Reading Weeds as Soil Indicators: What Nature Is Trying to Tell You

For many gardeners, the appearance of weeds is the signal to reach for a hoe, pull them by hand, or spread another layer of mulch. While there is certainly a time for weed control, weeds can also serve another purpose. They are among the best soil inspectors you will ever have—and they work for free.

Long before soil laboratories and digital moisture meters, observant farmers learned to "read" the landscape. Certain weeds consistently appeared where particular soil conditions existed. While no weed provides an infallible diagnosis, a careful gardener can often learn a great deal about the health, fertility, drainage, and even the pH of the soil simply by observing what chooses to grow there.

Organic gardening is, above all, the art of observation. Instead of asking, "How do I kill this weed?" try asking, "Why is this weed growing here?"

Nature Rarely Leaves Bare Soil

Bare ground is an invitation. Wherever sunlight reaches exposed soil, nature sends pioneers to protect it. Weeds are often the first responders.

Their roots loosen compacted earth, hold soil against erosion, gather nutrients, and provide food for insects and microorganisms. While they may compete with our vegetables and flowers, they are also performing ecological work.

Rather than viewing weeds solely as enemies, think of them as indicators. They often reveal problems before our cultivated plants begin to suffer.

Plantain: The Compaction Specialist

Broadleaf plantain (Plantago major) frequently appears where soil has been compacted by foot traffic, machinery, or years of cultivation.

Its broad leaves hug the ground, and its tough taproot is remarkably good at penetrating dense soil.

If plantain thrives in your garden, consider asking:

• Has this area been walked on frequently?
• Does water puddle after rain?
• Would gentle loosening with a garden fork improve soil structure?
• Could additional organic matter help?

Removing the plant without addressing the compaction often results in another plantain taking its place.

Chickweed: A Sign of Rich, Moist Soil

Many gardeners regard it as a nuisance, yet its presence often suggests that the soil itself is in reasonably good condition.

Chickweed can indicate:

• abundant organic matter
• steady soil moisture
• cool conditions
• moderate fertility

Ironically, gardeners spend years improving poor soil only to discover that chickweed appreciates those improvements just as much as their lettuce does.

Purslane: Dry Soil with Good Fertility

Purslane (Portulaca oleracea) is a remarkable survivor.

Its succulent leaves store water, allowing it to flourish during hot summers when many weeds disappear.

Heavy populations may suggest:

• warm soil
• excellent sunlight
• periods of drought
• reasonably fertile ground

Interestingly, purslane is also edible and rich in omega-3 fatty acids. Many gardeners unknowingly pull one of the most nutritious wild greens from their gardens.

Horsetail: Poor Drainage and Acidic Conditions

If horsetail (Equisetum arvense) appears, pay attention.

This ancient plant has survived since before the dinosaurs and often points toward challenging soil conditions.

It commonly indicates:

• poor drainage
• compacted subsoil
• persistently wet ground
• acidic soil

Because horsetail spreads through extensive underground rhizomes, simply pulling it rarely solves the problem. Improving drainage often proves far more effective over time.

Dock: Deep Soil Miner

Dock species (Rumex spp.) produce impressive taproots capable of reaching nutrients far below the surface.

Their presence may suggest:

• compacted lower soil layers
• mineral imbalances
• neglected ground
• disturbed areas

The deep roots often bring nutrients upward, where they become available to other organisms after the leaves decompose.

Shepherd's Purse: Frequently Disturbed Soil

Shepherd's purse (Capsella bursa-pastoris) often thrives where soil is repeatedly disturbed.

Its appearance can indicate:

• freshly cultivated ground
• open soil
• winter annual weed cycles
• mild fertility

Because it completes its life cycle quickly, it often arrives before slower-growing plants become established.

Learn to Read Patterns, Not Individual Plants

One weed seldom tells the whole story.

A single plant may simply have arrived by chance. However, when large populations dominate a particular area year after year, they often reveal an underlying condition.

For example:

• Plantain and dandelions together may point toward compaction.
• Chickweed and nettles often suggest fertile, nitrogen-rich soil.
• Moss with horsetail frequently indicates excessive moisture.
• Purslane mixed with crabgrass may reveal hot, dry conditions.

The larger the pattern, the more reliable the diagnosis becomes.

Weeds Are Symptoms, Not Causes

One of the most valuable lessons in organic gardening is recognizing the difference between symptoms and causes.

Suppose your vegetable bed is full of plantain.

The temptation is to remove the weeds and declare victory.

But if the underlying problem is compacted soil, another generation of plantain—or a different weed adapted to the same conditions—will soon replace it.

Organic gardeners achieve longer-lasting success by correcting the conditions that favor troublesome weeds rather than merely eliminating the plants themselves.

Keep a Weed Journal

One surprisingly useful habit is to keep a notebook devoted to weeds.

Each season, record:

• which weeds appeared
• where they appeared
• rainfall
• mulching practices
• compost applications
• crop rotations
• drainage changes

After several years, patterns emerge that would otherwise go unnoticed.

You may discover that a certain weed only appears after unusually wet winters, or that another vanishes after several seasons of heavy mulching.

These observations become part of your growing knowledge of your own garden—knowledge no general gardening book can fully provide.

Let the Weeds Teach You

The goal of organic gardening is not to grow a garden without weeds. Such a thing has rarely existed.

Rather, it is to understand why weeds appear, manage them wisely, and gradually create conditions that favor the crops you wish to grow instead.

The next time you kneel to pull a weed, pause for a moment before tossing it into the compost pile. Consider what it may be telling you about the soil beneath your feet.

Nature is always speaking. The experienced gardener learns not only to cultivate the soil, but also to listen to it.

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Soil Tests – The Why and How

 

No doubt you've learned somewhere that soil tests provide essential guidelines for gardening. Perhaps the "why" and "how" have eluded you. This article might help.

You’ve probably noticed that different types of plants grow in different places. That’s because they are either native or adapted to distinct habitats. Drive through the countryside and you’ll see what I mean. On one side of a hill you might find a hardwood forest. The other side might be predominantly native pine. In another place there will be a grassy meadow. Farther along you might see a bog with sedges and alders. Each area has its own soil type, nutrient levels, drainage and chemistry. The lesson here is that plants thrive in locations and conditions that meet their needs.

Garden spaces are sometimes not so easy to judge. Further inspection and discovery will probably be necessary. Follow a similar exercise to your drive in the country when garden planning. Walk around your landscape taking note of drainage, sun exposure, slope and the plants that are thriving. Even moss and weeds can tell a story, but we'll delve into that some other time.

There are a couple of ways to determine your soil type, chemistry and condition. The first is to take a soil sample for testing. The second is to utilize the USDA Web Soil Survey tool. Taking a soil sample is easy enough. Using the USDA Web Soil Survey tool? Not so much.

A basic soil test will tell you three things: the soil pH (acidity or alkalinity), phosphorus (P), and potassium (K). Nitrogen (N) is not so easy to determine, so test results probably won’t show it. Advanced soil tests can reveal organic content and some minor element content. Keep in mind that a single soil test only provides a “snapshot” in time. Some of the element levels can change over the seasons.

Obtain a soil sample bag or bags from your local Cooperative Extension Service office. Fill in the blanks with your name, address and contact information. Check off the tests you want performed. Collect soil samples from various comparable places around your garden or landscape to provide a soil “profile.” Before taking samples, remove leaves and other debris from the immediate site. Scrape down to the actual soil. Mix the samples thoroughly in a clean plastic bucket. Transfer the mix to the soil sample bag, and return it to the office. A report should be mailed to you.

Using the USDA Web Soil Survey tool is another matter. You might find it here:

https://websoilsurvey.nrcs.usda.gov/app/

I can’t walk you through the steps. It wasn’t intuitive for me. You’ll just have to play around with the website until you figure it out for yourself. Nearly every square foot of the United States is included in the survey. No doubt you’ll find your square feet.

Here’s an example. Zeroing in to a delineated area on my property shows that it consists of two soil types: Pelham loamy sand (5.4% of the area) and Tifton loamy sand (94.6% of the area). What does that mean? According to the USDA, “The Pelham series consists of very deep, poorly drained, moderately permeable soils that formed in unconsolidated Coastal Plain sediments. These soils are on nearly level broad flats, toe slopes, depressions and drainageways.” “The Tifton series consists of very deep, well drained soils that formed in loamy marine sediments. Tifton soils are on interfluves. Slopes range from 0 to 8 percent.” Understanding these characteristics helps me figure out what to plant and where, especially if drainage is important.

With such facts in mind, the gardener can choose suitable crops and where to plant them. Obviously, this isn’t so vital if one is planting in containers or raised beds. However, when the homeowner is planning landscape plantings of trees, shrubs, perennials and vines, they are essential considerations.

You might have some particular plants in mind. If so, read the plant descriptions and learn about their soil requirements. Choose those that seem most compatible with your conditions.

If soil test reports indicate that amendments are necessary, make them weeks or months ahead of planting time to allow them to be incorporated into the soil and take effect.

It’s far easier to select plants appropriate to your situation than it is to dramatically change or amend your native soil to accommodate unsuitable plants of your choosing. Be realistic. Make it easy on yourself. Work with nature, not against it.

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4 Thinks You Should Know About Soil pH

Plant descriptions often include brief statements about the acceptable range of soil pH for those particular plants to thrive. So, there are four things you must know about soil pH. They are:

1. A low pH indicates an acidic environment,
2. A high pH indicates an alkaline environment,
3. pH of 7 is neutral, or right in the middle, and
4. You can take a sample to the nearest Cooperative Extension Office for lab analysis to find out the pH of your soil.

That’s all you really need to know. As with most things in life, a little basic knowledge is enough for us to function. If you’re satisfied now, please go to GoGardenNow.com, and check out my plants. If you’re curious and want to learn a little more, read on.

The meaning of p and H

Believe it or not, no one really knows for sure what “p” is supposed to mean! It depends on whose speculation you adopt. According to Wikipedia on pH (which is the obvious authoritative source for everything),

“The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. In the first papers, the notation had the "H" as a subscript to the lowercase "p", as so: pH.

The exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation, pH stands for "power of hydrogen". It has also been suggested that the "p" stands for the German Potenz (meaning "power"), others refer to French puissance (also meaning "power", based on the fact that the Carlsberg Laboratory was French-speaking). Another suggestion is that the "p" stands for the Latin terms pondus hydrogenii (quantity of hydrogen), potentia hydrogenii (capacity of hydrogen), or potential hydrogen. It is also suggested that Sørensen used the letters "p" and "q" (commonly paired letters in mathematics) simply to label the test solution (p) and the reference solution (q). Currently in chemistry, the p stands for "decimal cologarithm of", and is also used in the term pKa, used for acid dissociation constants.”

(If your eyes are now rolling back in your head, go to GoGardenNow.com and check out the plants. If not, read on.)

As noted before, H means “Hydrogen”. That’s easy enough to understand. So, “pH” refers to the concentration of hydrogen ions on soil particles. More particularly, it refers to the quantitative relationship between hydrogen ions and hydroxide ions. (I’m not going to explain the difference.) The accepted scale of measurement ranges from 0 to 14, with 7 being neutral. Solutions with more hydrogen are lower on the scale, so are acidic. Hydroxide solutions are higher on the scale, so are caustic or alkaline.

Why soil pH matters to plants

Soil pH matters to plants because it affects the availability of soil nutrients to their roots. Their roots can only absorb nutrients in certain ionic forms, and this can only occur within certain pH ranges. If the pH range is wrong, the nutrients are not made available to the plants. Most of the plants that we grow in our gardens require a soil that is more or less acidic. So, plant descriptions tell us what pH range is acceptable to that particular plant. Thankfully, the acceptable pH range is usually fairly wide. You will find, however, that if the pH range creeps up or down, the plant will begin to suffer and show signs of stress.

How pH changes

pH changes due to environmental factors. It can happen by itself, or you can make it happen. A soil scientist advised me a long time ago to test my soil the same time every year because seasonal changes can affect pH. Though the changes might be minor, differences will show on the soil test results and influence the recommendations.

If you need to make it happen, you won’t know unless you take a soil sample to your friendly local Cooperative Extension Service for analysis and recommendations. If you’ve never had your soil tested, start by doing it annually. Learn what changes result over time. If you see the pH stabilizing at a proper level year after year, take samples less frequently. If you observe signs of stress – chlorosis, for example – have your soil tested at once.

When you collect your soil sample, follow the instructions provided. One such instruction will direct you take soil from more than one place in your garden, and mix it up so you have a general soil profile. When you receive the results, follow the instructions. (I don’t know why I feel like I have to keep saying so.)

Now, if you’ve read this far, you should check out the plants at GoGardenNow.com. Be sure to observe the soil pH recommendations.