost point where you can find green.

emCommon chickweed, a cool-weather lawn weed. Photo: Steve Bender/em

Question: When should I put down weed-and-feed on my lawn? Bilbo

Answer: If it were up to me, never. I don't like granular weed-and-feed products, because most people apply them at the wrong time, so they don't work. Garden centers start selling the stuff about Valentine's Day (what a lovely gift for a beautiful lady), but for it to work, weeds need to be actively growing. So you need to wait until at least May. Plus, the granules need to stick to the weed leaves for 24 hours so that the weed-killer is absorbed down to the roots. If they tumble off or it rains before then, the weed-killer is useless and you end up feeding weeds. Now I have a question for you, sir. Is that real grass on your roof or the plastic stuff?

em'Knockout' rose. Photo: Steve Bender/em

Question: When I can prune my 'Knockout' roses? They've gotten really big. Adrienne can't see over them no more. Rocky

Answer: Yeah, most people don't know that 'Knockout' rose can grow at least 5 feet tall and wide over time. Fall into that thorny beast and you'll be down for the count. The good news is that you can prune it back to the desired height at almost any time and it will still bloom. But because its first spring flush of bloom is the showiest, wait to prune until after that finishes. Wear gloves when you do. If you forget, I know a good cut man.

emNasty, evil fire ants. Photo: Marufish/em

Question: In a recent Southern Living, you described a new product called Ant-Zap that uses carbon dioxide to kill fire ants. But when I went to the website, it said the product was for carpenter ants, not fire ants. Don't you check your facts before you go public? Lara

Answer: Of course I do, Lara. In fact, I use the same fact-checker who works for 60 Minutes. Here's my excuse. Some guy sent me information on a new natural, non-chemical product to kill fire ants. I was interested, because I didn't know of any effective non-chemical control (despite what you've heard from your mama, grits don't work). So I wrote a little blurb about the product, but emphasized I hadn't tested it. Then people started emailing and complaining the product isn't recommended for fire ants. What can I say? The manufacturer shamefully misled Grumpy. Then a reader then wrote in with this great tip. An easy way to suffocate fire ants using carbon dioxide is to pour a bottle of club soda on the mound. The store brand will do.