Johnson, William             William Johnson

TitleWater can be fun but too much                                                                                                                          can cause plants to suffer and even die.

Too much rain stresses plants

RAIN, RAIN, go away – or at least don’t stick around the entire day. News flash: Be careful of what you wish for as it may come true.
It seems that, while rainfall generally has not lasted for a whole day on most recent occurrences, we have been receiving an overabundance of showers.
Yes, it has been a really wet spring but I figure I would rather have a spring that’s a bit overly wet than one that’s a bit overly dry. The memory of 2011, with its record-breaking 100-plus-degree temperatures and drought conditions is still too vivid for me to complain about.
I attended a cookout over the past weekend and I was asked by several folks if the overabundance of rain will harm plants in landscapes and gardens.
Heavy rains, particularly when they persist over an extended period, place stresses on plants in our landscapes. Plants native to drier climates are particularly vulnerable to this type of weather.
As plants need water, what’s the issue with too much rain?
Although soil may seem rather solid, there are lots of spaces between the particles. Depending on soil type – clay versus sandy – and organic matter level, the amount of open or air space in a soil will range from 25 to 50 per cent.
These spaces hold air and water and the roots of plants need both. Roots absorb oxygen from the air spaces in the soil.
When it rains or you water a plant growing in a container, the air spaces in the soil begin to fill with water and the air is displaced. Gravity pulls on the water and it moves downward. As it does, air moves back into the soil spaces.
If rain occurs frequently over an extended period, the air spaces in the soil are kept filled with water. This deprives the roots of the oxygen they need.
If these conditions continue long enough, the roots stop functioning properly and may even begin to die. Although the soil is filled with water, the roots will not absorb it. This can cause plants to wilt, even though the soil is wet.
At this point, the roots are also more vulnerable to attack by fungal organisms in the soil that cause root rot and other diseases. Rot infections are highly damaging to the roots and are often fatal.
Our major defense against this is to make sure our landscape plants are well drained. Whether we are planting shrubs, bedding plants, perennials, vegetables or ground covers, the beds we prepare for them should be six inches or more higher than the surrounding soil. Our primary tool to achieve this is planting in raised beds.
Raised beds drain faster and dry out more quickly than ground-level beds. I hear gardeners complain during dry periods that raised beds may need to be watered more often – and this is often true. Still, we can irrigate and make sure plants have adequate water.
Adding organic matter to clay soils on an annual basis will facilitate soil drainage in clay soils.
By the way, if you have an in-ground irrigation system, turn it off. Turn it on manually to water plants if necessary. This recommendation may sound too much like common sense but I have seen so many landscapes being irrigated while it was raining that I feel it necessary to point this out.
So, what have we learned? We must not forget to consider drainage when designing beds and choosing plants. Drainage issues are best addressed during the installation of the beds. There’s not much we can do to improve drainage once the planting is done.
Raised beds are the best way to ensure good drainage. If you have a low area that tends to stay wet and you don’t want to put in a raised bed, you can certainly landscape the area with plants that tolerate wet soils. It is often better to choose plants adapted to the drainage in an area rather than try to change it radically.
Sometimes you might need to install a drainage system. The best time to evaluate the movement of water from your property is during heavy rain after it has been raining for a while.
Put on your rubber boots and grab an umbrella and head outside. You will be able to clearly see how the water is flowing across your property, where it is exiting and what might be done to improve its movement away from the property.
Given the frequency of showers lately, you should be afforded an opportunity to inspect rainwater flow in the very near future.

WMJ-13086 ~ Daylily flowers                                 Photo by William Johnson
Many flowers produced in the home landscape –                                                                                   including daylilies – are edible but some basic                                                                                    guidelines must be observed in selecting for                                                                                   consumption.

WHILE gardeners love flowers for the beauty they provide to the home landscape, few grow flowers for eating. That’s a shame because many flowers are edible in addition to bringing lively flavors, colors and textures to salads, soups, casseroles and other dishes.
Eating flowers is not as exotic as it sounds. Their use as food dates back to Roman times and to the Chinese, Middle Eastern and Indian cultures. Edible flowers were especially popular in the Victorian era.
So, just what are the guidelines for munching flowers?
Much of this information is pure common sense but it’s important to be mindful when venturing into new gastronomic pursuits. Many of us do not have a family connection of an experienced “elder” to tell us which flowers might be safely edible, so it’s good to review some basics.
It’s important to be cautious. If you have allergy issues or a compromised immune system, it’s best to skip adventures with edible flowers unless you have total control over their production.
Identify the flower exactly and eat only edible flowers or the edible parts of those flowers. With tulips, for instance, only the petals can be eaten. If the taste of any flower is objectionable – too bitter, too sour, too spicy or just plain weird – don’t swallow it.
Flowers can vary in edibility depending on the time of year. Once you have established that a flower is safely edible, experiment with its flavor and texture at different times of the year.
Toxicity is a major concern. Some ornamental plants are distinctly poisonous though beautiful, including several adorning gardens at this time of year, such as bleeding hearts, lily-of-the valley and oleander.
Even though lovely daffodils may seem to be just the thing to top a birthday cake, stay away from using them. Other beauties to avoid eating include hydrangea and Texas mountain laurel.
Be sure the flowers you eat are free of pesticides. Regulations for how to use pesticides on food crops differ from regulations for ornamental crops. Be sure that the rose or pansy flower you have your eye on has not been treated with any pesticides whose use on a food crop is illegal.
Roses, for example, are sometimes treated with a systemic insecticide that is applied to the soil. This should not be regarded as safe for human consumption due to the use of a systemic insecticide that can remain present in most or all parts of a plant for several weeks after application.
When choosing flowers for edibility, look for those grown safely. Don’t pluck a flower at random from an unfamiliar location or make the assumption that flowers in florists’ displays are edible.
In most cases, the petals are the palatable part of the flowers listed as “edible”. Remove the stamens and pistils from larger flowers such as daylilies – the stamens are covered with pollen, which could aggravate allergies.
Reliably edible flowers include calendulas, dandelions, geraniums, nasturiums, pansies, roses, squash blossoms and sweet violets, but this is only a partial list of edible flowers.
One flower that is particularly abundant in many local landscapes is the daylily. While nowadays it is considered a delicacy by wild-food gatherers and knowledgeable chefs, it has a long history in China’s cuisine and medicine.
Daylily flowers can be used in a variety of ways. They add sweetness to soups and vegetable dishes.
Flowers that are half opened or fully opened may be dipped in a light batter of flour and water and fried in a wok. You can add the petals to egg dishes and salads.
Dried daylily petals, called “golden needles” by the Chinese, are ingredients in many Chinese recipes, including hot-and-sour soup.
Some food preparers have suggested that daylily varieties with pale yellow or orange flowers produce the sweetest, most delectable taste. However, it appears that taste is related to type of cultivar more than flower color, according to serious taste trials.
Eating flowers is not a weird or unusual gastronomic endeavor. If you like broccoli or cauliflower, or artichoke, then you are already a flower connoisseur since a head of broccoli or cauliflower is composed of a few hundred unopened flowers!
The general rule is that the flowers of most herbs and vegetables are safe to eat – with flowers of tomato, potato, eggplant and pepper being notable exceptions. Always check first because, as with anything in life, there will always be exceptions.
The guidelines provided here are definitely related to a common-sense approach to selecting other types of flower as food. Adding flower petals to a salad or garnishing a stack of pancakes with a small rose can be fun and effective but it’s necessary to inform yourself before ingesting your floral creations.

William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

Johnson, William             William Johnson

Milkweed assassin bugPhoto by William Johnson
The milkweed assassin bug is a commonly occurring                                                                             beneficial insect in local gardens and landscapes.                                                                                         Meet several more in a free public presentation being                                                                                     given by Post columnist William Johnson next Tuesday.                                                                                   For details, see At A Glance, below.

Johnson, William               William Johnson

THE EXTENSION fruit & pecan committee, master gardener volunteers and Galveston County AgriLife Extension office will co-sponsor a fruit orchard and garden tour on Saturday, May 16, from 9:00am to 12:00 noon. The program is open to the public and free-of-charge.
Three fruit orchards are on this year’s route and each will be open during the tour period. You will have the option of touring all three sites or any combination at your own pace and in any order you choose.
This year’s tour sites contain a wide variety of fruit trees, ranging from an impressive fruit tree orchard at Fruits ’N Such orchard at 6309 Avenue U & Bowerman Drive in Dickinson to the master gardener demonstration orchard in Carbide Park in La Marque. Peach, plum, citrus, fig, apple and other fruit trees can be seen also.
All three sites contain a wide variety of vegetables. They are grown in dozens of raised beds at Carbide Park, whereas they are grown in the ground at Fruits ’N Such.
Visitors may also tour an impressive herb garden next to the Fruits ’N Such orchard. If you’re looking for the freshest produce to purchase, you can pick it yourself at Fruits ’N Such.
If you are interested in seeing the amazing diversity of fruit trees that can be grown in a backyard, be sure to include a tour of master gardener Bill Verm’s home orchard in Santa Fe.
If you have an interest in roses, be sure to visit the display beds of earth-kind roses at the Carbide Park site. Homeowners love their magnificent blooms and fragrance.
Roses have had a centuries-long reputation of being the most neurotic members of the plant world. Consequently, gardeners spend considerable cash buying fertilizers, pesticides and fungicides to sustain their roses, and much time pruning, deadheading and watering them to keep them blooming. Roses that qualify for the earth-kind designation are very low-maintenance and perform very well under a variety of growing conditions.
To obtain a map with directions to the tour sites, visit Galveston County AgriLife Extension office in Carbide Park, at 4102-B Main Street in La Marque, or call 281-534-3413, ext 1-1.
A printable copy of the tour map and additional details are available on my website, the address for which is provided with this column (click on the “Extension Educational Programs” link).
Area homeowners who grow – or plan to grow – fruit or vegetables for home use will find the tour sites to be of considerable benefit.

At a glance

WE OFTEN find bugs annoying but there are lots of insects and other critters that help keep gardens and plants healthy. Local gardeners are likely to name lady bugs or honey bees when asked to give an example of a beneficial insect commonly found in Gulf Coast gardens and landscapes.
Local gardeners would be surprised at the diversity of beneficial insects already residing – and working – in their backyards.
To learn more about beneficial insects and how to identify them, preregister for an upcoming educational program entitled Beneficials In The Garden And Landscape. The illustrated presentation will be provided by William Johnson at 6:30pm on Tuesday, May 19, at the Galveston County AgriLife Extension office in Carbide Park, 4102-B Main Street, La Marque. Preregister by e-mail to or by phone at 281-534-3413, ext 1-2.

William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

Johnson, William           William Johnson

??????????                                Photo by William Johnson

Each of us can do something to help insects                                                                                           pollinate our garden plants, including honey bees.                                                                                    Simple actions, ranging from planting more                                                                                         pollinator-attractive flowers to using pesticides                                                                                             only when necessary and according to their label                                                                                 directions, can make a big impact.

A busy and challenging month

BUSY DAYS are in store for the May gardener in completing spring chores and preparing for summer, so here’s a guide that might be helpful for planning this month’s gardening activities.
A Home Fruit Growers’ Tour will be conducted on Saturday, May 16. Three fruit orchards are on this year’s tour, each of which will be open from 9:00am to noon.
This year’s sites contain a wide variety of fruit trees ranging from a peach orchard – Fruit ’N Such orchard at 6309 Avenue U, Texas City – to the master gardener demonstration orchard in Carbide Park in La Marque and a sizeable home orchard in Santa Fe.
Tour maps and additional details may be downloaded from my website address, which is shown at the end of this column – click on the “extension educational programs” link. Additional information will also be provided in next week’s garden column.

Sensitive vegetables
The unusually wet and cool spring has delayed planting of many vegetables. Even tomatoes have had an unusually tough time this spring.
Normally, I recommend that okra be planted during April but this year it would have been better to have waited until May given the occurrences of cool temperatures over the past few weeks.
This cousin of cotton especially needs to be planted in a warm soil. Proven varieties include Emerald, Clemson Spineless and Jade. After planting, plan to thin plants to 24 inches apart in the row, with rows 36 to 42 inches apart.

Squash set
Don’t be concerned if the first several squash fruit fall off the plant before they reach an edible stage. The first flowers to form in squash in early spring are the females – those with the miniature fruit right under their yellow flowers.
With no male flowers being present, no pollination takes place. However, within a few days the male flowers will be formed and normal fruit set should take place.
Interestingly enough, it’s the reverse in summer plantings – the male flowers tend to develop first so no fruit set occurs until the female flowers develop.

New plants’ care
Spring- and winter-planted trees and shrubs will be establishing their root system this month and thus are very susceptible to transplant shock during the summer if not provided proper care during extended periods of dry weather.
The first summer of growth is a critical period for all newly planted trees and shrubs. To reduce transplant shock, be sure to water them thoroughly and deeply as needed during dry weather rather than giving more frequent, light sprinklings.
Plants should also be mulched with shredded pine bark or pine needles. A four-to-six-inch layer of mulch will also help control weeds, maintain more uniform soil moisture and keep the soil cooler. As a result, the degree of transplant shock will be significantly minimized.
Also, add to the list of benefits the fact that mulched trees and shrubs will grow much better than non-mulched transplants.

Summer annuals
For instant color, purchase already-started annual plants. Select short, compact plants. Remove faded blooms for more productive flowering.
If beds are not mulched, then lightly cultivate the upper soil so as not to disturb shallow roots. Doing so improves water absorption, reduces soil compaction and aids in weed control.
Plant annuals that take the heat such as periwinkle, purslane, portulaca and lantana.
Annuals for shade include impatiens, coleus, caladiums (the tubers are just about out of stock but potted plants are still available) and bedding begonias.
Caladiums will often produce a single flower stalk right after the first leaves are produced. Early removal of the flower stalk will encourage them to produce more lush leaf growth.

Pollinator protection
We are busy in the garden this month and so are honey bees and other insect pollinators. Let’s do all we can to protect these valuable little insects.
Many insecticides are highly toxic to bees. Some cannot be safely applied at any time that target plants are in bloom, while others should be applied during late evening, when bees are less likely to be foraging for nectar and pollen.

William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at

Johnson, William

THE SPRING ritual of phone calls and visits to the AgriLife Extension Office in addition to urgent e-mails submitted by county residents this time of year is proof that insect pests and disease problems on landscape plants can be expected to return with warmer weather conditions.
The following is a sampling of questions asked by local residents:
Q: My oak trees have been invaded by an army of caterpillars that are very hairy and quite colorful. Any ideas on the name of this caterpillar? Is this a stinging caterpillar? Should I treat my oak trees?
A: This year is shaping up to be an active year for caterpillars across Texas. Populations of tent caterpillars have been enormous in some areas of Texas. Tent caterpillars have caused dozens of blackouts in the Dayton, Texas, area when caterpillars moved from tree limbs onto high voltage transformers and caused electrical shorts. Galveston County residents are fortunate in that tent caterpillars rarely occur in this area.
The caterpillar that has alarmed local residents is commonly known as the Live Oak Tussock Caterpillar (scientific name is Orgyia detrita). The Live Oak Tussock Caterpillar does not form tents. While this caterpillar is known to occur in low numbers in most springs, residents in the League City and Friendswood area are reporting major outbreaks of this insect pest.
The good news is that a healthy tree or shrub can generally tolerate a total defoliation without suffering permanent damage. By the time homeowners notice the leaf damage on their oak trees, most caterpillars have stopped feeding and are entering the non-feeding pupal stage.
A mature caterpillar is about 1.25 to 1.5 inches long, with two long tufts of black hairs projecting forward from the head and a similar tuft of black hairs projecting backward from the rear of the body. Four dense patches of hair occur midway on the topside of the caterpillar’s body.
While Live Oak Tussock Caterpillars are not regarded as being stinging caterpillars, it is advised that people do not handle them. Some people aren’t bothered by the caterpillar but others could have a reaction that ranges from a mild to fairly severe rash. Parents are advised to keep an eye on their toddlers when outdoors to ensure that they do not make contact with the caterpillars.
I suspect that the abundance of Live Oak Tussock Caterpillars is correlated with the mild temperatures over last winter.
Q: The leaves on my oak trees have developed numerous bulges or bubble-like structures that eventually turn black. Some trees have lost most of their leaves. What causes this?
A: Our office has received numerous visits, e-mails and phone calls reporting similar symptoms on leaves of oak trees across the county. Your oak trees have a disease known as Oak Leaf Blister which is caused by a fungal pathogen.
Oak Leaf Blister causes small, rough (concave-convex) spots as leaves expand in spring. The spots turn pale green and become somewhat thick, then turn brown or greenish brown and eventually becoming black. Leaves with numerous spots will fall prematurely.
Control of this disease requires an application of a fungicide during early spring before new growth starts. It should be noted that once diseased foliage is present, fungicides will not “fix” the damage that has been done. Diseased leaves will simply fall naturally. Thankfully, it looks worse than it actually is. Since the tree’s health is not in danger, don’t be alarmed by this pesky fungus.
Once the blisters appear, the application of fungicide will be a wasted effort.  Fungicide applications (with products containing chorothalonil or mancozeb as active ingredients) used to prevent this disease would have to be applied in late winter before the tree buds begin to grow.   If Oak Leaf Blister is serious enough to cause leaves to fall, rake them up and dispose in curbside trash pick up.  Otherwise, go fishing!
I am not surprised by the widespread occurrence of Oak Leaf Blister this spring as this disease is favored by high rainfall during late winter and early spring when leaves are emerging.  In contrast, not a single case of Oak Leaf Blister was reported during the spring of 2011, which was a record drought year.

Photo by William Johnson
This year is shaping up to be an active year for caterpillars across Texas. While the Live Oak Tussock Caterpillar is known to occur in low numbers in most springs, residents in the League City and Friendswood area are reporting major outbreaks of this insect pest.

William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at