Reading the Weeds: What Weeds Can Tell You About Your Garden

They can be clues to soil fertility, moisture, compaction, and more.

hand holding a fistful of green weeds pulled out from garden with roots

Treehugger / Nadia Hassani

Weeds are often considered to be the bane of every gardener's life. Some look at them as the "enemy" and do all they can to get rid of them entirely. But sometimes weeds are simply plants ideally adapted to the situation in a given garden.

With the exception of invasive, non-native species, which should usually be eradicated for the health of the native ecosystem, many weeds can be useful to have around. A number of common weeds have a range of uses. They can be edible, medicinal, or provide benefits within the garden through wildlife attraction.

But what new gardeners do not realize is that weeds can tell us a lot about the soil in our gardens and its characteristics. Reading the weeds—thinking about the conditions they like best and where and how strongly they are growing within your space—can reveal things to you about your garden and what other plants may thrive there. While weeds will not tell you everything you need to know, they are one factor that can help you make garden choices.

Weeds May Tell You About Fertility

stinging nettle is a green weed with serrated leaf edges that grows in gardens

Treehugger / Nadia Hassani

In certain parts of my garden, stinging nettles are one of the most prevalent "weeds." Stinging nettles grow in many different conditions; but where they grow particularly well can be a good sign of garden fertility, since they thrive in fertile, nitrogen-rich soil. Lambs'-quarters, henbit, and chickweed are other useful herbs that I welcome in my garden, and these also tend to indicate a rich and fertile soil where they are growing strongly.

Rose-bay willow herb, or fireweed, grows in areas of disturbed ground which are fertile and thrive where the soil is rich in potash. They like moist yet free-draining conditions, though they are pioneers which can quickly colonize many sites.

Weeds May Tell You About Soil Moisture

various green weeds grow along concrete sidewalk

Treehugger / Nadia Hassani

In wilder fringes around my garden, soil moisture is one of the key characteristics that determines which weeds do best. I can tell which areas are prone to wetter and boggier conditions due to the presence of dock and germander speedwell and creeping buttercup. Horsetail and goldenrod may be indicators of damper or wetland conditions elsewhere. Common hogweed, a common weed in my area, likes moist areas. In drier, less managed parts of my garden, cow parsley proliferates in the dry, dappled shade of garden fringes beneath some woodland trees. 

Weeds May Tell You About Compaction

yellow dandelion flower weed grows outside in garden

Treehugger / Nadia Hassani

In a trafficked, gravel yard area on my property, dandelions and plantain (Plantago major) proliferate. These tend to indicate quite poor and compacted soil. Though not something I tend to encounter on my own property, bindweed can also signify a crusted soil which suffers from some compaction. 

Weeds May Tell You About Soil pH

garden trowel stuck in dirt near rosemary growing in outside garden

Treehugger / Nadia Hassani

Docks and horsetails, for example, can be an indication that soil is acidic (though I have a broadly neutral to mildly alkaline soil and so this is not necessarily the case). Weeds can sometimes provide an indication about soil pH, though, as with the other categories, weeds often overlap between categories and thrive in different soil conditions. This is a reminder that, while reading the weeds can be helpful, they cannot tell us everything we need to know. 

Understanding weeds is important in creating and maintaining an organic garden. They can help you determine what else to plant where, and can help you make other decisions about how you use and manage your space. And remember, weeds deserve respect; they are very successful plants and many can be useful additions. I always leave some space for native "weeds" in my garden.

Understanding our gardens better should always be a key goal in a sustainable, eco-friendly organic garden. Observation is key, and by learning more about our gardens over time, we can learn to work with nature and to manage our gardens in the right way.