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What Your Garden's Weeds Can Tell You About Soil Health

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There are several good ways to determine how healthy your garden's soil is. The most reliable way is to have your soil tested by your local cooperative extension service. You can also conduct a few different DIY soil tests to determine what kind of soil you have and how quickly it drains. Another good method is to observe what is growing well there. Specifically, which weeds seem to absolutely thrive in different parts of your garden? We're not talking about one or two scattered weeds; we're talking about seeing large numbers of the same weed in a concentrated area. This can tell you a lot about your soil, and give you an idea of what you need to do to fix it.

What Your Garden's Weeds Are Telling You

Here are a few of the most common lawn and garden weeds, and what they may be telling you about your soil:

  • Bindweed: This vining plant with white and pink blossoms is a relative of the morning glory (and a major pest, to boot). It thrives in compacted soil. If you are seeing high numbers of this plant, it's time to consider double digging the area and add a good amount of compost or manure to the area.
  • Chickweed: This low, spreading weed is a sign of high fertility. It is common to see it in lawns that receive lots of high-nitrogen fertilizer. Consider cutting back on the fertilizer; chances are good that you're over-fertilizing anyway if you use synthetic products. Chickweed also shows up in consistently moist and compacted soil; consider tilling and adding compost.
  • Chicory: Chicory is most easily identifiable by its bright blue flowers. This is another plant that shows up very often in compacted, neglected soil. You know the drill: double-dig or till, and add compost and/or composted manure.
  • Dandelion: Probably the most easily identified weed, the dandelion is common just about everywhere but will absolutely thrive in acidic soil. Here are some tips for improving acidic soil.
  • Henbane: Henbane is common in the northwestern U.S. as well as southern Canada. It is a sign of alkaline soil. Improving alkaline soil takes some time, but you can get a good start by incorporating six inches of compost per year into the top foot of soil. Over the course of a few years, the pH will improve.
  • Lamb's Quarters: Lamb's quarters are very common annual garden weeds. Their presence is a sign of high fertility. Ease up on the fertilizer if possible.
  • Plantain: There are several different types of plantains, from round-leaved varieties to those that have foliage that resembles grass. If they're flourishing in your garden, that's a sign that you have low soil fertility. Start incorporating more compost and manure into the soil in the area. If it's a lawn, topdress with finished compost in the spring, and give the lawn a monthly feeding of fish emulsion.
  • Purslane: Purslane's fleshy leaves are actually a good source of omega-3 fatty acids, iron, and calcium. If it's thriving in your garden, you probably have soil that is high in fertility. Ease up on the fertilizers, if possible.
  • Quackgrass: This grassy weed, which is a perennial that spreads via rhizomes and suppresses the growth of other plants with its chemical secretions, is a sign of compacted soil. Double-dig or till the area. If it's a lawn area, you could try renting an aerator from your local home center; these machines remove plugs of soil, opening up avenues for air flow and water and giving the roots room to grow.

A huge part of being a successful organic gardener is simply paying attention. Observe your garden regularly. Paying attention to what thrives in your garden will help you learn more about your soil. And, since the soil is the most important part of any garden, you'll be a step ahead!

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