Dear Neil: We have bluebonnets planted and growing in an area where we are going to plant El Toro zoysia sod later this spring. We will wait for the bluebonnets to go dormant before we lay the sod. Will they come up through the grass next spring? Also, how can we eliminate clover that is there before we plant the sod?
A: Wildflowers, and in this case more specifically bluebonnets, do not coexist with turfgrass at all. If you think about where you see bluebonnets growing natively, it’s always in an area that has poor soil with little native pasture grass. Bluebonnets succeed in bare areas, but they struggle competing with dense grasses. The highway department plants them in roadside areas that do have grass, but it’s not strong, assertive grass like you’d have in a lawn. In fact, you’ll notice that many of those wildflower slopes along highways are pretty bare once they mow off the old, dried bluebonnet stubble in early summer. My advice would be to let the bluebonnets run their course, then gather the seeds just as the pods start to split open. Store the seeds over the summer in a jar or plastic bag (without moisture), either in an air-conditioned part of the house or in the refrigerator. Sow them into an appropriate place in late August or early September. A dedicated bed that receives little “heroic” soil preparation and that is seldom, if ever, fertilized would be great. As for the clover, once you have the bluebonnet seeds collected, rototill the area before planting the sod. The tilling will eliminate the clover.
Dear Neil: My husband and I want to put down some type of hardscape surface around a red oak tree. How much space should we leave between the trunk and the hard surface?
A: The more you can leave, the better you and the tree will both be — but at least 3 or 4 feet out from the trunk. Trees’ major lateral roots are near the soil surface, and as the tree ages, those roots grow up and out of the soil. It’s not due to erosion. It’s just that they get large. As they swell, they break the hardscape surfaces. That’s why interlocking concrete pavers and other “portable” materials are so useful when working around trees.
Dear Neil: Why do the seedlings I start under grow lights for my flower and vegetable gardens end up getting so tall and spindly? They don’t survive the transition to outdoor planting? I have lost them all.
A: That breaks my heart when somebody has that kind of experience, and unfortunately, you’re not alone. This can be due to a couple of things, and I can best illustrate by telling you how a bedding plant grower will produce his or her plants. They will grow them in absolutely full sunshine, and they will grow them at 60 or 62 degrees. Grow lights provide perhaps five percent that amount of light, so the plants become lanky as they “grow toward the light.” That is made much worse very rapidly when temperatures are warm — they try to grow more rapidly. You’d be better off investing in a small cold frame or, better yet, a home hobby greenhouse or window greenhouse that would give you more light.
Dear Neil: I have a 60-foot hedge that has gaps in it. It is 8 feet tall. Is there any way to prune the plants to get them to fill in?
A: Oh, how I wish I knew what type of plant was involved, also whether plants in the row actually died, or what else might have happened to cause the empty spaces. Sometimes you can find the same type of plant in a large nursery container and plant it into a void to solve the problem. Of course, if the gaps happened because a sprinkler head didn’t water that part of the row (to use one example), the new plant would suffer the same fate. There are too many variables for a good answer. I’d suggest you take a sharp photo (print, not on phone) to a local independent retail nursery for their suggestions. They can show you the replacement plants for the voids, if that becomes an option.
Dear Neil: We have several acres of wildflowers, and they are the joy of every springtime. Unfortunately, they are now being invaded by the horrible purple thistle. How can I control that plant monster?
A: If you’re talking about the tall, coarse-growing thistle with very prickly leaves, you can carefully spray its growth with a broadleafed weedkiller applied individually to each clump. Obviously, any herbicide that kills thistles will also kill desirable wildflowers. They do not differentiate. It’s also possible that you are calling the invasive Scabiosa atropurpurea (pincushion flower) a “thistle,” although it is not prickly. Again, since it’s not a grass, selective spraying with a broadleafed weedkiller before it has developed strong colonies would be your best bet. You may want to talk to your local county Extension office for more precise advice on the invasive plants that might be called thistles in your immediate area. There are many types across the state.
If you’d like Neil’s help with your plant question, drop him a note to Gardener’s Mailbag, P.O. Box 864, McKinney, TX 75070 or email your questions to firstname.lastname@example.org. Watch here for his reply.
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