Q. Over the past few months, I have redone my garden, amending the soil, planting new plants and so on. There were several old rose bushes that I kept, but two of them keep sending up long, vigorous shoots and the bushes don’t bloom. I can’t figure out what’s going on. Could it be because they were neglected for a while, or could it be that they were previously in partial shade but now are in full sun? I don’t want to give up on perfectly healthy plants, but I want them to bloom if I’m going to keep them.

Almost all roses are grafted onto hardy rootstocks. The scion (top part) of the shrub produces those pretty flowers, but on their own roots, they are fussy little princess plants. Grafting gives them some resistance to diseases and soil-dwelling pests.

Rootstocks, especially “Dr. Huey” and “Odorata” tend to sucker, sending out long, vigorous branches that look different from the top branches. “Dr. Huey” is popular in California, where most roses are commercially produced. If you see long, vigorous branches growing out of the lower part of your rosebush, especially if they have red, single-petal flowers, remove them before they take over the whole bush.

Sometimes the rosebush will die at the graft and the rootstock will take over, leaving you with lots of happy-looking branches and no or very few flowers. Occasionally, overenthusiastic pruning will give the same result.

In either case, if your rosebush is healthy-looking but not producing flowers (or at least not the flowers you wanted), it may be time to dig them out and replace them.

Q. The leaves on my Tibouchina tree, which is only 5 feet tall, wilted suddenly. We live in Orlando, Florida. I’ve been watering it regularly. Any ideas? 

Tibouchina trees are small trees or shrubs that bear beautiful purple flowers. They are popular in southern Florida and do not tolerate frost or wind. They also don’t like full sun and do best in a semi-shaded location. They only reach 15 feet but tend to have a sprawling habit unless pruned to a single trunk form.

If you move to Florida but miss some of California’s landscape trees, tibouchinas look like a mini version of jacarandas.

Usually, when a plant’s leaves suddenly wilt, it’s caused by overwatering and/or poor drainage. Florida’s soil is very sandy, so drainage should not be the problem here.

If the tree is a recent planting, it’s roots may not have spread enough to tolerate an especially hot day or missed watering.

For my Florida readers (many are, no doubt, California transplants), check out the University of Florida Master Gardeners at Florida Master Gardener Program – UF/IFAS Extension (ufl.edu).

Looking for more gardening tips? Here’s how to contact the Master Gardener program in your area.

Los Angeles County

[email protected]; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/

Orange County

[email protected]; 949-809-9760; http://mgorange.ucanr.edu/

Riverside County

[email protected]; 951-683-6491 ext. 231; https://ucanr.edu/sites/RiversideMG/

San Bernardino County

[email protected]; 909-387-2182; http://mgsb.ucanr.edu/