Hi Jamie, Nice to hear from you. I really enjoyed my visit with you in Bellingham! It's really hard to generalize about weeds since conditions are so varied. Often they exist as "invasive" because of something people are doing, most commonly tilling the soil. When you do that you not only stir up seeds deep in the soil but you also set succession back to time zero. Nature seems to abhor bare ground so it is covered up as soon as possible by plants that have an advantage under those conditions. So the first two things you should consider is what might I consider discontue doing that is causing the weeds to get so strong, and how might I improve the soil or otherwise change things so those problem weeds will no longer have an advantage. In Gaia's Garden, for example, Toby gives the example of bindweed, one of the most difficult weeds in the PNW. It does particularly well in poor soil and that is generally what we create by our activity. Once he was able to improve the soil by using mulch and a permanent ground cover, the bindweed lost its advantage and disappeared.
Typical conventional permaculture techniques would be STOP PLOWING, mulch, sheet mulch, permanent ground cover. Fukuoka-san said that dealing with weeds was his most difficult challenge while he was creating his natural farming techniques.
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