BER? More like GRRR!
Updated: Mar 2, 2020
I'm pretty sure that Blossom-end Rot (BER) shows up in every garden at least once a season, no matter how good the gardener. This year was the closest I've come to a no-BER season, but there it came as the temps finally climbed. GRRRR! It's usually easy to blame Mother Nature for the challenges that gardening presents, but we need to look at ourselves as at least partially to blame for this gardening calamity.
Blossom-end rot occurs in many vegetables but tomatoes seem to get the most press about it. No one wants to grow the proverbial $75 tomato so the onset of BER is as alarming as a plague of locusts! There goes Mother Nature again, sending locusts and BER and weather. Oh my! But I did say, we gardeners need to consider ourselves partly at fault for BER, right?
When something is wrong with ourselves or our plant babies, where do most people turn for solutions - Dr. Google, or Gardener Google in this case. Gardener Google is quick to point out that what caused this gut-wrenching and fruit-spoiling brown spot is a calcium deficiency, which has led to a proliferation of online quick-fixes like adding Tums or crushed egg shells to the soil.
If only gardening were ever that easy, am I right! Not enough calcium in the soil is almost never the problem. Watering is the problem. Yup. That's the part where it's on us as gardeners. Mother Nature can be blamed for the lack of rainfall and the high temperatures that cause the soil to dry out too quickly. We have to meet in the middle being ready to jump in and keep the soil appropriately watered as soon as the temps go higher and rainfall amounts go lower. Then we must be consistent. That's how to avoid BER. The only thing in the garden that needs Tums is the gardener - to help with the heartburn the onset of BER is likely to cause.
There are two things a gardener can do to prevent BER
Improve the soil structure
Why watering matters:
When talking to other gardeners, I find that comparing BER to the human body is really helpful. In both plants and humans, other chemicals are often needed to use a mineral. In humans, we need vitamin D to help use calcium. Coincidentally, plants need water to use calcium.
There is almost always enough calcium in soil, but just like a human body's ability to use the calcium is hindered by the absence of Vitamin D, a plant's roots can't use the calcium without water. When plants can't get the calcium they need from the soil, they pull it from the fruits (think bone loss in humans) and this is what causes the nasty brown spot on the bottom end of fruit - the blossom end. Ironically, BER has nothing to do with anything that happened to the blossom or pollination.
This is an over-simplified explanation, so I hope the scientists won't fault me for my lay-person summary, but it's a good bottom-line description for me.
How to water effectively:
The absolute most important thing is to water so that the soil stays damp several inches to a foot or more into the soil. In a container, the soil toward the bottom should never dry out. Effective watering can be done with just a hose but it's going to mean a lot of time dragging one around and in my case, made me more prone to underwatering and overwatering. I'd either put a hose somewhere and forget about it or get impatient and move on too soon. After a few seasons of that, most gardeners opt for drip irrigation like I did. I work full-time, so automating my drip irrigation system with a timer means I'm "working" in the garden even when I'm not there. Other gardeners who use drip irrigation will just turn on the water when the garden needs it. Either works fine. It's really preference.
Deep watering needs to start when the plants are young because it will encourage the roots to grow downwards. It's okay to let the soil surface dry a little because this signals to the plant that, instead of growing laterally in search of water, they need to go where the soil is damp... deeper. This will be a life-saver for the gardener and the plant when it matures. Mature plants need a lot of water, typically more water than is in the top inch or two of the surface of the soil. Plants are also mature when the season is hottest and driest, so the surface moisture is under double the pressure. The simplest thing to do in the long run, is water deeply so the plants aren't competing with evaporation for water at the surface.
For container gardeners: I grow in containers of varying sizes and material and it can be tricky to get the watering right. The container material will play a big role in how often you have to water because it affects how quickly water can evaporate. For example: a grow bag is going to dry faster than a plastic pot. Regardless of the plant, a bigger pot is always better because when there is more dirt, there is a lower likelihood that it will dry out before the next watering. Even with very large, 20-gallon plus containers, I typically need to water daily during the peak of summer.
Improving soil structure
Whether gardening in a container, raised bed or a grade-level (surface) bed, improving the quality of the soil will help reduce the likelihood of BER. This is done by adding compost. Making your own compost with kitchen scraps and available brown materials is the cheapest route. For anyone in suburbia like me, I recommend doing this in a compost tumbler, read my post about why here. Composted manures can be purchased, but some bagged varieties can contain topsoil which is often heavy in clay. This might be okay for those with sandy soil, but not great for anyone else. Both myself and other gardeners I trust have had the best luck with Black Kow bagged manure/compost. Bulk compost can often be purchased from local suppliers but it could be contaminated with who knows what, so it's best to purchase certified organic if it's available. This reduces the risk of unhealthy contaminates and herbicide carryover.
A few parting thoughts:
Antacids... It's the wrong kind of calcium anyway.
Not all calcium is the same. Even in humans, Tums aren't the most effective in dealing with a calcium deficiency because they're not the most easily absorbed. The same is true for plants. Antacids are Calcium Carbonate. Plants need calcium nitrate, calcium chloride, calcium chelates, lime (caution: significantly changes PH) or gypsum to supply calcium.
Egg shells will leave you waiting.
Egg shells have to break down, which in my experience can take a year or more, before the calcium is even absorbed into the soil.
But so-and-so said BER went away after using the antacid trick...
Here's why I think adding Tums or egg shells may seem to work. If I see something wrong with one of my plants, I immediately start paying more attention to it. When I'm paying better attention, plants are watered more regularly and I intervene if I realize the soil is drying out during the day. I address pest issues, take time to ensure damaged leaves are removed and give the plant any care that I've been neglecting, such as mulching. All of these things improve the health of the plant and prevent the moisture problems that lead to BER. In reality, the TLC healed the plant, not egg shells or antacids.