Are weeds just weeds?
Weeds in the garden can seem like a never-ending task to deal with. Pulling. Hoeing. Cutting. Ploughing. Chopping. It gets exhausting! Having spent many an hour out in the field pulling those countless weeds, I feel your pain. After a few years of weeding, there are patterns that I began to notice that opened up my eyes to the secrets weeds hold about your garden. If only we took time to observe, even the unwanted plants have a way to tell us what the soil is lacking.
Before we dig into the secrets of weeds, let’s learn a little bit more about them. Weeds are essentially any plant that is in an unwanted location. For us, mint is a weed as it spreads and moves to unwanted locations. The purpose of weeds is to help keep the soil covered and prevent runoff. This is an incredible ability for the land to heal itself. While they may decrease yields and prove a nuisance in the garden, weeds have an essential purpose in the natural ecosystem, from which we can learn some helpful tips.
Benefits of weeds
By keeping the soil covered as weeds do, it can greatly increase soil moisture retention levels. Weeds also help hold the soil in place with their roots, preventing runoff. Both moisture retention and runoff prevention are excellent characteristics to pursue in a garden, but we can sometimes obtain the result without a heavy investment into tools, resources, or infrastructure. My favorite way to mimic the weeds in nature is to multi-crop each section of the garden. A great example is planting carrots next to tomatoes to maximize crop space while holding the soil in place.
You can find some other examples from our post on the top 5 companion plants for tomatoes.
What are weeds?
Beyond their functional role in the ecosystem, weeds can also tell us a story about the soil’s health and needs. Whether you have too little or too much nitrogen, phosphorus, or calcium, the presence of certain weeds can give you an indication of what your soil needs for its chemistry. And likewise, certain weeds prefer to grow in compact or dry soils or soils that are acidic or basic.
Based on what weeds are present and where you can get an idea of how your soil is doing around your garden! This is not 100% accurate and getting a soil test is still a good idea. But it has helped us create a more consistent garden from the soil perspective.
Which weeds are what?
Before we can understand what weeds tell you about your soil, it is good to take the time to identify the weeds. I have found identification books helpful to learn what weeds are which. There are apps that can also help you with plant identification, but I have found the rhythm of fingering through a book delightful. The most helpful book I have used is the National Audubon Society American Wildflowers. The vinyl cover makes it durable for field use, it has a great concordance that is easy to use, and it is small enough to carry around the field.
Now into the weeds! This is not an exhaustive list of weeds you may encounter. But rather varieties that I have found on a regular basis in the gardens here. Each one here is linked to different sites to show you that weeds are everywhere. I hope that this list and resources inspire you to look in to the weeds you have in your garden.
Bindweed (also known as wild chicory) are indicators of crusty soil with moderate compaction. They are frequently found on the border of paths or where any runoff of compost reaches the edge of the garden.
Chickweed is one we have frequent pressure from in our garden, which is usually a good sign. This weed grows where the soil is fertile with nitrogen and has a balanced PH, telling us that the ground there is suitable for most vegetable crops. Learning to observe weeds such as chickweed can help you notice what weeds tell you about your soil.
Crabgrass is not good to have, both from a weed perspective but also from what they tell of the soil. Their presence means that the soil is depleted of nutrition and is low on organic matter. Wherever you see crabgrass, it is a good indicator that more compost is needed.
In the low spots of gardens where soil compaction might be higher and water retention more prevalent, curly dock will frequently be present. From nature’s perspective, the large taproots help break up the soil to enable better flow of water and nutrients while also fracturing the soil to decrease compaction. If you desire to eradicate this weed, it is best to do so after a heavy rain as the roots are hard to extract from the soil.
Every year in February here in South Carolina, seemingly millions of henbit plants emerge in the gardens. If you have this particular weed come up in your garden, it is a good sign that you are doing well with your fertility. The best way to prevent henbit is to have either a good cover crop or a thick crop that is overwintering. Otherwise, this weed literally creates a carpet over the soil. This provides a great protective measure to help prevent erosion from the heavy spring rains. But also provides a nuisance, especially around plants that are sensitive to competition. A good example is onions. If there are too many weeds around onions, they seem to refuse to bulb, presenting leggy long bulbs that do not store as well.
As summer approaches, lambsquarters may appear in your garden. Wherever you see this plant in your garden tells you that your soil is rich and high in nitrogen. These would be good areas to plant brassicas, leafy greens, or tomatoes. Root crops would grow beautiful leaves in these areas, but the high nitrogen would inhibit root growth. Best of all, lambsquarters is edible and nutritious! The young leaves can be eaten raw or cooked and some people compare the flavor with that of spinach.
Common mullein is a plant that would be better to not see in the garden. This plant indicates that the ph of the soil is low (often too low for vegetables to grow) and low fertility. If you happen to have this weed, I would suggest adding compost and lime to that area to balance the PH and nutrients in the soil.
There are some weeds that indicate some imbalances of some of the minor nutrients as well. A good example is wood sorrel. It indicates that calcium levels are low but magnesium levels are high, which presents issues if tomatoes are grown here.
Plantain are an interesting plant in that they thrive in compacted sour soil with little fertility. I have frequently seen them along heavily trafficked areas. If this is in your garden, this area could benefit from a good broadforking or planting tillage radishes to break up the soil. A good load of compost and micronutrients could also help this particular area of the garden as well.
In addition to being a major allergen, ragweed also tells you that the soil is lacking in fertility. A good dash of compost, animal manure, and green sand can help remedy this part of the garden.
And last but not least is purslane. This delightful edible weed grows in soils that are rich and are an indicator of higher phosphorus levels. If you have this weed, try to add fertilizer and compost that is lower in phosphorus.
Where to start
If it is a plant that I did not intentionally plant, it can be easy to be ruthless and pull it out. When trying to see what weeds tell you about the soil, slowing down can help greatly. To use the power of observation and watch for clusters of particular weeds. If the weeds are evenly distributed, it is a telling sign that your soil is quite even throughout the garden. But sometimes, particular weeds can be concentrated, often telling a different story. By observing the patterns, you can sometimes discern what the soil needs to help your vegetables.
Continuing to learn
One thing I love about gardening is there is always more to learn. The garden always has more secrets that the quiet observer can sometimes glean. And the study of weeds is no exception. It can sometimes be disheartening or tiring to have to deal with weeds. But the resulting yields and healthier soils are definitely worth the effort. Always remember when weeding to keep an eye on the what, where, and why. What type are they? Where are they located? And why did they grow in that location. These questions can help you understand what weeds tell you about your soil.
It is never to late to learn more about the garden, and I hope that this information is a tool to help you in your gardening journey. To better understand what weeds tell you about your soil.
