In the high heat of the summer, there really are very few plants with any flowers to speak of. I think that psychologically, it's so important for us to have flowers around us. Well now, since many of us have made the switch from high water using plants to more stark desert landscaping, we need to be creative about getting our flower requirements met. We love the spring, when all the cacti and so many other plants put on a terrific display of colors, but who talks about summer flowers in the desert southwest?
Sure, you'll find flowers on your Palo Verde, and desert willows might still have a few, but those are trees. Even if the red yucca blossoms aren't completely past, they soon will be. There's a fair number of attractive plants that you can select for dry land, or water smart landscaping, or xeriscape (whatever you choose to call it), but among my favorites is lantana. This is a relatively low growing, kind of sprawling, shrubby plant. I believe that it's a terrific addition to gardens here. In some parts of the country, it's planted in the spring and it grows vigorously until the temperatures drop in the winter. Lantana's sensitive to a hard frost, but it's not extremely delicate. It's rarely bothered by our winter temperatures, so you can plant it as a perennial.
Here's a shrub that will not only withstand our terrible salty soil, and lack of rain, and blistering sunny temperatures, but it thrives in our conditions with only a little help! The plant doesn't merely survive, but it produces flowers through the summer and fall as well. Butterflies like the flowers, so if you're interested in a butterfly garden, lantana and vitex should give you a terrific display.
The flowers are interesting, ranging from bright orange yellow, to yellow rimmed with red. Some even have lavender flowers - very attractive, since so many desert plants produce flowers only in yellow.
All told, there're about 150 different species of lantana, not to mention all the hybrids and cultivars. We only see a few of them, so I don't know what some of the more exotic ones look like. I do know that the species we usually get is Lantana camara. I did find a Texas website that mentioned a Lantana horrida, which refers to the smell of the leaves when crushed. I decided I wasn't going to check it out personally.
In Florida, Hawaii, Texas, the Galapagos Islands - and other areas where the temperatures are high, the soil is fertile, and water is available - common lantana's become a horticultural escapee from gardens into other areas, and it's now considered an 'invasive exotic species'. That means it's a bad weed in those places.
Many of the plants we grow produce dark, almost black, berries when the flowers are past. These berries contain seeds, which is the way that many of the invaders became established. The berries are also known to be quite poisonous, although quite a few birds appear to like them. Plant breeders have developed a number of sterile cultivars, which bloom longer, and don't contribute to the weed problem. They flower in a wider range of colors than the old lantana does - including white and pink.
I said before that this is a drought tolerant plant, that it can survive a lack of rain. Of course, that doesn't mean no water. Infrequent, deep irrigation will help it grow more luxuriantly.
You might notice that here at Cooperative Extension, we often recommend infrequent deep irrigation. That encourages the roots to grow thick and deep, giving the plant better support and a better chance of finding water and nutrients in the soil - this isn't just for lantana, but for many other landscape and garden plants. And while lantana does grow in our problematic soils, it will benefit from fertilization - try watering it in the spring with compost tea, or putting compost around the base early in the season. Don't go overboard with nitrogen during the summer, though, since that could interfere with flowering.
Lantana's a tough bird. It's not bothered by many insects, and there aren't very many pathogens that affect it, either. What it doesn't like are cool shady spots. When it's placed in deep shade, that's when it's more likely to develop diseases. You can save those places for the more delicate low light plants that you'd like to try.
Finally, the best time to cut it back is in late winter, before it starts to produce new leaves. At the end of January, you can cut it down to eight inches or so. Yes, it will look very dramatically shorn. It will grow back. And be even more lovely.
For KNPR's Desert Bloom, this is Dr. Angela O'Callaghan of the University of Nevada Cooperative Extension.