How to Deal with Blossom End Rot – Treatment & Control

When it comes to pests and diseases, hydro growers have it easy. A customised nutrient regime means plants can fight off ailments with ease, and because there is nothing to attract them, pests are less likely to bother your crop to begin with. Unfortunately, blossom-end rot doesn’t discriminate, meaning hydro growers are at risk. Let’s talk about what blossom end rot is and what you can do about it…

It’s an experience most tomato growers will come to terms with. The excitement as your first young fruit sprouts is quickly followed by disappointment as it begins to discolour and rot from the bottom up.

The condition is blossom-end rot, and while we most commonly see it in tomatoes, it can also come for your capsicum, chilli, pumpkin, eggplant and cucumber.

Blossom-end rot generally rears its ugly head at the beginning of fruit formation.

To begin with, you may notice yellow-to-beige discolouration, which quickly expands and darkens in colour. In its early stages, blossom-end rot makes your crop feel watery and tender, especially in the affected areas. As the decay progresses, it grows tough, and the fruit underneath shrivels and wilts.

Now, we know that all sounds super scary, so we’ll hit you with some good news;

If you spot blossom-end rot on your crop, your plant has not fallen victim to infection, fungus or pest. While it may ruin your garden’s aesthetic, it won’t spread and can’t infect other plants.

The most common cause behind this frustrating problem is a calcium deficiency. The excellent news here is that once you sort out the deficiency, the affected plant will thrive and produce perfect fruit that same season.

It’s easy to play the blame game here, but whether you’re growing in soil or an inert medium, a calcium deficiency doesn’t always mean adding MORE calcium.

Plants need such a small amount of calcium that even the most infertile soil will generally have enough. Likewise, if you’re growing in Hydroponics, a one-part nutrient will have sufficient levels of calcium that you won’t need an additive.

Before you reach for that bottle of cal-mag, here are some other things that might cause blossom-end rot.

Over-watering your crop can dilute the calcium available to your plants. So whether you’re hand watering or live somewhere with frequent or heavy rainfall, if your crop is being over-watered, it may not be able to absorb calcium quickly enough to meet its needs.

Under-watering can also contribute as plants that are underwatered are more likely to be stressed, which can disrupt nutrient uptake across the board.

Highly acidic or basic pH readings are also a problem concerning plant deficiencies. Too high or too low of a reading, and you’ll lock up nutrients, making them inaccessible to plant roots.

Finally, and especially for hydroponic growers, confirm that you are looking at a deficiency, not toxicity.

Nitrogen is the biggest offender here, and the reason is two-fold.

Firstly, nitrogen supports fast, abundant leafy growth, which is great until it redirects nutrients like calcium from fruit to foliage, causing abnormal development.

Secondly, excess nitrogen transforms calcium into a salt-like state that plant roots cannot absorb, even when there are chemically high levels of calcium present through testing.

For more information about how to spot the differences between deficiency and toxicity, head to the link below.

Now, on to prevention and control.

Once you spot blossom-end rot, pick off all the rotting fruit so your plant can focus on the unblemished ones. The affected fruits you pick are harmless and can even be cleaned up and eaten. If you prefer to discard them, the compost pile is safe and recommended.

If you know your deficiency is not caused by one of the reasons listed above, you can apply a foliar calcium feed directly. Correcting the underlying cause will resolve the issue in most cases, and future tomatoes will be beautiful and unblemished.

Blossom end rot may have a dramatic appearance, but its bark is certainly bigger than its bite. Blossom end rot is not dangerous and is usually easy to treat. Providing your plants with the best growing conditions possible will mitigate the need for expensive and overcomplicated treatment regimes.

Hopefully, this newsletter helps your next harvest, and now when blossom end rot does make an unwanted appearance, you know the best way to send it packing quickly.

As always, thanks for tuning in to this month’s newsletter and until next time, happy growing!