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Master Gardeners answer lots of questions. Here are a few of the ones we receive most frequently. 

Have a question not addressed in this list?    Ask A Master Gardener

Master Gardeners are volunteers who work through their cooperative Extension office to provide horticultural-related information to their communities. In exchange for volunteer work, they receive extensive training in a variety of horticultural topics.

To become a certified Master Gardener, candidates must complete both the training classes and meet specific volunteer requirements.

In Texas, training is provided by the local Texas AgriLife Extension Office. The training schedule and volunteer requirements are different from county to county. Therefore, you'll need to contact your county to get a training schedule and requirements for certification. The Collin County program offers a minimum of 65 hours of instruction with topics including Earth-Kind® garden management, Integrated Pest Management, soil management and water conservation, lawn care, ornamental trees and shrubs, plant nutrition, vegetable and fruit gardening, native perennial and annual flowers and much more.

Please visit our Master Gardener Training Page for details. 

Rose Rosette Disease has spread through North Texas, negatively impacting our ability to grow healthy roses. Effective, community-wide control strategies will be necessary to eradicate this viral disease.

Once an infected rose is properly diagnosed with this disease, the entire plant, including the roots, should be removed and disposed of according to local municipality yard waste disposal guidelines.

Rose Rosette symptoms include:

  • "Witches’ broom"
  • Malformed flowers and leaves
  • Excessive leaf growth and thorniness
  • Extreme red discoloration of plant tissue
  • Lateral shoot elongation (abnormal lengthening of side branches/twigs)
  • Enlarged/thickened stems

To view photos and learn more, visit this online resource from Texas A&M Agrilife Extension.

This sticky sap is a result of aphid activity on the Crape Myrtle tree. Spraying with water will help to dislodge the aphids from the tree. You may also want to spray with insecticide soap to remove aphids underneath the leaves.

If you examine leaves of the Crape Myrtle closely, you should notice small bugs similar to those in this photo:

Underside of leaf with small insects

Small insects on underside of Crape Myrtle leafFor more information, please refer to this article from Agrilife Extension about Aphids in Texas Landscapes.

Oak Leaf Blister is a fungal disease that is relatively common during spring seasons that follow a wet winter, coupled with early warming temperatures.  The good news is, Oak Leaf Blister does not seriously affect the overall health of the tree. This article from the TAMU Extension provides more information on Oak Leaf Blister.

Blistered looking oak leaves

If you are worried your Oak tree may have a different problem, this additional article from TAMU Extension details other common Oak tree diseases.

You can also consult a Certified Arborist who can give you a definite diagnosis.  To locate a Certified Arborist in your area, consult the International Society of Arborists website here.

St. Augustine grass is susceptible to many problems that may cause patches of it to turn brown, including:

  • Take All Root Rot (TARR) - symptoms appear in April and May
  • Chinch Bugs - symptoms appear June through the summer
  • Gray Leaf Spot - symptoms appear June through early fall
  • White Grub Worms - symptoms normally appear in October
  • Brown Patch - symptoms appear as a result of unusually wet weather or over-irrigation

To learn how to diagnose each of these problems and about how to treat them, check out this article on St. Augustine Grass Care.

St. Augustine Grass Care


The best way to eliminate fire ants in your lawn and landscape is to use the Texas Two Step Method.

  1. The first step is to use baits. These are slow acting and can require weeks or months to work but contain extremely low toxins. They are 80 to 90 percent effective. The worker ants take the bait into the hive to share with the queen, either killing or rendering her infertile. Put baits out when ants are actively foraging. Fall is an excellent time to bait as the ants will feed during the winter while you are indoors. Follow package directions carefully for best results.
  2. The second step is individual mound treatment. These are fast acting to eliminate existing mounds. There are commercially available dust, granular and drench products on the market. Closely follow instructions on the label. You can also pour 2 to 3 gallons of boiling water on the mounds. This will be about 60% effective. The hot water will kill any grass or plants that are touched by it.

Good news: even with heavy clay soil and automatic sprinklers, this can be done.

In order to determine how much water your sprinklers are getting out, you can perform a Catch-Can Test. Place small, shallow empty cans (such as tuna) around your area to be tested. Turn the sprinklers on. When your sprinklers have filled the cans to a 1" depth, you will know how long your system takes to get the correct amount of water out. Every sprinkler system is different, so this is the only way to find your particular output.

However, with heavy clay soils, there could still be runoff. The best way to correct this is to run your system in small increments for each station. You may need to do this two or three times. By waiting between cycles, the water has a chance to soak in. This process is called The Cycle-and-Soak Method.

  • For example, if you have 6 stations in your landscape, you could set them to each run for 5 minutes.
  • By the time the last station has run, the turf around the first station has had time to soak up the water.
  • You would then start the process over again.
  • Depending on your particular landscape, each station could run for 5 to 10 minutes.

If you have already determined how long it takes for a 1" depth, you will know how long to run each station and how many times to cycle them.

Organic mulches are the best to use in your landscape. Native hardwood mulches are readily available from local municipal recycling programs and also many retailers.

These hardwood mulches will break down over time to act as a natural fertilizer to your plants. Mulches also discourage weeds, cool the soil temperature, protect from erosion and conserve water in the soil.

Mulch should be kept at a 3-inch depth and can be applied any time of the year, although the most common time is in the spring. The depth of the mulch should be checked in the fall as well.

The optimum time for pruning of trees and shrubs is January through early March when trees and shrubs are dormant. This is also the best time to move established plants to new locations.

When considering the pruning of evergreen shrubs such as photinias, hollies or pittosporum, keep in mind the new growth that will cover your newly pruned areas will not occur until March or April. This means, the earlier you prune, the longer you will have to look at the (potentially) ugly scene you have created. Be patient and wait until January or February to prune; your plants will appreciate the consideration.

Also a word to the wise: THINK and PLAN before you PLANT! First consider the intended location, and then choose the best-adapted shrub or tree for that area. For example, if you have a small space, stay away from plants that grow to be massive. All plants seem small at the nursery, so a little bit of advance research will pay off in the long run. In short, if you plan ahead, VERY LITTLE PRUNING WILL EVER BE NECESSARY.

A list of recommended trees and shrubs with their ultimate size is available from the County Extension Service Office. 

While fall may be the ideal time to plant spring-blooming bulbs, sometimes things happen…time gets away from us, life events occur that take precedence, weather changes too quickly…now what? It may not be too late. If you are reading this and already have the bulbs and want to plant them, you have nothing to lose, right? However, if you don’t have bulbs please do not run out and buy them now.

Let’s be realistic, you may be taking a chance…agreed? Planting bulbs late may or may not be successful.

When the bulbs bloom (early, mid, or late season) may be a factor.

  • The bulbs may not perform as well as if they were planted at the ideal time. (Perhaps you will get leaves and not flowers this year…they may perform better the next year.)
  • They may not come up at all, depending on the type of bulbs you have or if freezing weather interferes with root formation. Or…
  • They may come up and be just beautiful!

First, check each bulb to see if they are healthy. The bulbs should be firm and earthy smelling. If they are soft, mushy, disintegrate or have a bad odor, discard them.

Depending on the variety of bulbs you have there are several options. If they are naturalizing bulbs for our area (North Texas), try planting them…

In the ground (sunny location, good drainage)…depth 2-3 times the height of the bulb; spacing 2 times the width of the bulbs. Add 3 inches of mulch.

In pots, similar to above. You may plant them closer together (no touching), since ideally they will be planted in the ground after they bloom and the leaves have turned brown.

  • Do not remove the leaves prematurely. (You can bring in the pots if temperatures drop below freezing.)
  • Avoid the temptation to over fertilize. This attempt to give them ‘love’ may actually be harmful to the bulbs.
  • Hopefully, you will be able to enjoy the flowers of your dreams. If however, the bulbs leaf out, but the flower does not bloom or perform up to expectation, don’t panic. Give it another year. The leaves are nourishing the bulb for next year’s flower display (photosynthesis…it’s what they do).

Another option is an indoor container…

  • Select a glass container. Consider the height of the flower and be sure the container is deep enough, so that the leaves and flower to not fall out or over turn the container.
  • Add clean river rocks or stones (2-3 inches) to the bottom of the container.
  • Add about ½ teaspoon of horticultural charcoal to the container to keep the water fresh.
  • Arrange the bulbs close together (not touching) on top of the stones.
  • Add water to just below the base of the bulb. Do not allow the bulb to sit in water.
  • Place the container in a bright light and watch. Hopefully, you will be rewarded with blooms.
  • Be sure to let the leaves die naturally (do not cut them off prematurely). Immediately plant in the garden as you would transplants…in spring. Remember, if they naturalize, they would spend the remainder of the year in the ground anyway. Do not wait too long or let them deteriorate.

This ‘late-planting’ approach is not research-based or recommended. However, it is what you can do to give unplanted bulbs a chance. Give it a try…you may be rewarded!

Common Gardening Mistakes

Many beginner gardeners say things like, "I have a brown thumb. I can't grow any plants."

Don't worry... even Master Gardeners make mistakes and lose plants here and there, but we learn by doing!

The good news is, we have created a list of very common gardening mistakes that may save you a lot of effort and time.

Garden smarter, not harder!

North Texas is very unique. Our weather and soil conditions make it tougher to grow some plants, even if they may grow well in other parts of the country. Make sure you purchase plants that will grow and flourish in our North Texas climate and Houston Clay soil.  Native or well-adapted plants naturally thrive here, and there are so many beautiful and hardy species to choose from.

Check out the excellent Texas Smartscape plant database to browse through the best plant choices for our area!  

Different plant species require different amounts of sunlight and moisture.  If you place a plant in a location where these needs are not met, your plant may not survive.

Pay attention to sunlight recommendations for plants. If the information tag recommends shade, don't plant it in full sun. Likewise, plants that require full sun will suffer in the shade. Many full sun plants do well out in the open all day. Keep in mind, however, that "full sun" in another part of the country is not the same as full sun in North Texas! Due to our intense summer sun and heat, we sometimes need to dial back sunlight recommendations, especially if a plant was was shipped from a nursery in another part of the country. 

The same goes for moisture recommendations. Pay attention to your information tag and make sure you're giving your plant the amount of water it needs. Some plants prefer to have "wet feet," while others require an area with well-drained soil. Similarly, don't place moisture-loving plants in an area that stays dry most of the time, or place a dry-loving plant in an area that gets watered heavily. Many native/well-adapted plants for North Texas are relatively drought-tolerant, and therefore may require less watering once established. 

Pay attention to wind exposure and micro-climates. For example, planting near a wall can shield a plant from the wind, but keep in mind that materials like brick also absorb a lot of heat during the day. Make sure any plants you place near a brick wall are heat-tolerant.

For more information on choosing the right plant for the right location, check out this article on The Best Plants and Trees to Grow in Texas Landscapes.

It may seem surprising, but over-watering kills many more landscape plants in North Texas than drought.

The proper way to water is infrequently, but deeply using The "Cycle-and-Soak Method." Unfortunately, if too much water is applied at once, it will simply run off of our North Texas clay soils and into the street. In contrast, the Cycle-and-Soak method allows water to sink deeper into the soil, which promotes deeper and healthier root growth.

  • The first step is to perform the "Catch-Can Test" on your own automated sprinkler system.
  • To do this, just place a few shallow cans (like tuna cans) throughout your yard and run your system to determine how long it takes to fill all of those cans with 1" of water.
  • If you discover it takes 20 minutes per station/zone to provide that 1", you can then split the run-time into segments. For example, you can run the system for two successive cycles of 10 minutes each, preferably in the early morning hours, once a week, with time in between the cycles for the water to soak into the soil.

For more information on proper watering techniques, see the following articles from Texas A&M Agrilife Extension:

With synthetic fertilizers, less is more.

Carefully follow application instructions provided on fertilizer containers. It's the law! Better yet, compost your grass clippings, leaves and yard trimmings, and use your compost as a natural fertilizer.

  • Overuse of synthetic fertilizers is especially dangerous because it can actually "burn" your plants.
  • It can also result in unnatural growth spurts which in turn attract more pests and diseases.
  • More importantly, however, watering excessively-fertilized plants and lawns results in harmful "non-point source pollution." This synthetic fertilizer runoff sends unnatural amounts of nitrogen and phosphorus into local creeks and streams. The presence of these extra nutrients creates a phenomenon called an "algae bloom," that can destroy an entire ecosystem. Basically, the excessive nutrients cause an enormous amount of algae to grow over the top of the water, eventually blocking out sunlight other organisms need.  When the algae eventually starts to die, its decomposition uses up the available oxygen. Without enough oxygen in the water to breathe, mass fish kills are often a result.

For more information check out this article from Texas A&M:

Think before you spray: "is there a better way?"

Many gardeners see insects on their plants and immediately reach for the spray. In truth, chemical pesticides are actually the last solution that should be tried. Gardeners should instead ask themselves a few questions:

What kind of insect is it? Is it harmful to the plant or not?

If the insect is considered a pest, does it warrant spraying?

    • Is there an infestation on the plant or just one isolated bug?
    • Is it actually doing damage or just hanging out?

Are there birds, beneficial insects or spiders in the immediate vicinity that might either a) take care of the pest problem themselves or b) be harmed as a result of spraying a pesticide? Learn to live with a few bugs. If it weren't for them, many birds, spiders and beneficial insects wouldn't have anything to eat.

If a pest infestation is present, is there an underlying reason why?

    • Check soil, moisture and light conditions. Pests will usually attack an already weak plant.

If you do decide to apply a pesticide, always start with the least toxic variety, and apply it in the early evening after honeybees have left the area. Always follow label instructions (it's the law). The same advice applies to fungicides and herbicides as well.

For more information see:

Just like the plants and the weather, the soil here in Collin County is tough!

In most areas of the county, our soil is a dark, sticky clay that is often referred to as "Black Gumbo". It is known for being difficult to dig in, and can also be somewhat hard for plants to grow in. While the nutrient levels are generally acceptable, oxygen levels are low due to clay soil's high density. In addition, water tends to run off rather than absorb when clay soil is dry. Lastly, our clay soils lean toward the alkaline side (meaning a pH value higher than 7/neutral). This can be a problem if you're trying to grow plants that prefer more acidic soil.

Before planting, gardeners should amend the soil with copious amounts of organic matter. Compost and finely chopped leaves are excellent additives. A somewhat new product called "expanded shale" has also proven helpful in loosening clay soils when mixed with compost. Despite what some folks may recommend, do not add sand in an effort to amend clay soil.

Tip: working in clay soil while it is wet is not recommended. Not only does it create a huge mess, but it also depletes the oxygen levels even more. 

For additional recommendations on preparing your soil for planting, check out this article from Texas A&M:

When in doubt, leave more space in between plants rather than less.

We've all seen those glossy magazine photos of gardens with tons of pretty plants all crowded together. Not planning enough space for plants to grow, however, can cause all kinds of problems for your landscape in the long term. For example, moisture and nutrient levels of individual plants will be depleted, and air circulation around plants may become insufficient. Plants and seeds usually come with spacing instructions, so try to follow them. 

When you are planning out your landscape, keep each plant's mature size in mind.  Make sure to leave enough empty area around each plant, so it can grow without crowding others in the vicinity. 

For more tips on how to plan before you plant, check out this article from Texas A&M:

There is such a thing as "planting too deep."

Most plants benefit from being positioned so the crown is slightly above the soil surface. This also allows for eventual soil settling.

Trees should be planted so that the root flare is generously exposed - avoid the 'telephone pole' look!

For more information on trees:

Cutting off too much of any plant can result in death, however with some plants, not pruning at all can limit blooming.

In addition, timing is critical. Trimming at the wrong time can expose some plants to pests and diseases.

So, what's the happy medium? Read on:

Plan ahead! Although a plant may bloom in the spring or summer, it often needs to be planted several months prior.

Wildflower seeds, including bluebonnets, should be planted in late fall.

Spring-flowering bulbs should be planted around Thanksgiving in our area. 

Perennials benefit from fall planting, thus giving them a chance to establish roots before winter.

Most trees and shrubs will do best if they're planted during the fall or winter.

If you're a vegetable gardener, learn which veggies are considered "cool weather" crops and stick to planting them at the proper time.


Need some helpful monthly reminders (don't we all)?  Check out the Monthly Gardener's Checklist for some
timely to-do tips!

Monthly Garden Checklists

Many people do not realize that planting an invasive species can damage both the environment and the economy.

An "invasive species" is defined as "a species that is non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health." (Executive Order 13112). 

Did you know that the popular Pincushion Flower (Scabiosa atropurpurea L.) is considered an invasive species here in Collin County? Other species on the list may surprise you.

  • Check out for more information about local invasive plants, so you can plant responsibly!

If you have curious children or pets, avoid planting anything poisonous that could potentially be interacted with, touched or ingested. 

The following resources may serve as helpful guides, but please always research whether plants are poisonous before installing them (especially if you will have little hands and/or paws visiting your garden).

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