What is slime mold?
David, a viewer, found slime mold in mulched pathways and garden beds, and he wants to know if it’s harmful, and what to do about it. Well, with all the rain we’ve had this spring, and with temperatures so warm, this substance has been showing up in many gardens. In fact, my friend Mike, who works for the Austin Fire Department, recently told me that he responded to a call from a school to check on a possible “hazardous material” found on the children’s playground. What did it turn out to be? Slime mold. Slime molds are unique creatures that don’t fit into any categories that we’re familiar with. Although they have fungus-like characteristics, they aren’t fungi. They exist in nature as a “blob;” that is often bright yellow, and even sometimes red. Their preferred food source? Bacteria. They occur when there is high relative humidity and relatively warm temperatures: exactly the conditions that we had this spring. So on to David’s actual question. Are slime molds harmful and what to do about them? Although they are unsightly, dare I say, “gross,” they are not harmful to humans or animals. And they’ll run their course fairly quickly, so there’s no need to do anything about them, unless you can’t stand to look at them, in which case, simply remove and toss them in the garbage or compost pile, or just break them up with a rake or a strong jet of water. If slime mold returns, even when we aren’t getting rain, it would be because the area is being over-irrigated.
Sterilizing plant pots: Do we need to clean plastic six packs or pots and clay pots to reuse them for cuttings or to plant new container plants? How should we do it and do we need to sterilize them against disease?
The answer is a resounding yes. All pots should be cleaned and gently scrubbed before re-use. Although the likelihood of contamination is low, it’s always better to err on the side of caution. At the very least use a warm, slightly soapy liquid and a scrub brush to remove all remaining debris from the container. You should also, whenever possible, use a weak bleach solution to disinfect any possible microbes, especially in square containers, like those six-packs, where it’s almost impossible to get all the potting soil out of the corners. To make a 10% bleach solution, simply mix one part bleach to nine parts water. Be sure to rinse those bleached containers, and allow them to thoroughly dry before reusing them. And just a reminder about repotting plants. In containers, plants prefer to be crowded, so don’t use too large a container. A good rule of thumb is to move up only one container size, for example from a 4” pot to a 6” one, when transplanting container plants. And if you’re creating a container with multiple different plants, maybe for a splash of annual color near your porch or patio, be sure to fill the container entirely, with each plant almost on top of the other one, so that you can barely, if at all, see the soil.
Does it really take a century plant a hundred years to bloom?
Viewer Diane says that their home was vacant over a year and a half before they purchased it, so the yard is really out of shape. Well Diane, the best place to start would be your soil. If the landscape has not been irrigated since the house was vacated so long ago, the soil is going to be very compacted. So you should plan to rent the proper equipment, or hire someone to aerate. Then, put the landscape back on a regular irrigation schedule. Even watering just once a month, if we aren’t getting any rain, will go a long ways toward keeping your soil from drying out completely and shrinking in on itself. Compacted soil is like rock to a plant’s roots, so growth is really inhibited. But aeration will create nice little holes where irrigation water and oxygen can move into the soil more easily, helping to soften it up. As for the weeds, keep pulling them, as you say you’ve already started, and use mulch around any established trees and shrubs, or any plants that you intend to keep. Diane wanted to know about putting down newspaper under the mulch, and yes, that’s a great idea. Mulching alone does help to inhibit weed growth, but really only works if the weed seeds haven’t yet germinated. Once the seedling emerges, the plant usually has plenty of stored carbohydrates to push up through your mulch, reach the sun, and grow by leaps and bounds overnight. A layer of newspaper, one section or 6 to 10 pages will usually do the trick. The newspaper barrier is a little harder for weeds to push through, although not impossible. Be sure to moisten the newspaper before you put the mulch on top of it. If we get lucky and get a hard rain soon, your mulch will wash right off of the dry newspaper in a little avalanche.
Wilting tomatoes: What to do with tomatoes when hot weather comes early or sporadically?
This simple question has a very simple answer: no. Okay, a little more detail: Century plants DO take a very long time to bloom, but it’s far less than a century. It’s more like a decade or two, and usually somewhere between 10 and 30 years. Unlike most plants, which you probably want to bloom immediately, and year after year, this is one that you want to wait as long as possible to bloom, since once it does, the main plant will die. And while there are few things more beautiful than a century plant in bloom, there are few things uglier than a dead one. As soon as the century plants and other Agaves around town start blooming, I get inundated with calls from frantic people who know enough about Agaves to panic at the first sight of its delicate little floral bud. Everyone wants to know if they can stop this process and keep the parent plant alive. And unfortunately, the answer is no. This is one area of nature that man has yet to figure out how to tame, so you should just enjoy that beautiful bloom stalk. And it will be striking, getting up to 30 feet tall. These bloom stalks can actually be hazardous, since as they grow and mature, the mother plant is slowly dying, giving that lanky bloom stalk less stability with each passing day. Eventually, if you don’t remove the plant first, the top-heavy bloom stalk will topple over and rip the dead Agave out of the ground, which could make for quite a mess, and even some damage to surrounding structures, if you aren’t careful. Some people even stake the bloom stalk to balance its weight. If you’d like, you can collect the seeds from your Agave and replant. But even before flowering, you should have noticed some little baby plants around the mother plant. These plantlets are basically little clones, and can be dug up and planted in other areas of your landscape, or placed in containers, so that you’ll have a replacement for that spot when the original plant dies.
Winecup, Callirhoe involucrate
Winecups are perennial and are listed to be slightly deer resistant, which basically means that the deer will probably choose to eat all the other plants in your garden before they eat this one. Winecups form a beautiful, sprawling mat across the surface of the ground, and are covered in flowers from very early spring until the heat of summer arrives. They need very little water and require very well-drained soil, performing best in shallow, gravelly areas, and even preferring the small cracks between landscape pavers to a richly amended garden bed. So be careful using organic mulches around this plant or it might rot. Winecup gets only about 6 to 12” tall, including the flower stalk, but can spread up to 5’ wide. In late summer, you should trim back any dead growth that occurred due to the heat, which will encourage a flush of growth in the fall. Winecup should also be pruned back to its base in late winter, before the new spring growth emerges. Another great thing about winecup is that it grows very easily from seed, so that you can establish plenty of them in your garden, without a lot of expense. As with our other wildflowers, winecup seeds should be sown in the fall, while transplants should be planted in the spring. And be sure to plant your winecups in full sun.
Cenizo, Leucophyllum frutescens
Texas sage is also known as Texas sage, purple sage, Texas ranger, and many other common names. Cenizo is extremely drought tough and needs very little water once established. In fact, this shrub does not like “wet feet,” so be very careful if planting in clay soils. There are a multitude of different varieties of cenizo to choose from, differing not only in leaf and flower color, but also in height and width. So when choosing this plant, be careful to get a variety that has the characteristics that you want, especially when it comes to size. Cenizo does not respond well to heavy pruning, so if it outgrows its space in your landscape, you won’t be able to prune it back and keep it smaller. Overly-pruned cenizos will show lots of die-back, especially in the center of the plant, with only a little growth at the tips. Unfortunately, this shrub is often planted in rows and sheared back to make a hedge. This is not a good practice, and will cause the shrubs to look very ugly, twiggy, and almost dead. Which they will be, since most of the living tissue will have been removed. The most common cenizos have gray-green leaves with light lavender flowers. But you may also found varieties with a greener leaf and deeper lavender blooms. More rarely, you may even find some with white blooms. Some will also have more and larger flowers than others, giving you a wide palette to choose from. I have seen Texas sages abandoned by the side of the freeway in El Paso, happily blooming their heads off in the full heat of summer, after the rainy season has arrived. These west Texas natives are also known as barometer bush, because they bloom in response to heat and relative humidity, leading some to say that they are good predictors of rain. Cenizos require full sun to bloom and be healthy, and really don’t tolerate shady areas.
There are many great species to choose from, especially as more people begin to look for low-water requiring plants in our continued drought. Like the century plant, most Agaves take quite a while to bloom. They are also all monocarpic, meaning that they die after blooming. But even so, they are well worth the effort, especially in a low-water landscape. Most Agaves have stiff, spiny-tipped leaves that should be avoided, but some, like squid Agave, have soft, droopy leaves which aren’t so lethal. They should all be planted in very well-drained soil, so if you have heavy clay and can’t change it, you should choose other low-water plants. If you can amend the planting area, replace the clay with very sandy soil, mixed with coarser decomposed granite, and consider building bermed areas, so that drainage is increased even more with the elevation. Also, be sure to know the origin of your Agave choice. Some Agaves are native to Central Texas and can take our occasional cold winters just fine. Agaves that are native to the Chihuahuan desert would also be good for our area, since their native region has cold winters. But Agaves native to the Sonoran desert of southern Arizona are not accustomed to the cold, and should be protected in winter. You should also take care with the ultimate size of your chosen Agave. The century plant is one of the larger ones, getting up to 6’ tall, without the bloom stalk, and 10’ wide. But another great Agave, Queen Victoria, stays quite small, less than 2’ tall and wide.
Native prairie verbena, Glandularia bipinnatifida
Another of our beautiful native wildflowers may be seen along roadsides and in fields, if not overshadowed. This flower has light purple, round clusters of flowers on short stalks. Like most of our native wildflowers, prairie verbena does well in shallow, rocky, disturbed soils. It can grow in full sun but can also tolerate shade. Spreads easily, making it a great groundcover choice, or to fill in near rocky paths and borders. It has blue-green, velvety-looking foliage, with highly divided leaves and will do fine on natural rainfall, but will perform a little better if irrigated but don’t overwater. The plant stays around 6” tall and spreads easily to 18” wide, and much wider. Is a perennial, dying back to the ground and returning from the roots each year. Looks great planted in large, open areas and left un-mowed although easy to miss when planted with other, taller wildflowers. Listed as hardy to -28 degrees, so these would not have any trouble re-emerging after a cold winter.