Evan X. Merz

musician / technologist / human being

Tagged "corn"

Sunflower allelopathy and learning from your mistakes

Since the COVID lockdown I've been spending more and more of my free time in my garden. It feels good to grow green things and the garden always has something to teach me.

I've realized that when you're working with living things, you never get it exactly right the first time. So whenever I try to grow something that I've never grown before, I always plan to fail. It's not that I intend to fail, it's just that I know how hard it is to succeed at growing something new the first time.

But setting expectations correctly doesn't mean that my failures don't surprise me and that they aren't great learning opportunities.

This year, I wanted to grow corn for the first time. So I read tutorials and watched youtube videos. I ordered high quality seed, and I thought I had a good idea what I was doing.

For instance, I learned that corn is wind pollinated. That means that the pollen actually has to fall down onto the silks, which will develop into the delicious ears of corn. For this to work properly, the corn has to be planted in a block, and that block has to be reasonably sized.

Since I'm gardening in the middle of the city, I had to carve out a new space for it. In the fall I dug out a section of my backyard and prepared the soil. In January I planted peas there so that they could do their nitrogen-fixing thing in preparation for the corn. I harvested the peas in May then I seeded the corn in dense rows.

I thought that maybe, just maybe, I could pull this off. Maybe I had grown enough as a gardener that I could actually get it right the first time.

Then the corn started coming up. Kind of.

It started emerging from the soil at the front of the bed, but not at the back, and I couldn't figure out why. I had watered evenly and deeply when seeding, then lightly for a week. Still the plants emerged slowly and unevenly.

In fact, they seemed to struggle more toward the back. Close to the sunflower.

A picture of a sunflower preventing the germination of corn plants.

I knew that sunflowers were allelopathic. Allelopathic plants use various strategies to prevent other plants from growing nearby. A fellow gardener had told me that sunflower seeds were allelopathic. That's why nothing grew under his birdfeeders. So as long as I didn't let the seeds fall, then I could plant sunflowers near other plants. Right?

Well, no. As it turns out, I misinterpreted what that gardener said. Yes, sunflower seeds are allelopathic, but so is all the rest of the sunflower. Every bit of the plant exudes chemicals that will prevent seeds from germinating properly or growing well. So the roots of my sunflower were digging into my corn bed and exuding chemicals that prevent my corn from developing normally.

And the worst thing is that it's too late to do much about it. I could dig out the sunflower before it flowers, till the soil, and heavily amend it. Then if I replanted the corn I might have moderately more success, but the allelopathic chemicals would still be there. And it's getting late in the season to start new corn. And that sunflower is 10 feet tall and still growing!

So, even with several years of gardening experience and learning, I managed to fail at growing corn the first time I tried it. I might harvest a semi-developed ear or two from my plot in a few months, but I won't get very much.

And that's a shame.

But at least I'll know better next year. I need to be very strategic about where I plant my sunflowers. Sunflowers seem to play nice with established plants, but they aren't so nice to young plants. I used to only plant sunflowers in my front yard, with established, decorative, native plants. I plan to return to that strategy.

As for corn, well, I'll try again next year. And this year I can go hard on the other two sisters. The squash and beans will have to make up for the failed sister!