The Trouble With Anecdotal Garden Tips (but it worked for me!)

Many garden tips are anecdotal, not science-based. Stay curious but lean on tested knowledge when you’re aiming for reliable results.

If this topic interests you, you will also enjoy Popular Garden Myths We’ve All Fallen For.

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The Problem With Anecdotal Garden Advice

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Many of us have seen—and probably shared—anecdotal garden tips, eager to try them in our own gardens.

Here are a few examples.

‘My grandmother always added crushed eggshells when planting tomatoes and it worked great.’

‘I water my African violets with milk and they bloom like crazy.’

‘My friend adds Epsom salt to her watering can and her vegetables are huge.’

And so on.

So what’s the issue? Why isn’t this considered solid evidence?

It all comes down to variables—all the possible factors that could have contributed to the plant’s success.

To be clear, questioning the role of eggshells in Grandma’s thriving tomato patch isn’t a slight against her or her garden. It’s simply recognizing that assuming the eggshells made the difference is a guess—not scientific proof.

Why? Because we haven’t ruled out all the other possible influences.

It may seem like the only change was adding milk, or Epsom salt, or eggshells—but gardens are dynamic, ever-changing environments. Conditions shift from day to day, season to season, and year to year. Countless factors influence plant growth, many of which we’re not even aware of.

That’s why anecdotes—personal stories or observations—aren’t strong evidence. They can be a starting point for investigation, but they aren’t conclusions. And just because two things happen together doesn’t mean one caused the other.

Luckily, we have science to help us make sense of it all. In some cases, research has already disproven popular tips. In others, we need proper testing—such as controlled A/B comparisons—to evaluate claims.

If you’ve spent time in gardening forums, you’ve likely seen how defensive people get when their anecdotal experiences are questioned. But this isn’t personal. It’s about understanding that anecdotes are just that—stories—not data. They could be onto something—or not.

Recognizing the difference between conjecture and evidence is key. If we truly want reliable, proven garden advice, we need to welcome healthy skepticism and be clear about what’s known, what’s guessed, and what still needs testing.

To explore this further, let’s take a closer look at those variables—and why they matter.

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Don’t Forget the Fundamentals

Let’s look at why variables matter so much.

For the sake of discussion, let’s assume the plant did thrive. We’re not doubting that success—just questioning what caused it.

The problem arises when we credit that success entirely to a specific action—like adding eggshells, watering with milk, or tossing Epsom salt into the watering can—without considering everything else at play.

Here’s the thing: while there’s always more to learn, science already knows the fundamentals of what plants need to grow. In nearly every case, success comes down to the basics:

• Light
• Water
• Air
• Temperature
• Nutrients
• And healthy, viable plants or seeds to start with

These are the key variables. When our plants thrive, these factors are in a good range. When plants struggle or fail, at least one of them is off.

Now let’s go back to that eggshells-and-tomatoes story.

Anecdotal advice assumes the eggshells were the game-changer. But we know plenty of gardeners grow excellent tomatoes without ever adding eggshells—so it’s clearly not essential.

At best, we’ve downgraded the tip to maybe it helped in one specific case.

Let’s say someone had poor tomato harvests for years, then tried planting with eggshells and finally got a good crop. That might seem like proof—but it’s not.

Why? Because we don’t know anything else about what changed.

Even in the same garden, conditions fluctuate constantly—light levels, rainfall, temperatures, soil composition, pest activity. Add in different tomato plants or seed varieties, and you have a completely different growing equation from one season to the next.

That’s why we can’t say the eggshells were the only change—or the reason for success.

To actually test the idea, we’d need to control for all the other variables and compare two identical groups: one with eggshells, one without. That’s how scientific research works. Only then can we begin to build real evidence.

Until then, it’s still a guess. A well-meaning one, perhaps—but a guess.

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Still curious about a garden tip? You can test it yourself with a basic A/B comparison. I do this for all sorts of things, like improving delphinium seed germination. It’s a great way to satisfy curiosity and gather more reliable observations.

And just to be clear—none of this means you need to stop using tips that seem helpful and do no harm. The point is to represent them honestly as anecdotes, and to keep an open mind when someone questions them.

That’s how we move toward better, more reliable gardening knowledge—together.

Using A/B Testing

If you’re curious to explore anecdotal garden tips more deeply, there’s a simple method you can try: A/B testing.

In short, the goal is to compare two sets of plants—one with the treatment (say, eggshells) and one without—under as identical conditions as possible. That way, if a difference appears, you have a better chance of linking it to the treatment and not some unrelated factor.

Let’s walk through an example.

Suppose you want to test whether adding eggshells improves tomato growth. First, decide how you’ll source and prepare the eggshells (washed? dried? crushed? pulverized?) and exactly how much you’ll use. Consistency is key.

Start with at least 10 tomato plants from the same seed packet or transplant tray. This helps eliminate variability in plant genetics and starting condition.

Next, aim to keep every other condition the same:

• Same type and amount of potting mix
• Same container size and material
• Same light exposure (duration and intensity)
• Same water source, amount, and temperature
• Same fertilizer (if any), applied on the same schedule
• Same planting time
• Same growing location (indoors or outdoors)

Yes, it’s nearly impossible to control everything perfectly—but the more consistent you are, the more reliable your results will be. Even subtle differences in sunlight or watering can influence growth, so do your best to equalize conditions across the board.

Once everything is set:

• Group A (five plants) gets plain potting mix.
• Group B (five plants) gets the exact amount of prepared eggshells mixed into the same potting mix.

Some gardeners go a step further and set up a “blind” test—where someone else labels the containers and the gardener doesn’t know which is which. This helps avoid unconscious bias in how each plant is treated.

While this is still “citizen science,” when done carefully, A/B testing can help reveal whether there’s any correlation between the added material and plant growth—or, more likely in the eggshell case, that there isn’t.

And the real test? When hundreds of other gardeners run similar experiments, under similar controlled conditions, and get the same result—again and again.

Until then? It’s just an anecdote.

Be a Good Skeptic

Whether it’s eggshells, milk, Epsom salt, or any other garden “remedy,” it’s always worth stepping back to consider the bigger picture.

The well-meaning gardener who swears by eggshells as a miracle cure might be overlooking something important: her success is likely rooted in the fundamentals—good light, healthy soil, consistent watering, and the right plant for the right place.

And that’s great! But giving credit to a single add-on—especially when it doesn’t align with what we know about plant biology—misses the real reason things are working—and leads other gardeners astray.

Take watering African violets with milk or adding Epsom salt to the soil. Each of these tips has its own story, but they can all be evaluated with a few basic questions:

• Based on what we know about plant needs, does this make sense?
• Are their growing conditions identical to mine—or wildly different?
• Could the plants be doing well despite the added ingredient, not because of it?
• Do plenty of other gardeners get good results without using it?
• Could this practice actually cause harm?
• Has it been studied? What does the science say?

We’re not trying to shut down curiosity or discovery—far from it. New ideas and better methods are always welcome. But when it comes to what we put in our soil and on our plants, it pays to stick to the basics, learn through experience, and stay open—but cautious.

Healthy skepticism isn’t negativity—it’s just careful thinking. And in gardening, that can be the most useful tool of all.

Resources

Strange Garden Tips

One of the most prolific garden personalities in recent decades was Jerry Baker, a TV personality and author. Through appearances and books, Baker spread hundreds and hundreds of absurd and potentially harmful garden tips. Many used household items like cooking oil, dish soaps, molasses, and ammonia that had no business in the garden. He also suggested hitting tree trunks was a way to stimulate growth. And, if that’s not enough, how about shampooing your lawn?

~Melissa the Empress of Dirt ♛