Q. Dear Neil: We have six 100-year-old live oaks on our property. We’re about to do some landscaping that will include an irrigation system. What do we need to know to avoid harm to the trees?

A. Be thankful that you’re dealing with live oaks and not post oaks. Live oaks are quite tolerant of what we do around them. Post oaks are a different story. I’m assuming you have hired a licensed irrigation contractor to do the work for you. That person will be well versed in installations around live oaks, but the main thing is to keep root cuts to a minimum. Think of any given tree’s root system as an old-fashioned wooden wagon wheel. You want to cut trenches between the “spokes” (roots) and not across them, even if it means longer runs of pipe. Do not change the grade by adding soil over the roots, and resist the urge to use the system to excess.

Q. Dear Neil: My wife received this plant (see photo) four years ago when her father passed. It has grown so tall that it’s now touching our ceiling. This is a west-facing window. Can it be cut back, and can the portion that’s cut off be planted to make a new plant? How do we do it?

A. You have a Janet Craig dracaena – one of the best houseplants ever. Yes, it can definitely be cut back. In fact, I’ve done so with several that I’ve had over the years. March or April would be the best time to do so since the plant would be gearing up for new growth as the light grows stronger and the days grow longer. If it were mine I would trim it back to 12 or 18 inches and repot it into the next larger pot size with fresh potting soil. Take the long stem that you’ll be severing and cut it into sections each containing a couple of leaves. Leave one leaf on each section and cut the remaining leaves to remove two-thirds of the leaf surface. Stick the cuttings into 6-inch flowerpots filled with a mix of equal amounts of sphagnum peat moss and horticultural perlite. Keep them moist and bright and they should form roots within a couple of months. There are dormant buds along the stem, and those will form new shoots as the roots start to form.

Q. Dear Neil: What is the best time of year to trim rock roses and regular bush roses?

A. Rock roses (Pavonias) are related to hibiscus and should be pruned lightly all through the growing season to keep the plants tidy and compact. Shape them in early spring just as new growth begins as well. Bush roses are pruned in early February before new growth commences. Each cut should be made just above a bud facing out from the center of the plant. Aim to cut the plants back by half.

Q. Dear Neil: What are the best types of fruit trees for gardeners with limited space? How available will they be?

A. Methley plums are excellent over big parts of Texas. Orient pears are as well. They are also attractive ornamental trees, so they can perform double duty in the landscape. Figs make attractive large landscaping shrubs. All should be fairly readily available.

Q. Dear Neil: For several years I’ve had a Meyer lemon tree and a kumquat tree planted near one another. This year the lemon has stopped bearing fruit and seems to have grafted itself onto the kumquat (see photos). Now the kumquat is bearing both kumquats and lemons. Is that normal?

A. I’m trying to figure things out. Meyer lemons are grafted onto other citrus rootstocks. Your photo showing the two trunks growing out of one another really looks like a rootstock that is taking over because a top growth has died or weakened. That might mean that you have some type of sour orange rootstock. But as I said, I’m confused and actually just guessing.

Q. Dear Neil: What has happened to my Green Cloud Texas sage? They have been watered by drip irrigation for 30 minutes every day for the past four years, but this year for the first time many of their leaves are turning yellow.

A. I see in your photo that the yellowed leaves are all older leaves. There has been significant new growth at the ends of the branches. That tells me that the plants probably got too dry back in mid-summer, although I don’t know how they could have gotten dry with such frequent watering. You shouldn’t have to water any shrubs daily, let alone Texas sage. But I do think the drought took its toll on your plants. They should be fine by spring. You might want to consider a heavy shearing in late winter to force new growth to fill along the bare stems.

Q. Dear Neil: In taking out my ornamental sweet potatoes I have discovered huge roots. Are they edible? If not, can I save them for replanting come spring?

A. They are not edible. They’re extremely fibrous and tough. And they’re not usable as a source of new plants for next spring. You’ll want to start with new transplants that are healthy and vigorous.

Have a question you’d like Neil to consider? Mail it to him in care of this newspaper or email him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.

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