While annual weeds such as chickweed and pigweed have many control options, including eating them, keeping perennial weeds out of your garden is trickier. Perennial weeds are tough because they can form new plants along their roots, so even if you pull out most of the plant, what's left behind in the soil will eventually send up a new shoot.
Here are three ways you can deal with perennial weeds:
Evaluate the situation
If perennial weeds have overrun your flower garden, it might be better to transplant the flowers and start over. If there are only a few weeds in the bed or they're just starting to invade try to weed frequently, especially after rain when the ground is soft.
Pick places where weeds can grow
For new areas or places that you want to reclaim, draw a line in the sand or in the clay and decide where the weeds can grow and where your garden starts. Cover the garden spot with black plastic, old rugs or some other heavy material and mow every few weeks to weaken the plants.
Practice good post-season garden care
After a season, pull out the weaken plants, and as much of the root system as possible. Weed thoroughly every year to catch any strays and dig trenches and create a metal, wooden or plastic edge between your garden and the wild weed patch to prevent it from re-invading.