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The Plant Lady: Old wives’ tales persist, but you can beat them with a little knowledge

How to protect your plants from the cold

"Plant Lady" Marlene Simon, horticulturalist at UC Davis, explains how to cover your leafy plants and succulents in order to protect them from the cold. Dec. 13, 2018.
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"Plant Lady" Marlene Simon, horticulturalist at UC Davis, explains how to cover your leafy plants and succulents in order to protect them from the cold. Dec. 13, 2018.

We’ve all heard old wives’ tales about garden tricks. Here’s a classic:

“My Grandma used to bury pennies next to her roses and she had the best roses on the street.”

For the most part, they fall under coincidence. Sometimes there is loose science behind them but often they can harm plants. With the onslaught of online “experts,” it is difficult to filter out what is a truthful narrative. Here are a few of my biggest pet peeve myths.

Rocks in the bottom of pots

This myth has been the hardest to bust. The belief is that by adding gravel to the bottom of a pot, you are helping increase the rate of drainage. In reality, you are moving the area of highest soil water saturation (the soil at the soil/rock interface) up closer to the plant…possibly leading to rot. Additionally, you are decreasing the area for roots to grow. This is critical, as roots prefer growing in soil and will not grow well in rocks.

Soil acts like a sponge and will not release water until all air spaces are filled. At that point, gravity will take effect and the water will drain out of the pot. So either way — rocks or no rocks — the soil will saturate with water.

I have heard of some people using rocks because they are concerned about soil escaping through the drain hole at the bottom of the pot. There are options to prevent this, such as placing a piece of paper towel, coffee filter or even a curved piece of broken terra cotta pot over the hole.

Coffee grounds to acidify soil

Don’t throw your coffee grounds out just yet. The widely held myth is that they acidify soils. While this is not true, they are still beneficial. For the most part, plants prefer a pH range of 5.5 to 7.0. In some locales, acidifying soil is a must, due to high pH water or soil.

In this situation, adding coffee grounds to your soil seems like an easy solution. Here’s the caveat — used coffee grounds have a neutral pH. Coffee and fresh grounds are acidic, but not the grounds after they have had hot water through them. However, they do contain a trace amount of nitrogen, so there is justification to add them to your compost bins. Be cautious when adding directly to the top of your potted plants or soil. Microorganisms will use nitrogen in the soil to break down the coffee grounds. As such, you may see a quick decrease in nitrogen in your plants (yellowing), but this will be followed by a greening up as the grounds are broken down.

If you do need to acidify your soil, a far more efficacious solution is to add soil sulfur in spring/fall.

Bell peppers are male or female

This myth has been making the rounds on the internet. It states that based on the number of bumps on the underside of bell peppers, you can tell if a pepper is male or female, with the female supposedly being sweeter. Four bumps and it’s a female, three bumps it’s a male.

This is a simple one to demystify. There is no male or female fruit. The pepper is simply a swollen ovary that contains seeds. The difference in the number of lobes come from slight genetic variations, and sweetness can result from length of time the pepper has been on the plant, sun conditions and plant variety.

Calcium sprays for blossom end rot

Before we get to the myth, define blossom end rot. BER is a very distinct affliction on tomatoes (Romas are particularly susceptible), as well as other vegetables such as peppers and eggplants. On the blossom end side (the side opposite the stem; the “bottom” of the fruit), the tomato will turn solid brown to black. The rest of the tomato is unaffected and perfectly edible. It is true that this is caused by a lack of calcium but the soil deficit is almost always never the culprit.

Instead, it is the plant’s ability to utilize the calcium correctly. BER is usually seen early in the season when temperatures have not stabilized, so there seems to be a correlation between temperature, soil moisture and calcium utilization.

Now the actual myth: spraying the fruits or tomato leaves with calcium can combat BER. False. First, fruits cannot uptake calcium from their epidermis, as they have greatly reduced stomates (the opening on stems and leaves which allow gas exchange). When sprayed on the leaves, the calcium will be absorbed, however will not move into the fruit. Takeaway: It is a waste to buy the sprays. Instead, keep soil moisture levels even by adding mulch as soon as planted. Likewise, periods of drought will affect calcium absorptions, as well as soils which are distinctly anaerobic (no oxygen).

Avoid adding too much nitrogen, as nitrogen is the green-promoting nutrient. By encouraging more leaves, calcium will be drawn away from fruit and into the leaves, potentially stunting fruit formation altogether.

Usually, BER will correct itself after temperatures stabilize. If this affliction persists even with all proper practices in place, then a soil test for calcium may be required. If pH is below 5.5, adding lime will raise the pH, allowing calcium to be more available to the plant. If test shows calcium is lacking, then gypsum can be added.

Marlene can be reached my emailing: marlenetheplantlady@gmail.com. Follow her on Instagram@marlenetheplantlady and flowerpowergardenhour.libsyn.com.