Controlling Weeds: Annual vs. Perennial Weeds

Different weeds require different action

Ivy growing on a field
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If there’s a bare spot in your garden, a weed seed will find it. Weeds aren’t bad plants; they’re just plants growing where you don’t want them to. Some weeds are easily removed by hand. Others are persistent about growing back and become more and more difficult to eradicate the longer they are left to establish themselves and spread.

Annuals Versus Perennials

Just like plants you intentionally grow in your garden, weeds may be annuals or perennials. In general, it's much easier to eradicate annual weeds than perennials.

  • Annuals are plants that sprout from seed, grow for a single year, and then die. Typically, annuals produce many seeds that can germinate to produce more plants the following year.
  • Perennials, by contrast, are plants that establish deep roots and continue to flourish year after year.

Annual Weeds

Annual weeds spread throughout your garden by seed. They may self-seed or they may be brought into the garden by birds, by four-legged animals or by sticking to your clothing as you walk by. Examples of annual weeds include bindweed, chickweed, crabgrass, knotweed, lambs-quarters, mallow, pigweed, purple deadnettle, groundsel, nettle (common), purslane, speedwell, spurge, and yellow oxalis.

Just as with other plants, there are weeds that favor cool weather and cool-season annual weeds, and there are warm-season annual weeds.

  • Cool-season weeds sprout any time from fall through spring. They’ll go to flower in late spring / early summer. The plant may disappear when the weather warms, but you’ll see even more of them germinating the following fall.
  • Warm-season weeds tend to start growing in the spring and hang around all through the growing season. Either way, the only way to control annual weeds is to get rid of them before they go to seed again. Luckily, annual weeds very often have shallow roots and can be easily hand pulled or cut off with a hoe.

Hopefully, you will see fewer and fewer annual weeds as the season goes along. The reality, however, is that new seeds will always find their way in and some seeds remain dormant in the soil until ideal conditions present themselves and they germinate. Weeding is an ongoing process; if you can get in the habit of doing a little weeding each time you work in your garden, it won’t become an overwhelming task.

Perennial Weeds

Perennial weeds are the most difficult to get rid of. They spread by both seed and creeping roots and if you don’t pull the entire root, the plant can actually reproduce from every little root piece left behind. You’ll have similar problems with perennial weeds that grow very deep, hard to remove taproots.

Hoeing and tilling are not good choices for removing perennial weeds. Hand weeding will work if you are very thorough about getting the whole plant and root system. If you can handle the cold, perennial weeds pull out most easily in the early spring, when the ground has recently thawed. Sometimes herbicides are the only solution for eradicating tough perennial weeds like poison ivy, ground ivy, and brambles.

Examples of perennial weeds include bindweed, burdock, dandelion, dock, ground ivy, horsetail, Japanese knotweed, plantain, poison ivy, purslane, quackgrass, thistle, and ragweed.