Potatoes are often linked to great tragedies and missteps - The potato blight of the 19th century, Vice President, Dan Qualye's on-camera misspelling of the word at an elementary school and now, the yellowing of the leaves of my potato plants.
Yellowing leaves can be the result of several different afflictions. I think my yellow leaves may be a result of too much water. We've had lots of soaking rain and humidity lately, and this may be the cause. If it's not, I may have bigger issues. Some of the possibilities include verticillium or fusarium wilt or psyliids.
Growing potatoes has been interesting - I've expanded my "crop" every year. I'm now in my third year of growing potatoes. My first year was pathetic. I may as well not have planted them. It was THAT bad. But, I tried again the next year and although I didn't get enough to feed an army, I got about 7 pounds of Red Pontiacs and Daisy Golds. The nice thing about potatoes is that they'll grow in anything - you could put a plastic bag or a trash can out there with some dirt and plant them, and they'd grow (unless you're me and off to a slow start). I use Smart Pots, which are aeration containers (I also have one large plastic container in use this year - I ran out of Smart Pots and still had potatoes to plant).
Growing Potatoes in Containers
To grow potatoes, start with tubers (aka "seed potatoes"). These are basically potatoes themselves that will sprout and start growing new potatoes. Some people just take potatoes they bought at the grocery store and put them in the ground. One word of caution about that - some growers spray potatoes with sprout inhibitors to try to keep them looking fresh for longer at the grocery store. This will prevent them or at least inhibit them from sprouting much if you plant them in your garden. You also may not know what else they sprayed them with. It's not that this can't work, but you should know where they came from and how they were treated before planting them in your own garden.
When you grow potatoes in containers, plant the tubers in a few inches of soil and compost, and put another few inches of soil on top. When the plants start showing stalks and leaves above the dirt line (see photo on the left below), start throwing a few more inches of soil in. Keep doing this over the next several weeks or so until you can't put any more dirt/compost in and you've about reached the top. They grow FAST. As you can see below, there's only 13 days that passed between the photo on the left and the photo on the right.
To help my yellowing potato plants along, I removed the yellowing stalks. I sprayed neem oil on the remaining plant leaves. I don't think I have a potato beetle/insect problem, but neem oil has helped on other plants with other issues like fungus/mold and I thought it couldn't hurt. Today, I added some compost to the top of the plants to provide some rich nutrients.
Hopefully, it's just a problem with too much water, but we'll see. I'm looking forward to some great fingerlings and Yukon Gold potatoes that I have planted. They've started flowering, but they'll stay in the ground a while longer. Wish me luck!