I’ve been reminding people for more than two decades that all gardening success in Texas starts with the soil.
Sadly, we often have to make those soils happen because they don’t always occur naturally.
This message really needs to sink in with folks who have moved to this region from northern states. Up there, while you can’t garden for about half the year, you are often able to just throw things into existing soil and everything works.
We can’t do that here because of the clay soil that abounds in the region. Some call it clay, others call it caliche, and some call it gumbo. Whatever you call it, it simply can’t sustain much plant life without being amended with organic matter.
I remember feeling so clever when I wrote my first book about gardening and titled the soils section “Planting in Southeast Texas Gumbo – Not a Cookbook Chapter.” I later learned that people passed over it or didn’t thoroughly read it because it came across to some as a joke.
Today, though, you need to take this article very seriously. Longtime fans who have all my books will notice this is a compilation of everything I’ve written about soils and mulches over the past 15 years.
In building beds for this region, rose soil is still the best starting point. Before I became a garden guy on Houston radio, my predecessors and my agricultural mentors at Texas A&M University used to talk about making rose soil on your own. It was pretty sound and simple: Mix together equal parts of loamy soil, sharp sand, and organic matter - preferably compost or humus. But, in the past, there weren’t many soil yards around where you could get those ingredients in bulk to blend your own.
Now, just about all of them make a rose soil or azalea soil. Some have landscaper mixes as well as vegetable garden mixes. Name a specific planting medium and these days someone makes it in bulk and bags. So, although we’ve come a long way in soil development, I’m still baffled why anyone would try planting a landscape or vegetable garden in our existing soil. I’m equally mystified why people use peat moss or plain old potting soil in outdoor beds and landscapes.
Building The Raised Bed - Landscapes
I can make this very simple. You buy rose soil, build it up 10-12 inches and lock it in with some kind of stone, rock or landscape timber. Thanks! Drive safely, and we’ll see you soon.
Okay, it’s a bit more detailed than that, and there are nuances along the way.
Let’s start with the basic technique - tilling a few inches of rose soil into the existing soil, then building the rest of the bed on top of that. While that may not be not necessary when transplanting a one-gallon or smaller plant, some come in 3-, 5- and 15-gallon containers. Ten or 12 inches of rose soil is simply not going to be enough for something in a 15-gallon or larger container. So, you’ll need to dig into the clay soil. If you till several inches of rose soil into the existing clay, a few inches of a larger transplant’s roots will benefit from the mixed-in organic matter, and the plant will have a fighting chance of success.
Think about it this way: If you dig a hole in existing clay soil and slide a plant into it - like a shotgun shell into a gun - what do you think will happen to the root system as it tries to grow? And boy, do they want to grow. Let me answer that. The roots will wrap around each other and eventually just quit because there’s no place to go. But imagine a few inches of clay blended with rose soil or organic matter, then the raised bed material on top of that. A shrub’s roots are just over 10 inches deep in a 10-gallon container. With the amended area down low, and rich soil in the top 8 or so inches, you can see how building raised beds is the key to landscaping success in our area.
Pretty much each weekend on my radio show, I hear stories from newcomers to Gulf Coast gardening like this: “Randy, I planted a knockout rose last spring, just after moving here from (fill in a state north of the Mason Dixon line), and it hasn’t grown much at all. But my neighbor’s rose is flourishing.” I’ll usually ask how it was planted, and … you guessed it … they dug a hole in the existing soil and slid the plant right in that clay tube. Have you ever looked at the delicate roots of something just slid from a container? How in the world could those feather-light roots penetrate that clay wall?
What About Existing Beds?
Over the years, many have asked me if they can convert existing beds to raised beds. The answer is complicated. It’s not just a YES or NO. So, here are some basic rules for trying a transformation.
First, extract all existing smaller shrubs and landscape elements and start overusing the bed-building steps above. Second, occasionally aerate the soil while adding good mulch, soil activators and micronutrients. You can accomplish this over time by updating mulch levels with organic products like compost or native products at least twice a year, and poking holes occasionally with something like a piece of steel rebar or a metal rod. I also encourage spraying or soaking in a soil activator or liquid organic food a few times a year.
You can leave larger shrubs in place and build raised beds adjacent to them, where smaller new plants and flowers have a better chance at succeeding. However, if the larger shrubs and trees don’t grow, re-set them.
Building the Perfect Beds – Vegetable Gardens
I have a simple answer here as well. Mix two parts rose soil to one part quality compost and make a raised bed of 10-12 inches. Boom! That’s all you need to know.
Yeah, I know it’s not always that simple. But it can be. I’m not here to argue with commercial growers about the need for raised beds in vegetable gardening. I completely understand that they incorporate sand and organic matter in the fields they have worked and amended for years. My advice is for typical homeowners in the suburbs of Southeast Texas. And that means we build raised beds, plain and simple. And when we experience warmer-than-normal winters, we also need to get busy building vegetable beds as early as possible.
For years on GardenLine and in my books, I've tried to make it as easy as this: Make a raised bed of good garden soil — equal thirds of soil, sand and humus (rose soil) — as the starting point. It should be at least 6-8 inches, but 10-12 inches will be even better. Then, amend that with well-composted organic matter, humus or manure at about one inch (tilled in later) to every 4-6 inches of good soil. These days, though, there's an even simpler recipe: Two parts rose soil to one part compost. Then, lock it in somehow. Use timbers, lumber, cinder blocks or landscape stone. Just lock it in!
Most people I know who use this technique don’t even try to kill the grass or weeds in the area. You can suppress grass or weeds with 8-12 layers of newspaper, covered by the soil and compost. Over time, the paper will break down and become part of the soil. In the meantime, it prevents weeds and grass from growing up through your pristine vegetable garden. Best inside advice when doing this is to wet the newspapers so they stick to the ground below and don’t move when you start layering on the dirt.
You don’t have to cover the top layer with mulch unless you want to suppress weeds and conserve moisture. But I simply use compost as my mulch these days, and that’s adding more organic matter to the raised bed over time.
While I’m at it, let me encourage you to learn my “Top 10 Rules to Live By” for Texas vegetable gardening. While the first key to success is the right soil, following the rest of these tenets will virtually assure your success.
- 'Tis better to plant a 25-cent plant in a $5 hole than a $5 plant in a 25-cent hole. In other words, build proper beds.
- Compost, humus, or organic matter - You say tuh-MEY-toh, I say tuh-MAH-toh. Whatever you call it, it's a wonderful thing. Use it!
- Ensure good drainage - With our feast-or-famine rainfall, you'll eventually see why this is so important. Or you'll drown your first attempt in a gully-washer.
- Let the sunshine in - Pick a spot that can provide up to 6 hours of sunshine. Filtered light won't cut it.
- Pick proven varieties - Be sure it's approved for our growing region. In fact, check with your county extension agent for proven varieties.
- Cheat Mother Nature - Because of our heat, if you can start 'em early, more power to you ... especially if you're willing to protect them on late-freeze nights.
- Control your appetite - Don't over-plant; rein in that desire.
- Feed me, Seymore!!! - Veggies are heavy feeders (Just ask the Audrey II). The compost is a good start and a nice addition throughout, but amend that feeding with some kind of fertilizer, be it granular, liquid-organic or water-soluble.
- Keep your shadow in the garden - Get out there on a consistent basis, looking for insects, weeds and diseases. An ounce of prevention is worth a pound of cure.
- Consistency, consistency, consistency - Regular watering and repeated feedings are critical. Don't ever allow things to dry up before you water.
The 10 Commandments of Mulch