Replacing Turf with Beds and Creating New Beds
The presence of beneficial microorganisms is all-important for immediate success. Letting the soil in the new bed settle and the biological soil life begin to work together is optimal. Like any community, the soil community would like time to get to know each other. This is my preferred method. When I plant anything in soils teaming with a healthy soil food web, the plants quickly establish and my maintenance time diminishes. The microorganisms and soil have all the materials to get the new transplants off to a healthy start.
Landscape beds should properly begin months before the actual planting, but success can still be attained when everything must be done quickly. Just don’t expect the new plantings to establish as quickly, you’ll need to spend more time tending them.
There are some differences in preparing beds for different purposes as mentioned earlier. Landscape beds and borders for low water-use natives and adaptables require minimum amending. Medium and high water-use plants require more extensive amending. Preparing caliche soil for planting requires the most work and amending.
If you are planning on replacing bluegrass, fescue or ryegrass turf with a vegetable or flower border, bed or garden, a low maintenance technique to use is smothering to kill the existing turf. Place several layers of newsprint over the turf. If you have clay soil, weight this down with sand or other inorganic amendment, then compost or a topsoil/compost mixture to a depth of 4 – 6 inches or more, depending on the plants you have chosen. Do not use peat or potting soil mixes to amend the soil.
The smothering layers of newsprint and compost/topsoil will kill the turf in a matter of weeks if done during the warm months, or over winter. It's not necessary to scrape off the sod. Break up the clods with a fork to work in the sand/topsoil/compost mixture. Moisten the bed and let the bed rest and settle 2-4 weeks. Turn over with a fork or rotor till for a smoother looking bed. If necessary, repeat this step, adding more amendments depending on your choice of plants.
The lowest water-use and lowest maintenance beds will only require you to just dig a hole for your new xeric perennial or shrub without working the entire bed area. I might use this method if planting a large area in a naturalistic style using native plants that grow in the existing soil.
Herbicide Carryover and Killer Compost
Read here about herbicide carryover and killer compost.
Bermudagrass Removal -- A Rare Exception
Killing bermudagrass with a synthetic chemical is a rare exception to my organic program, but I think, necessary. However, as with anything, someone will note they have removed bermudagrass using the lasagna method. In most cases, using a synthetic chemical may be the better method. Due to its invasive and persistent nature, bermudagrass turf areas will need to be killed with a glyphosate-based herbicide such as Round-Up. Two applications or more may be necessary, two weeks apart during its growing season. These herbicides work better when the plant or grass is actively growing and not under stress. Allow a minimum of 2 weeks after the final spraying before seeding or planting.
In an organic program, the guiding philosophy is to not destroy the microbial life. In choosing what methods to employ, this should be taken into account. If you already have a thriving beneficial microbial population, this will only temporarily set it back. Rejuvenate the area with an application of worm castings, good quality compost or other microbe stimulator. One of the main problems with using chemicals, whether organic or synthetic, is that gardeners rarely rejuvenate the soil afterwards, and use chemical remedies repeatedly. These practices do not allow for the normal, natural continuance of soil beneficial microbial life.
If your hardpan is close to the surface, it's best to loosen the hardpan. It's a good idea to break up the bottom with a pick ax or garden fork. If you are taking out soil and then bringing in a topsoil/compost mix, it is helpful to know that a cubic yard of sand, topsoil, mulch or compost, will cover approximately 108 square feet to a 3 inch depth. Mix some of the compost/sand/topsoil mixture (whatever you have decided you need) into the existing soil before adding the rest.
Another method to eliminate hardpan or improving drainage is through double digging a bed. Measure off your bed and dig a trench about 1 foot wide by 1 foot deep, piling the soil in a wheelbarrow, tarp or ground cloth. If you're removing sod, shake as much soil from the clumps as you can and set the sod aside to compost later. Loosen the subsoil with a garden fork or pick axe.
Sprinkle elemental sulfur at the rate of one to four pounds per 100 sq. feet to loosen heavy clay soils and hardpan. Add your compost or inorganic material to the top. Mix it a little. Start another trench and toss the soil from the second trench into the first trench. Layer into the first trench some compost/inorganic amendment mixture as you go.
Repeat these steps until you have finished your bed. Then add the topsoil from the first trench to the last trench you dug, layering in the compost/sand mixture. Moisten. Your beds will be 3 – 6 inches higher than when you started. Some of this will settle with time, but treat it as a permanent bed.
A Design Element
If you have a square, rectangular or linear area, a dry river bed with accent and river rocks could be used to create visual interest and draw the eye away from the stark rectangular nature of the bed. A series of mounds and a pair of bends in the river joining up could also be implemented. This is also an ideal technique for channeling drainage from rooftop drains a bit more esthetically -- with a regional look.