I did the following in an open area of Bermuda grass that I wanted to convert to garden beds. It took time and diligence, but it was successful. I did this over the course of the summer, winter, and following spring. I began the first week of July:
1. Till up the area to your tiller's deepest setting. Make sure you go back and forth, crosswise with your tilling. Most tillers leave an untilled swath between the tines. You want it all tilled.
2. Rake out every bit of bermuda - top growth, rhizomes. Note: you won't get it all, but you'll get about 50-75% of it.
3. Keep the area moist. The Bermuda will start re-emerging in a few weeks.
4. Till it again, as dutifully as in step 1.
5. Rake out every bit of Bermuda you can. You will note you will be removing far less this time than after the first tilling.
6. Again, keep the area moist. Bermuda will begin re-emerging in a few weeks. By this point, you can determine if it is worth tilling or going after it by hand. If you choose the by-hand method, the pulling will be pretty easy as what you will be pulling will be the rhizomes that are not anchored into the underlying soil.
7. Maintain soil moisture and continue digging/pulling bermuda as it sprouts. You will continue to do this into the fall, until what bits of Bermuda have gone dormant.
8. In the late fall, plant a crop of fava beans on a 2 foot wide spacing and mulch heavily with leaves, preferrably shredded. The favas will help with some of the nutrient damage you've done to the soil with the tilling. It will also provide spacing to see any sprouting Bermuda in the spring when the soil warms. The leaves will prevent/minimize erosion.
9. The following spring once the rains subside and the sun really begins to shine, rake back the mulch and allow the sun to warm the soil. Cut down the fava bean plants and go after whatever Bermuda comes up. If you've been thorough the previous fall, there won't be much but sporadic sprouts will inevitably be there. But your war should largely be won, and you are not down to smaller post-war battles that can be handled with garden shovel and continued diligence.
10. Your first crop in the late spring should be something like peppers or eggplants... something that can be planted with a heavy mulch of straw, and allows space between plants. Keep the garden bed moist, not just each individual plant. You want to give any lurking Bermuda an opportunity to re-emerge over the course of the summer. Your job through the rest of the season is to go after any Bermuda that emerges through the straw. Even if it means sacrificing an eggplant or pepper plant to get to the roots, then make that sacrifice. You're trying to get rid of Bermuda and growing a few veggies at the same time. Same thing you did with the favas. If you are diligent, you'll be BErmuda free by the second year and focused on growing food, not battling Bermuda.
Yes, this method is time consuming (meaning, longterm) and indeed hard on soil structure due to the tilling. I did it this way three years ago on what amounted to a thick, lawn-like patch of Bermuda. After the one year war, I placed raised garden beds (2X6) on top, added compost, manure, soil from other parts of the yard. It's year three, and I've had only 3-4 instances of a stray Bermuda sticking its head up. Considering my starting point, not bad. And I know there's a few folks reading who would frown on the tilling I did, but longterm, the beds are now no-till, so it was an intentional one-time war that avoided herbicides that would remain in the soil longterm.
Anthony
Citrus Heights (suburb of Sacramento)
www.thecookhousegarden.com
