By Catherine Winter
I’m being cautiously optimistic: there’s a beautiful, round, perfect pie pumpkin developing beautifully in my patch, and I’m hopeful that it’ll actually ripen. Why am I being so cautious? Probably because I’ve lost literally every other pumpkin (and most of my squashes) to blossom end rot this year, so this wee beauty is a bit of a miracle.
When you’re growing food to feed your family, every failed plant represents at least one meal you won’t be able to feed them. With pumpkins and squashes, which can feed large numbers of people from each fruit, these kinds of losses can be devastating.
I wish I could have figured out what was wrong with my plants earlier in the season, as I could have treated them earlier, and had a bigger, better harvest. Fortunately, now that I know how to identify and treat blossom end rot, I can avoid losing any more plants to it in future.
…and even better, I can share this knowledge with you, in the hope that you don’t lose any time, effort, or beautiful heirloom plants to this issue either.
What is Blossom End Rot, Anyway?
Truth be told, I had never encountered blossom end rot before, so I had no idea what it was when I first saw it. I had been all excited to see the first pumpkins, squashes, and zucchinis form on their vines, but then that turned to disappointment when they all failed to thrive.
Blossom end rot appears as a sort of bruise-looking discolouration at the bottom of each fruit, and can appear on nightshade plants like tomatoes and eggplants as well as cucurbits like zukes, pumpkins, melons, and cucumbers.
Rather than being some kind of fungal blight—which is what I assumed it was at first—this rot is caused by calcium deficiency.
It usually happens when temperatures and moisture levels fluctuate dramatically. When this happens, the soil around the roots doesn’t remain consistently moist. As a result, the plants’ roots either don’t get enough water, or too much of it. Since they need a steady supply of calcium to create healthy blossoms, these fluctuations interfere with the plants’ abilities to draw in (and retain) the nutrients they need.
Poor blossom formation results in blooms that rot and die off before the healthy fruit can develop fully. This leaves an open wound at the bottom of the fruit, which will rot up all the way through it.
How to Prevent this issue
Blossom end rot generally first appears in the season’s first fruit set, if it’s going to appear at all. In addition to the aforementioned calcium deficiency, this rot can also occur if the soil was too cold and damp when the seeds are planted.
When planning your garden, make sure to do plenty of research as to the soil and sun requirements for that particular species/variety, as well as any special care it might need. Following grower’s guidelines will spare you a lot of heartache in the long run.
Work plenty of aged compost into the soil, as these plants are heavy feeders. Also add lime, bonemeal, and/or crushed oyster shells. These will provide extra calcium as they break down over the season. If you eat eggs, wash them out, dry them, crush them finely, and sprinkle the powder onto the soil whenever you can.
To prevent blossom end rot, plant seeds in the soil type that’s ideal for them, and keep moisture levels constant. This might require you to adhere to a really strict watering schedule to ensure the soil never dries out completely.
Additionally, you can work some extra vermiculite and/or peat moss into the soil for added moisture retention. Mulch can also work wonders to keep water (and by extension, calcium) in your soil. Just make sure to use a mulch that benefits the plant(s) in your garden, and won’t do them any damage.
When in doubt, speak to an employee at your local garden centre, or reach out to us for a consultation: our gardening team is always happy to help you out.
Related post: How Much Food to Grow Per Person
Treating Blossom End Rot
If you’ve dropped the ball, or the weather has just been too insane, you may have to contend with this rot affecting your plants. Don’t worry: it is treatable, and just takes a bit of extra time, effort, and a trip to the pharmacy. Get yourself a large container of TUMS or similar calcium-based antacid tablets, because you’ll need them.
No, not for your stress levels—for your garden.
To treat my pumpkins and zucchinis, I crushed up 10 TUMS tablets per plant, and dissolved them in about six cups of water. Once dissolved, I watered the soil around each plant thoroughly, waited 30 minutes, and then poured this calcium water around each root.
This provided an immediate calcium boost for each of my plants. Apparently, you can also pour whole milk into dampened soil to similar good effect!
After that, I removed any fruits that were showing signs of blossom end rot—which was basically all of them—and cut off any unhealthy leaves with a pair of clean garden snips.
Basically, I gave my plants a clean slate so they could start flowering and fruiting again from scratch, albeit later in the season than I would have liked.
Success!!
New blooms appeared almost overnight, and a week after watering, I poked four more TUMS tablets into the soil around the base of each plant. This way, they could dissolve slowly with each watering. I’ve repeated this process every week since.
Guess what?
Not only were the blossoms bigger and healthier than ever before, but the fruits that developed have been healthy. No more blossom end rot on my babies.
Granted, I might only get this one pretty pumpkin this year, but that’s okay. I’ve learned a valuable lesson, and as a gardener, I know that every season is an opportunity to learn more. Once mature, this Sugar Pie pumpkin will be large enough for several baked goods.
Even better, it will contain a good couple hundred seeds, which will allow me to grow many healthy, happy pumpkin plants next year, and have extra seeds available to share and trade.
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I am a first time farmer of pumpkins and watermelons and got so excited when the first fruits developed for both. Unfortunately the blossoms started rotting and falling off and I was wondering what went wrong. I have found your article very informative and educative. I am so grateful to you for sharing this experience. With this knowledge I hope to effectively manage bottom end rot in future. Please send me more articles on management of commercial vegetable farm. Txs a lot indeed.
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