Myths - Gardening is a book with seven seals

Garden Myths from A to pH

In gardening, it's a bit like cooking. Some swear by their grandmother's secret recipe, keeping it shrouded in mystery. Others boast of being the keepers of the holy grail – or should we say, the green thumb – and share their wisdom in a mentor-like tone. Such behavior often leads to many inconsistencies. In the following, we've decoded some of these myths, from A for "Abschreiben" to pH for "pH-Value."

Calcium Carbonate
If someone advises you to improve the soil with calcium carbonate, also known as lime, raise an eyebrow and leave it at that. The saying, "Lime enriches fathers but impoverishes sons," has its origins. Yes, liming has positive effects: it releases nutrients and improves soil structure. Unfortunately, this effect is short-lived. Even worse, the price you pay for it is outrageously high: you end up with a depleted soil with a high pH value, where plants will eventually wither. At best. By the way, the most lime is spread on lawns to get rid of unwanted moss, even though it rarely if ever works. Moss primarily thrives on compacted, shady, and poorly maintained lawns, not because the soil is too acidic. Just as an idea: why not appreciate such a mossy carpet?

Hot Composting

When you Google compost, it suggests that things can't help but get hot. According to this suggestion, proper composting involves chopping things small, stacking them all at once, turning them repeatedly (meaning turning the top to the bottom), covering it all, and – because it's covered – hand-watering it correctly. Only then does hot composting occur. If, in the best-case scenario, you've done everything right, the result is a nutrient-rich compost without unwanted seeds or disease-causing pathogens. The catch is this: you can also achieve great results by letting nature do the sweaty work, putting your feet up, and looking forward to the result. This is called cold composting. While not all seeds and potential pathogens are killed (which is not a problem if you don't give them to the compost heap), the end result is richer in beneficial microorganisms and fungi.

Juglone

Under walnut trees, you might be spared from mosquitoes, but unfortunately, nothing much grows there either. Additionally, walnut leaves take forever to decompose and make for poor mulch because they release inhibitory substances. Juglone is believed to be responsible for all of this. There is indeed such a growth-inhibiting substance. It's formed by the oxidation of hydrojuglone, produced in walnut trees. However, it doesn't effectively repel mosquitoes and only deters a few plants from growing nearby, if at all. The reason for this isn't due to the pH, but rather the fact that walnut trees have dense, extensive root systems. Hence, the soil beneath their shade-providing canopy is dry and relatively nutrient-poor. It shouldn't come as a surprise that tomatoes won't thrive there. As for walnut leaves, they decompose as easily as any other leaves. Moreover, the juglone contained in them completely breaks down within a short period – thanks to diligent microorganisms.

The fact that plants influence one another positively or negatively through the excretion of substances isn't a myth in itself. However, the effect is often significantly smaller than claimed or sometimes even entirely fabricated.

Bare Soil

One might think that this myth, given its distance from nature, would have become obsolete by now. However, the reality is quite different. There are still experts (at least they present themselves as such) who explicitly recommend keeping the soil between roses open and occasionally hoeing it. According to them, roses grow better without neighbors and mulch. And apparently, they prefer it without a healthy soil life as well.

pH-Value

If we were to award a gardening myth the top spot on the podium, it would be this one. No warning is more frequently and emphatically uttered than, "No! That will make the soil acidic!" It's astonishing how many things are said to lower the pH value: bark mulch, wood chips, sawdust (which are, however, excellent for deterring snails, unlike eggshells), coffee grounds, conifer needles, autumn leaves (such as those of walnut trees, precisely because of the juglone), and even grass clippings.

To put it briefly: it's nonsense. You can't artificially acidify the soil, at least not sustainably, and certainly not in an environmentally friendly way. If it were that easy, why would the soil need to be replaced when planting a simple rhododendron or a single blueberry, preferably with peat?

Conversely, the opposite is a breeze: to raise the pH value, you only need a certain amount of lime (calcium carbonate), and voilà! The soil becomes more alkaline. However, it's best to steer clear of that. There are very few things in the garden that can't be undone; liming is one of them. Just as an idea: you can embrace the existing pH of the soil and populate it with plants that love it just the way it is. That would not only be a lesson from nature but also a clever move... in the end, aren't they the same thing?

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