In most of Texas, it is essential that we build beds to plant things like landscape shrubs and vegetable gardens. That's because in most of the state, our soil simply stinks. It's got too much Clay, or Gumbo, or Sand or Caliche. Whatever the case, it's not the best soil to plant anything in without amending it.
Which is why garden-advice gurus such as myself are always hammering home the point about "building raised beds." Unfortunately everyone seems to want to build a raised bed in the existing soil. STOP THAT! Building a raised bed really does mean building a bed on top of whatever you have that stinks.
So, here are some simple steps to remember when building a raised bed. Again, this is almost always needed for landscapes, vegetable gardens and flower beds. These techniques are never recommended for Tree Planting.
Let's start with the soil: The best soil simply put is Rose Soil. Rose Soil is normally a perfect blend of Clay-soil, sand and well-composted humus material. They sell it by the bag and by the bulk at many soil yards. If they don't have a Rose Soil, then ask for a blend that may be called a Garden Mix, or Landscaper's Mix. This too, is usually a perfect blend of the aforementioned elements -- Soil-Sand-Humus. A raised bed needs to be at least 8-10 inches above the existing soil profile. But it can be mixed for a few inches with the existing profile. But that also means if you blend the Rose Soil with the existing soil, you still need to add 6-8 inches of nothing but the mix on top of that which has been blended with the existing soil. Again, the goal is to achieve a raised bed.
Then it's important to lock it in. You can do that any number of ways, but don't just build the beds and forget to lock it in. I am a personal proponent of Landscape Stone, as seen in the picture at left, to "lock-in" these beds. You can also use landscape timbers or pre-cast bricks akin to cinder blocks. You can use the "edging material," you know, the 4-6 inch green metal strips? But, unless you're desperate please avoid the edging. Not only does it look "20-years-ago" but they also always come loose and they always rust.
As for landscape stone, there are many kinds and many colors, and I really don't care which color you choose, just make sure to contrast the color of the brick or paint on the house. Never, ever try to match the color. Landscape stone is also known as Moss Rock and it can also be found in Limestone.
Up against a house and near the foundation, it's never a good thing to make a raised bed right up over the weep holes of the foundation. It is a good idea to lay a few inches of bull rock or river rock up next to the foundation. And then you can start your raised bed out from the edge of that protective barrier. This serves many useful purposes. First, it keeps you from covering the weep holes. Second, it helps you keep a "walking" area on the back of the landscape bed for cultural-care purposes.
Plus, a raised bed doesn't have to be 10 inches throughout. It is important for it to be at its highest "raised" depth towards the center, where you plant on planting the shrubs. Raised beds can taper down both towards the front and back to as little at 4 inches if need be.
However, if you build a raised bed, and a tapered one at that, and don't lock it in as discussed earlier, you will eventually see it erode away over a period of time.
More specifically, for vegetable gardens (picture at top of page), a raised bed can start with the Soil-Sand-Humus combo discussed earlier, but should also be amended even further with organic matter like well-composted cow manure or cotton burr compost. I say the perfect blend for a raised veggie garden is the two parts Rose Soil, blended with one part organic compost. Or seen another way, 1/3 of your soil needs to be really good compost.
Then there is the basic and true Flower Bed. Again the bed should be raised, but probably no more than 4-6 inches. However, do not apply this rule to the base of trees. If you follow my advice, you should never try to plant things around the base of trees, especially flowers. The only exception to this is that ground covers, which are mostly permanent, can be planted around the based or in the mulch rings of tress. A raised "flower bed should be all on it's own.
Lastly, no matter what bed your building, cover it up with a nice thick layer of mulch. What kind of mulch is up to you, but let me say this about "building raised beds" - If you ever want to continue to build upon that bed by naturally adding organic matter over time, you must stick with the shredded mulches: Shredded Hard Wood, Shredded Pine Bark or Shredded Texas Red Cedar. As they tend to decompose while they are doing good things like blocking weeds and conserving moisture, they tend to naturally build back the soil profiles.
Until next issue, here's to
Great Gardening from the GardenLine, heard
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