Heed the Weeds: What Weeds Tell Us About Soil

Heed the Weeds: What Weeds Tell Us About Soil

While weeds are often seen as a nuisance in the garden, and while they can compete with your vegetables for nutrients - you may want to pause for a moment before eagerly pulling them out of your garden beds. In nature, nothing is random or accidental - and weeds are no exception. The varieties that grow, how quickly they sprout and spread, and how healthy or unhealthy they appear can provide valuable information. Weeds can be extremely helpful to gardeners in determining any potential issues in the soil. So, before grabbing your weed-pulling tool from your garden shed, take a moment to closely examine which ones are popping up around your property.

A lady pulls weeds up from her garden

First, we must acknowledge that weeds are, in fact, just plants growing where they are not meant to be growing. Nature has a way of reacting and adapting to its surroundings and environment. When things are off balance or when the environment is disturbed, nature will attempt to resolve the issue itself by focusing its energy on a return to stability.

While soil testing would be the most fool-proof and accurate way to know the exact composition of your soil, the information you can garner just by paying attention to the weeds will give you a very good preliminary assessment. Soil drainage issues, pH levels, nutrient levels, fertility and compaction are all factors that can be determined by monitoring the weeds.

Weeds can also be a good indicator of the soil being warm enough for planting - when you begin to see weeds sprouting up in your garden beds, it is time to sow your early crops! 

Common Soil Issues and the Weeds They Produce

Alkaline Soil means that the soil has a high pH level. While some crops do well in alkaline soil (cabbage, cauliflower and broccoli to name a few), this higher pH level can actually make nutrients in the soil less bioavailable to plants and prevent absorption. Higher pH levels can also stunt foliage growth or cause leaves to appear wilted or spotted. Some weeds indicating your soil is alkaline would be Salad Burnet, Wild Carrot (also called Queen Anne’s Lace) and Chicory.

Wild carrot, also known as Queen Anne's Lace

Neutral pH levels are considered good for the soil, and many crops will grow well in neutral pH - but certain weeds will also thrive. Daisy, chickweed, and purple deadnettle are among the weeds that do especially well in neutral soil and could be a good indicator that your pH levels are actually in balance. A soil with balanced pH will allow most crops to go well, with a few exceptions like blueberries, raspberries and rhubarb.

Acidic Soil can be characterized by a low pH level. When the soil leans more toward being acidic, you may find an abundance of buttercup, horsetail, mullein, or sheep sorrel. A common way to neutralize acidic soil would be to add lime and compost high in organic matter. Acidic soil can diminish the uptake of nutrients and prevent plants from accessing the water in the soil effectively. It can also lead to nitrogen leaching and make soil more prone to erosion.

Dry Soil may seem like it cannot grow much vegetation, but certain weeds will still grow in an attempt to attract more moisture. Mustard, pigweed, thistle, and yarrow tend to break through dry soil and can be difficult to control as long root systems are designed to grow far and deep in their search for water. Using a soil amendment that contains humic acid and fulvic acid will help to retain moisture in the soil and add structure to prevent it from drying out.

Thistle weed grows well in dry soil

Compacted soil may have difficulty growing healthy crops, but will encourage the growth of dandelions, clover, quackgrass, and knotweed. Soil can become compacted when it is subject to foot traffic, when it is highly tilled, or when it has been left bare to the rain and then worked while wet. Avoid overworking soil if you notice it is getting compacted, try adding in aeration by poking in some holes with a garden fork and add in some organic matter or a bit of sand.

Low Fertility soil is typically deficient in essential nutrients and organic matter. It will not have the binding qualities of fertile soil and will crumble and erode easily. Spotting weeds such as crabgrass, mugwort, ragweed and vetch can indicate that your soil lacks the nutrients that would make it fertile. These weeds tend to draw nutrients toward their root systems to fix them in the soil to increase fertility.

Fertile Soil can also grow its fair share of weeds, but you may want to think twice about pulling them up and simply discarding them. If you notice stinging nettle, purslane, or lamb’s quarters in your garden beds - consider yourself lucky! Not only is your soil healthy and fertile, but these “weeds” are actually edible, highly nutritious, and medicinal. They have also been doing their part to bring nutrients up closer to the rhizome where they can be absorbed - so you can be confident that whatever crops you plant in this soil will be well-fed. 

Making use of what nature provides

Many plants we consider common weeds have been used for centuries in herbal medicine due to their healing properties. Once you know which weeds are growing in your garden and what they are telling you about your soil, you can decide if you want to remove them completely or allow some to keep growing and make use of them.

Dandelions are one of the most nutritious plants you can find and are used medicinally worldwide for various ailments. Every part of the plant is edible from the root to the flower. Harvest the leaves for a nutrient-dense salad rich in vitamins A, B, C, E, and K. The roots can be cleaned and dried to make a tea or coffee substitute. The flowers can be infused into raw honey to help treat asthma or respiratory infections.

Stinging Nettle can be harvested (while wearing gloves!) and made into an anti-inflammatory tea or sauteed as a nutritious and delicious side dish. It is high in calcium, magnesium, and dietary fiber.

Be sure to wear gloves when pulling up stinging nettle

Yarrow can be applied to the skin to stop wounds from bleeding and help accelerate healing. It can also be ingested for heartburn or indigestion relief and works well as a diuretic.

Mugwort can be used as a laxative, liver tonic, and sedative. It has also been said to enhance dreams when taken as tea before bed.

Lamb’s quarters are edible and highly nutritious as they are high in protein, fiber and contain vitamins A and C. They also have a high calcium content, can replenish the body’s iron, and are a source of omega-3 and 6. For relief from insect bites or inflammation, they can be chewed into a paste and applied to the affected area.

How to deal with unwanted weeds

It is not uncommon to see rapid weed growth in garden beds where the soil has been disturbed - this is because the weeds are attempting to repair the damage caused by tilling and trying to restore balance to the barren area. Take note of which weeds pop up at the start of the growing season, and harvest those you can use. Once you have a good assessment of your soil and which weeds grow in abundance in your garden, decide how you want to proceed with weeding.

One way to reduce the number of weeds is to cover your garden beds with cardboard or a plastic tarp a few weeks before you plant, cutting off the sun exposure and killing off a good portion of the weeds. Once you remove the covering, apply a layer of quality compost and then plant your seedlings. Mulch around seedlings with a natural mulch like straw, grass clippings or dried leaves. The nutrients in the compost and the organic matter will help to restore soil and balance pH levels. You may still need to occasionally pull weeds, but the task will be made much easier.

Pulling up weeds in the garden

Staying on top of weeding from the start of the season, doing a little bit every few days, will prevent the weeds from getting out of hand and competing with your garden crops. If you prefer a weed-free garden, try your best to pull out the root of the weeds to prevent them from re-growing. If you can pull the weeds before they go to seed, leave them to dry up on the soil's surface, acting as a mulch that will return nutrients to the soil as they decompose. If you notice that they have started producing seeds, it is best to discard them so to avoid an abundance of germinating seeds that are sure to quickly take over your garden.

While keeping a tidy, weed-free garden can be a tempting goal, leaving some weeds in the ground can benefit your soil as they help uptake and cycle nutrients. Using some of your garden weeds as food or medicine is a great way to make the most of what nature can offer. While you want to provide the best possible environment for your crops to thrive, you may also not have the patience to pull weeds up every few days, and we all know that using weed-killing chemical treatments can do more harm than good. Finding a balance that works best for you and fits well into your lifestyle is the key to any successful gardening venture.

Posted in: Gardening, Humic Acids, Soil Health

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