GARDENER'S MAILBAG

Harsh winter damages some perennials

By Neil Sperry | Published Wednesday, May 21, 2014

Dear Neil: My oleanders have frozen clear back to the ground. Will the tops green back up again? I see new sprouts coming up. Should I cut off the tops?

This past winter was brutal to several types of plants, oleanders included. Yes, cut them off near the ground and let the new shoots become the new stems. The plants will be vegetative (non-blooming) for a year or two. Hopefully future winters will treat them better.

Dear Neil: What causes these rusty colored spots on my maidengrass? Someone said it was fungal and that I’d need to remove all the old leaves this winter, which I did. However, it’s back.

This is indeed fungal, Miscanthus blight. You got rid of most of the source of overwintering spores, but obviously there were still others left behind. Apply a labeled fungicide at once. It won’t help these leaves to green back up again, but it should stop the spread of the disease to new leaves.

Dear Neil: Our variegated Chinese privet seems to be dying. Part of it was brown last summer, and now it appears the winter got more of it. Should it be replaced?

It’s rare for variegated privet to be hurt by Texas cold, but with the drought as a beginning, then the really bad winter, I suspect the one-two punch took its toll. You could try trimming it back, to see how much regrowth you’ll get. Or you may want to replace it with something a bit more dependable. It has other issues (white flies, instability of its variegation, etc.)

Dear Neil: The photo is of a spot that is developing in our St. Augustine. Several other spots seem to be enlarging. What caused it?

Your photo just shows dead runners and blades, so it’s very difficult to get much of an idea of what might have killed it. Unfortunately, between chinch bugs in hot, sunny spots in summer, grub worms almost anywhere and Take All Root Rot in late spring, it’s hard to pick through them. A photo of grass that still has active symptoms would be really helpful.

Dear Neil: I’ve attached a photo of my crape myrtle. There are a few branches in the middle of the tree that have not leafed out. The wood seems to be green, however. We have never pruned them in the 13 years that we’ve had them until last year when we cut the tops (but not by much). Why is this happening?

I can’t tell from the photo if the branches that aren’t leafing out are directly associated with the fairly major cuts you made last year. That may very well be the case, as topping weakens crape myrtles. However, the other branches have strong new growth, so you’ll be fine in the long run.

One thing I might suggest after seeing your photo would be that you look critically at the trunk to the left. It looks like it’s growing into and around the two-branched trunk to the right. It also looks like one or both of those dead shoots at the top might be associated with that left trunk, all of which leads me to suggest that you might want to remove the left trunk entirely to the ground.

Dear Neil: My new Turk’s cap plants that I set out last year have not come back so far this spring. They were beautiful last year. Should I just assume them to be lost to the winter?

Yes. It’s time to replant. Established plants that are several years old probably would not have suffered this setback. Try again. They’re great plants. They are rarely affected by Texas cold.

Dear Neil: We have an old family peach tree that probably dates back to the early 1920s. It has emotional importance to all of us. It has died to the ground, but new shoots are coming up from the roots, and they are 15 to 20 inches tall. What can I do to keep it thriving?

Understanding completely that this is for sentiment and not for bounties of produce, the best thing you can do is to allow those shoots to develop for several months. When they are 30 to 36 inches tall, select three of them that are equally spaced and quite vertical. Pinch the growing tips out to force side branching to begin, and you should be back in business.

Dear Neil: Why are my rose buds turning this dried brown color?

Thrips. Peel one of the buds open, and you’ll see dozens of tiny whisker-sized insects moving around within the bud. They suck the very life out of the flowers. Apply a systemic insecticide to the soil to prevent them in the future. You need to allow a couple of weeks for the product to be taken into the plants and up to the buds, so apply it as the buds start to form.

Dear Neil: What is the best product to apply to St. Augustine to help it grow vigorously? When should I apply it?

Most Texas soil tests show that we need to use only a high-quality nitrogen fertilizer – one with half or more of its nitrogen in slow-release form. Because gray leaf spot can be a problem for St. Augustine during the summer months and because gray leaf spot is accelerated when nitrogen is added, you should fertilize in mid-April, mid-June and early September.

Since you missed the April feeding, I would fertilize soon, then wait until early September for the next feeding. Apply the fertilizer at a time when you will be able to water or when a moderate rain is expected. (It’s always better to fertilize before you run sprinklers, instead of relying on rain. That avoids the chance of runoff. However, in this year of curtailments, it’s difficult for some gardeners to do that.)

Have a question you’d like Neil to consider? Mail it to him in care of the Wise County Messenger, P.O. Box 149, Decatur, TX 76234 or email him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.

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