By Nancy Downs, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County
There is more to a good-looking landscape than plants. Here are some tips about other materials that go into creating the perfect garden.
To spray or not to spray.
After you decide on the sizes and shapes of your new beds, the next step is to remove all the unwanted vegetation within them. Wrestling out old junipers and attacking weeds is one of the least appealing aspects of putting in a new landscape, but doing a thorough job of it is the only way to prevent your new garden from being overrun with grass, weeds, suckers and re-growing shrubs before the end of the first season.
You have to dig out the woody plants, but for grass and weeds, you can choose between digging them out or spraying them with a non-selective herbicide. People who object to spraying usually do because they believe the spray is harmful to the environment. Glyphosate products (like Round-up) are supposed to break down into harmless elements quickly. Whether thats true or not may be debatable, but how does stripping off grass and burying it in a landfill fit in the grand scheme? It seems vaguely disturbing to haul off one organic material (grass) only to buy another (say, compost), both of which would improve the soil structure.
In any event, an important advantage to spraying is that you will kill perennial weeds like mallow, bindweed, bluebells and dandelions. If you only scrape off the tops, they will re-grow from their roots.
Preparing your soil.
Adding an organic soil amendment, like compost, well-rotted manure or spaghnum peat moss, will loosen up clay soil and improve drainage. At CSU, the rule of thumb is to add 3 cubic yards amendment per 1000 square feet of soil, but you can test your soil for a more individualized recommendation. On the other hand, if you plan to grow only native plants, leave the soil as it is. Most people seem to want shade and ornamental trees, some shrubs, a little lawn and a few perennials, all of which will benefit with soil amendment, so I say go for it.
Spread the amendment a couple of inches deep over the new bed and till it into the soil about 6-8 inches deep. Depending on the size of the area and how long its been since it was last worked, use either a shovel or a rototiller. A word to the wise: when we dug up my front yard, it had been in grass since the house was built in 1924 and was like concrete. The rototiller barely penetrated.
Edging is not a moat to hold in the mulch; edging is a barrier to prevent grass, which spreads by roots underground, from creeping into your bed. Consequently, to do any good, the edging has to be wide enough to be sunk 5 or 6 inches deep into the soil, with the ends overlapped 4" and secured with edging pins.
Ideally, you would use 6" x 10 14 gauge black steel but I have yet to see it sold retail. The 4" steel sold by nurseries isnt wide enough, and the plastic stuff sold at home improvement stores is a waste of time. As an alternative to edging, dig a 6-8 inch deep trough around the bed and fill it up mulch (so the wheel of the lawnmower doesnt fall in). It works just fine and is cheaper.
There are many arguments for and against the use of landscape fabric. One functional argument against using it in a planting combining woody plants, herbaceous groundcovers and bulbs, is that the fabric prevents the groundcover from rooting as it goes and you wind up with so many holes in it that youve destroyed the integrity of it as a weed barrier. That said, if you choose to use it, lay it down like a blanket, turn the edges under and secure it with landscape pins.
After planting, mulch all the beds with 2 to 3 inches of mulch. There are different kinds, so choose the one you prefer. Shredded or chipped bark looks softer than stone, and doesnt heat up as much, but pea gravel works well, too. There is a shredded wood product on the market that is recycled lumber, dyed, which is all the wrong color in the landscape, but probably good from a politically correct standpoint. Leave a couple inches breathing room between the stems and trunks of the plants and whatever mulch you use, as one purpose of the mulch is to retain moisture, and it can do such a good job that the crown of the plant will rot.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010