Herbs need a little afternoon shade in South Texas to grow well

Q: I love to grow herbs, but my apartment balcony faces the hot western sun. Plants wilt every day, and they don’t do very well. What could I do?

A: There must be some easy and affordable way to erect temporary shade protection. Perhaps it would be a piece of nursery shade fabric secured in place. It is sometimes sold online and in stores in pre-cut and bound small sizes.

Perhaps you could have a tall and slender potted plant, perhaps a fairly upright juniper, or maybe a large pot with an attractive wrought iron trellis covered in an annual vine — just some means of breaking the sun. A few herbs can handle that kind of full-sun exposure, but most would benefit from any shading you could provide.

Q: We have four raised beds about 15 feet by 6 feet in which we plant various vegetables each year. We rototill and add fresh compost from our own pile each year along with fertilizer.

Is it necessary to rotate the crops that we grow around in those beds? We have not been doing that, and our yield has reduced over the past two seasons. Or could it just have been the crazy weather cycles we’ve been going through?

A: Texas is known for its “crazy weather cycles,” so we might as well get used to that. Some crops (legumes such as beans and peas) enrich the soils in which they are, while other crops deplete the soil of much-needed nutrients. Rotating the crops will help even that out.

However, the possibility of soil-borne challenges from diseases, nematodes and even insects looms even larger. Crop rotation, wherever it’s feasible, is always a good idea. But you need to know your crops and their plant families. It won’t help to rotate closely related crops with one another.

Peppers, tomatoes and eggplants are all sisters. So are cucumbers, melons, squash and gourds. Broccoli, cabbage, Brussels sprouts, cauliflower and other Cole crops are in another group.

Finally, all of that said, you are absolutely correct on the weather issues. If you have repeated cold spells in a spring, it can throw planting dates off badly. Plant vegetables too late and they will frequently end up with very poor yields.

This lorapetalum us an unstable cultivar that suddenly went from deep pink to white.Courtesy photo

Q: I’ve had my lorapetalums for years, and I love it when they bloom. Why would one of them throw out a white-flowering branch? I think I recall it doing this one other time.

A: It’s an unstable cultivar. That’s a mutation, and it’s how new types are discovered. Odds are that it has all the same genes as the rest of the plant (same height, growth form, etc.), just not with the same color.

The question now would be if it would remain stable. We used to have a crape myrtle cultivar called Snow Baby. It probably still exists out there somewhere — a lovely white, semi-dwarf type, but it has the awful habit of reverting to lavender. You’d plant a bed of Snow Baby, and before long you’d have a bed that was half white and half lavender.

Q: I have about 98 percent of a container of Epsom salts left over. It has long since gone past its “use-by” date. Can I still use it on my plants? How would I use it, and for how long? What does it do for the plants?

A: Epsom salts are a source of magnesium when soils are deficient in it. However, that rarely happens, especially in soils that have any content of clay. I don’t recall ever feeling the need to recommend it to a reader or radio listener. Most Texas soils have ample supplies. As for how long it would be good past its “use by” date, a smarter chemist than I will have to advise you.

Q: My Blue Rug junipers died back last year. I’ve cut out the dead wood now, but there are bare spots left behind. What kind of fertilizer would be best to get them to regrow?

A: Apply an all-nitrogen plant food. Typically, a high-quality one with half or more of its nitrogen in slow-release form would be best, but as a one-time treatment, ammonium sulfate (21-0-0) might jump-start your plants into vigorous growth this spring.

It would be best to supplement that one month later with a higher quality all-N product. Watch out for spider mites from here on out. They are often the cause of browning and thinning of trailing junipers.

Q: We have property in Central Texas that has many nice, large post oak trees. Over the past five years, we’ve lost several. When I cut one down, I found several large boring types of beetles inside. What can I put on the trees so that I won’t lose any more of them?

A: You really need to get a certified arborist on-site to look at your remaining trees. Post oaks, more than any other type of tree that we encounter, can look good one month, then be almost dead six months later. Often, it’s environmental stress (grade changes, compaction, drought, excessive water, etc.), and other times it’s just old age. Their life expectancy probably averages 75 years.

It’s rare for borers to attack a post oak without some other, bigger problem weakening the tree and “inviting” them in. The extreme drought of 2011 may still be taking its toll on post oaks. It was awful.

Q: You mentioned applying a weedkiller, and that it would take about two weeks to do its job. How long do I have to wait to fertilize my lawn? What is the sequence?

A: Broadleafed weedkillers (containing 2, 4-D) typically take 10 to 15 days to kill weeds like dandelions, clover and thistles. They work best when they’re applied to strongly growing foliage.

Therefore, the sequence: mow, apply fertilizer on a day when you can water deeply, wait a week and mow again, wait three or four more days, then apply your weedkiller. Wait a few more days before you mow again.

Email questions for Neil Sperry to SAENgardenQA@sperrygardens.com.

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