📌 Saving Heat-Stressed Potatoes With Grass Mulch
- 🥵 The Heatwave Problem: When summer temperatures stay consistently high with no rain, potato vines turn yellow early, and the tubers stop growing entirely. You are left with a disappointing harvest of tiny “baby” potatoes.
- 🌧️ Will Late Rain Help? If the vines have already yellowed and died back, a late rain won’t restart tuber growth. Even if the vines are still green, water alone isn’t enough—potatoes need daytime temperatures to drop below 68°F (20°C) to actually bulk up.
- 🌾 The Grass Mulch Miracle: How do you save the harvest if you can’t control the heat? Check out Valeriy’s trick below! By packing thick layers of fresh grass clippings between the rows, he completely changed the soil microclimate.
- 👀 What You’ll Discover Below: Read the discussion to see how heavy grass mulch not only keeps the vines green during 95°F (35°C) droughts, but also creates natural compost and suppresses blight by generating beneficial soil bacteria (Hay Bacillus).
Marina111 wrote:
Luda, I keep hoping we’ll get a good rain and the potatoes will finally bulk up a bit. Or is it too late? They promise rain every day, but nothing falls.
Marina, I think it’s too late. If you planted a late-season variety and the vines are still strong and green, you technically have time, but just rain won’t be enough. The daytime temperatures need to drop down to about 68°F (20°C) for them to grow. And we are stuck in a heatwave again.
Everyone’s potato vines turned yellow a long time ago. We can start digging them up, but it’s just going to be tiny potatoes. I comfort myself with the thought that in the US, tiny “baby potatoes” are considered a great delicacy when roasted whole in the oven. Though usually, they use young, new potatoes for that!
Aleksan9ra wrote:
…I comfort myself with the thought that in the US, tiny “baby potatoes” are considered a great delicacy.
We are already digging ours up just to have something to eat. My girls are laughing, saying our garden is producing gold this year – we have so many gourmet baby potatoes! And the prices for them at the grocery store are definitely not pleasant.
Aleksan9ra wrote:
My neighbors have already dug up their potatoes, I should probably start too. The vines are completely gone. I dug up a couple of test hills, the potatoes aren’t amazing, but they aren’t tiny either, so that’s good!
Last year, July was incredibly hot and dry. The potatoes suffered terribly, and the harvest was awful. So this year, I wasn’t lazy—I mowed a bunch of grass and packed it thickly between the potato rows. Good for me! We’ve had a severe heatwave and drought from May 9th to this very day, and they are predicting another week of 95°F (35°C) heat.
My potato vines are drying out a bit, of course, but they are STILL green. I also discovered two other huge benefits of covering the rows with grass mulch: first, it breeds Hay Bacillus (a beneficial bacteria), which completely prevents Late Blight. Second, the grass rots and is processed by microorganisms and earthworms, creating free fertilizer right in the bed.
Here is a photo from June 27th:
Valtwelve wrote:
My potato vines are drying out a bit, of course, but they are STILL green.
Yes, yes, yes! Grass mulch on potatoes is an incredible thing. The potatoes growing under the mulch are still completely green, even though the vines are so heavy they are laying on the ground. But the rows where I didn’t have enough mulch have already completely yellowed and died back.
