What’s happening to winecups?
The plant is decaying from the center outwards, and the leaves turn yellow and have bumps on the undersides.
And right after we received this question, I noticed that the winecups in the garden in front of my office are doing the same thing. We have a huge patch of them, about 4’ in diameter, and death is slowly radiating from the center, ever closer to the edges of the plant. The viewer suspects she has rust. And we thought she might be right. But rust or not, we knew that this was most likely caused by some sort of microbial pathogen, so we consulted my good friend Dr. Kevin Ong, Extension Plant Pathologist from the Texas Plant Disease Diagnostic Lab. Dr. Ong confirmed what the viewer’s initial research led them to believe: rust. And he says that he’s seeing reports of lots of it this year. Now for the not-so-great news: Unfortunately, there really isn’t much to be done for the plant at this point. Fungicides may be successfully used on rusts in many cases, but here, with the entire center of the plant already dead, you won’t be able to reverse the damage, so you needn’t bother with any treatment. This disease is likely a little more prevalent this year due to the fact that we had a relatively warm winter, with better than average rainfall, and our spring temperatures warmed up very early. Because of this, our wildflowers came on early and strong, and microbes took advantage of the warmer, wetter than normal, environment. I would suggest allowing the plant to flower until it becomes more unsightly than you can bear, then cutting the top-growth back. Winecups are perennials, so they should grow back from their underground tuber, if it hasn’t been damaged by staying overly wet. Winecups prefer dry, rocky, very well-drained soil, so if you have organic mulch around them, be sure to remove it. After you’ve cut the plants back, clean up any organic matter, including any mulch that you had around the plant. Rusts are very host-specific, meaning that each species of rust usually only attacks a couple of specific plants, so the rust on your winecups most likely won’t damage the other plants in your garden. Dr. Ong also pointed out that the rust was most likely only the initial pathogen, after it did some initial damage, other pathogens most likely moved in to take advantage of the weakened plant. So be sure to remove all of the possible source of pathogenic spores that you can and toss it in the garbage.
Pruning Spring Plants. What can we prune now? And should we fertilize plants that just finished blooming?
Well, pruning can be a tricky subject, and the key to pruning is knowing your plants growth habit, and understanding how pruning affects each plant. Most trees should be pruned in the winter, but if your deciduous tree struggled in last summer’s heat and you were waiting until they leafed-out to see which areas were truly dead, you can go ahead and prune out any obviously dead growth now. Be sure to use pruning paint on any oaks that you prune right now—with temperatures warming up, the possibility of oak wilt infection is increasing. Shrubs, especially those that require hedging, should be pruned now, before temperatures really heat up. Be sure to use nice, sharp shears when pruning hedges, so that you make a clean cut—you don’t want the tops to have torn leaf edges that not only look unsightly, but also heal less quickly and serve as an open door for disease pathogens to move right in. If your spring flowering bulbs and perennials have finished flowering, you can go ahead and clean those up a bit to encourage them to put on a flush of new growth, and perhaps even flower again, depending on each plant. And if you have any plants that bloom all summer but have started to slow down a bit in the heat, a little dead-heading, to remove spent blooms, will encourage new blooms to form faster. It’s also a great idea to give a light dose of fertilizer to plants that have just finished blooming. Flowering and forming seeds takes a lot of energy, and replenishing some of a plants nutrients, so that it can rebuild its own body after having given so much of its precious energy to the next generation, is a good idea. But just a light dose. We’re coming in to the heat of summer now, and you don’t want to encourage your plants to grow too much at such a stressful time of year.
Why are fall-blooming plants flowering in spring?
Well, as is often the case with plants, weather is a key factor in their growth responses. Many temperate zone plants mark time with environmental cues. When the number of hours of sunlight begin to get shorter and temperatures begin to cool a bit, that means winter is on its way—a cue to plants that they should begin preparing for dormancy. And when the hours of daylight begin to increase and temperatures get warmer, plants begin preparing to wake up for spring. But when the weather patterns fall out of this norm, cold in winter and warm in spring, the internal time-keeping mechanisms of plants get confused. This past winter, we were abnormally warm and wet, with a lot of cloudy days. To many of our fall-blooming plants, this weather seemed more like Autumn than spring, and so they thought it was their normal flowering time. I noticed lots of fall asters blooming around town. If your fall-blooming plants bloomed this spring and you’d like to encourage them to bloom again in the fall, be sure to give them a good shearing to remove the spent blooms and encourage new buds to form. They’ll likely stop blooming over the summer, but when our nights start to cool a bit and our days begin to get shorter, they should fall back into their normal autumn-blooming habit.
Best way to mulch?
Viewer said “I’ve always heard that mulch helps keep moisture in the ground. But, after a 1/2″ rainfall event last year, I was shocked to see that the mulch also prevented the rainfall from penetrating the ground. The soil was absolutely dry after 1/2″ of rain. What should I do this year?”
Because of the extremely hot, dry weather, organic mulch got, and stayed, really dry, creating a sort of crust on top of the soil. So when it rained, the mulch soaked up some of the water, but since it was so dry, much of the water may have run off to surrounding areas because it couldn’t soak in fast enough. The mulch was still doing its job though: protecting the soil from the elements and insulating it to keep it cooler, and keep moisture from evaporating so quickly. So, back to your question of what to do: you should still use mulch, only instead of using the standard recommendation of two to three inches, maybe cut back to only one, so the rain-blocking crust doesn’t get so thick. During extremely hot, dry times, the lack of moisture also keeps the mulch from breaking down at the soil surface and becoming soil-building organic matter for the future. In my garden, I usually just add a one-inch layer of new mulch to the top of last year’s. But this year, I went ahead and removed most of the old mulch and put it in my compost pile before I added new mulch. Last year’s dry, crusty mulch would eventually break down, with enough moisture, but you don’t want to make the layer even thicker by just adding mulch on top. Another helpful thing to do this year would be to add drip irrigation or soaker hoses to your beds under the mulch, if possible. Adding moisture underneath the mulch will ensure that your plants get water directly where they need it. And if you don’t have a compost pile for your old mulch, put it out in paper bags by the curb with your other yard waste, so that the city can turn it into compost.
Celosia spictata ‘Flamingo Feather’, sometimes called wheatstraw celosia
We’ve long admired this warm weather annual in the East Side Patch garden of Philip Leveredge, where it readily sows itself in sunny decomposed granite paths. Philip notes that celosias prefer a well-drained, gritty soil. In fact, they are prone to root rot if kept too wet. At the same time, even though they love the heat, they do require supplemental water in drought. These are showy plants that get two to two and a half feet tall and about 14” wide. The vibrant pink flowers are great for dried arrangements, and you can collect the seed to plant again next year. Plant seeds after the last frost to enjoy until the first freeze. Philip harvests seeds from his plants when they mature in November or December. At that time, he plants them where he wants to see them next year. Or, you can save your seeds in a container to set out in spring.
Mexican honeysuckle (Justicia spicigera)
Although it shares a common name with our common honeysuckle, Lonicera japonica, and looks somewhat similar, the two plants are not related. But Mexican honeysuckle IS related to another great plant for Central Texas gardens: shrimp plant. A viewer moved her plants from a former garden and last year they were a little slow to establish. They’re now quite at home in the southwest corner of her garden where they get shade from a cedar elm. In harsh winters, Mexican honeysuckle is perennial, dying back to the ground. But in our mostly mild Central Texas winters, Mexican honeysuckle is evergreen, sometimes not even being frost-bit, but it will benefit from a bit of pruning in late winter, to invigorate new growth. It can get 2 to 3’ tall and spreads much wider, so give it plenty of space to spread out. It isn’t too picky about soil type, but it does need a little supplemental irrigation, especially if the summer is especially hot and dry. Mexican honeysuckle needs a little sun to put on a nice show of flowers, but it does like to be in a bit of shade and will struggle in too much sun. In mid to late summer, Mexican honeysuckle will put on a gorgeous display of bright orange flowers, which contrast nicely with the deep, velvety green of its leaves. And it normally stays covered with blooms all the way up until the first frost.
Texas star Hibiscus Hibiscus coccineus
This wonderful Texas native is also known as scarlet rose mallow. Although related to the tropical Hibiscus that are found in Hawaii and other warm, wet regions, Texas star hibiscus is quite happy in temperate Central Texas. It grows 3 to 6 feet tall and about 4 feet wide and dies back to the ground in winter. As with other perennial shrubby plants, wait until temperatures begin to warm up in spring and then prune off all of the top growth down to the ground and you’ll begin to see the new growth emerge from the roots. Resist the urge to prune off all the stems in late fall or early winter as soon as all the leaves have dropped off. As the plant is preparing to hunker down for winter, many chemical processes are occurring in those “dead” stems. And, the leafless stems provide a little bit of protection from the cold. Unlike its tropical cousins, Texas star Hibiscus can withstand most of our winters, barring any truly harsh freezes. Be sure to mulch well around the base of the plant to protect the roots from any out of the ordinary cold spells. It can take full sun, but also does fine in part shade, although it may bloom a little less. Texas star Hibiscus can handle wet soils, but works in dry ones, too. Although it will acclimate to our soils and need very little supplemental irrigation in “normal” times, if summer is particularly hot and dry, you will need to water this plant. It spends the spring putting on green growth and then flowers all summer long, attracting a parade of hummingbirds and butterflies to your garden. The flowers are large, off-red, and more open than the showy tropical hibiscus, with 5 very distinct petals. Each flower is only open for a day, but new ones open all summer long. You may notice that the flowers look very similar to another of our great Texas natives, Turk’s cap. That’s because the two plants are in the same family, the Malvaceae. Quite a number of wonderful Texas natives are in the mallow family. In fact, the Lady Bird Johnson Wildflower Center’s native plant database lists 88 native species.
A surprisingly drought tolerant and root hardy tropical vine. We’d noticed a gorgeous specimen of this plant on our visits to The Great Outdoors, so we dropped by to talk about it and snag some photos. Staff says their Rangoon creeper thrives in full sun, with very little water and absolutely no fertilizer. It’s obvious from the trunk size that the creeper at the Great Outdoors has survived quite a few years of harsh Central Texas weather, including extended drought and unusually cold winters. It does need the support of a fence or trellis, so be sure to give it a spot where you can provide plenty of height for future growth. Staff reports that their Rangoon creeper does freeze back if temperatures drop into the 20’s, but bounces back with no problems. The gorgeous, deep-pink and white flowers, which seem to drip from the plant at every possible spot on the plant, resemble those of Plumeria, but aren’t quite as large. We also found this beautiful plant in viewers garden in San Antonio, which we recently highlighted. She says that her creeper only gets a few hours of mid-day sun, so that hampered its establishment a bit and it took about three years to start flowering. But now, it blooms quite well, starting in mid-summer. She waters her creeper about once a week in the hottest part of summer and has never noticed it wilting. And she has never noticed a disease of insect of any kind! And another viewer with this plant, reports that this plant does fabulously for her, and that the flowers smell like a bubble bath.