Thinking it through: Bed prep by killing vegetation

There are two basic methods.

One, apply a herbicide.

Generally, this is done with a systemic chemical. The plants absorb it and self-destruct. The chemical of choice is often glyphosate (active ingredient in RoundUp and other products) because it isn't likely to taint the soil and ruin a subsequent planting.

However, "burn down" herbicides are also unlikely to cause carry-over damage. However, since their mode of action is the chemical equivalent of repeated hoe-ing and most turf can survive at least one scalping, multiple applications of burn down products are necessary to kill established turf.

Worth noting: If plants are not in active growth, standard systemic chemicals do not kill them. The plants remain alive, in place -- perfectly positioned to become entrenched weeds. Examples of plants that can escape: Bulbs or spring ephemeral species can escape summer herbicide application; warm-weather, late-emerging weeds such as milkweed can escape spring application; lawn in heat-induced summer dormancy.


Two, smother to kill

Cover what's growing there, blocking the sun. Keep it in the dark long enough and the plant exhausts its stored energy and dies.

Our rule of thumb: Smother by May 1, you can probably plant in September. Smother by September 1 and you can plant the following May. More on smothering in What's Coming Up 95 pages 6-8.


Simpler but sweatier

The simplest solution is often to remove the sod -- dig it out -- even though it's more labor intensive and generates material to be disposed. On the "plus" side: It allows you to plant right away -- no waiting for plants to brown and die, or waiting periods as repeat rounds are aimed at surviving weeds. It also makes grade changes simpler. A change in grade is often necessary where sod in a narrow area has become elevated and would create an unfortunately mounded bed.