Murderous Plants? Save Your Garden From Sabotage

Wondering why your garden just isn't thriving? It could be being sabotaged...by other plants! Join Hank Green to improve your green thumb and learn which kinds of plants do NOT get along in a harmonious garden!

----------
----------
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:

Matt Curls, Alisa Sherbow, Dr. Melvin Sanicas, Harrison Mills, Adam Brainard, Chris Peters, charles george, Piya Shedden, Alex Hackman, Christopher R, Boucher, Jeffrey Mckishen, Ash, Silas Emrys, Eric Jensen, Kevin Bealer, Jason A Saslow, Tom Mosner, Tomás Lagos González, Jacob, Christoph Schwanke, Sam Lutfi, Bryan Cloer
----------
Looking for SciShow elsewhere on the internet?
#SciShow #science #education
----------
Sources:

These Plants Poison The Competition

[alexismandelias]

I like how the title went from the rather neutral "Plants that poison the competition" to the absolute news headline of a news article "Plants will absolutely murder each other"

[AnimeShinigami]

By contrast carrots boost tomato growth. Another common vegetable always stunts the growth of tomatoes near it, Kale. I've learned that one from personal experience. Two or three years in a row I had tomatoes refuse to grow when planted in the same bed/shrub pot as kale. Good to know that not everything bows to black walnut trees though.

[lisanorwoodtreefarm]

Just last night my dad showed me that a mature Norway spruce in his backyard had bent its own branch to shade out one of the new Norway spruces he had planted next to it. It looked like the branch was patting the smaller tree on the head, except the smaller tree was brown on top for lack of sun.

[LindaSchreiber]

An old gardener saying about generally putting a garden near a walnut tree is "a hundred yards or a hundred years". First, clearly distance, but the second is that even over decades, a big, old, walnut even years after it has died has invested the surrounding soil so thoroughly with juglone that its effects are still in play.

[janboreczek]

Black walnut (juglans nigra) is an american species, so Pliny couldn't have observed it. He was observing another walnut tree, a closely related english walnut, juglans regia (though it does not come from England, despite the name). Although the black walnut produces more of the juglone than english walnut, as far as I'm aware

[ScaerieTale]

When I was a kid my grandparents had a farm with two huge, old trees, one on either side of the property. One was an oak tree, but the other was a 40 or so year old black walnut tree. I always wondered why the entire area around that huge tree was practically barren!

[sarahbear]

The books Carrots Love Tomatoes is a great place to learn about what to plant together and what to plant far away. Companion planting is so good for home gardens!

[JanusKastin]

This kind of complex interaction between nature and agriculture is really fascinating at the same time it boggles my mind.

[ailivac]

The house I lived in as a kid had a large butternut tree (part of the walnut family) in the back yard. One of the few plants not affected by juglone is black raspberries, so the area around the tree was always completely full of raspberries and nothing else.

[pragati]

This was new to me. plant wars.
Also, Hank Green and the whole Scishow team is THE BEST! Keep up your good work!

[walkingmountain]

I lived in Montana and remember knapweed spreading like crazy. Whole pastures filled with it among what seemed like a desert for other plants.

[raphaelgarcia]

It’s also interesting to look at Eucalyptus and how unique the allopathic cocktail is to each individual.

[DanielleWhite]

I learned something new about sorghum. Decades ago I learned about its behavior of producing hydrocyanic acid if it wilts such as from frost damage, which was something we carefully had to watch as we had one year of adding Sudax (hybrid Sorghum and Sudan Grass, which also has the behavior) as a crop on my father's dairy farm in Pennsylvania.

[cupofkoa]

I'd recommend the book "Plant Partners". The author has done a lot of scientific research with a whole chapter on allelochemicals. As well as reducing chemical herbicides (to almost zero), it encourages the farmer/gardener to rethink plantation strategies. Chemical-drenched monocultures are literally the worst agricultural systems in history, and only exist because of the vast amount of money flowing in to prop them up.

[morewi]

Pliny was probably the first person to write about it. Just holding Walnut husks stains your skin brown, the husks are green. And it's a pain in the ass to clean.

[iwontliveinfear]

According to my available sources, Pliny The Elder died in 79AD, and the black walnut wasn't introduced to Europe until the Colombian exchange.
Pliny wrote about the Persian walnut (Juglans regia), not the black walnut (Juglans niger).

[adamseroka]

Dunno if you read the comments Hank. You're honestly one boss babe and I'm glad I stuck around all the way to the end. I study molecular plant sciences and really hadn't come across this concept during my studies. Like it, love it, want more of it.

[customizablebunny]

When growing up, a PSII issue also reduced my ability to thrive outside.

[tuwcouz]

My pet rabbit when I was 8 had musk thistle as its favorite treat lol

[Starphot]

Hickory trees do emit juglone, but not as much as grandma's black walnut trees. She moved into a brand new house and she planted two black walnut trees. The one bordering her driveway and next to her neighbor's property killed her neighbor's privet hedge. My neighbor's hickory tree is close to my property and my tomatoes and peppers take a hit when they are rotated there. The hickory is in soil with a pH of 8.0, alkaline, and that stress seems to up the dosage of juglone. Hickory likes a pH of 6 to 7, slightly acid. However hickory does grow here and they turn yellow and drop their leaves earlier than the other types of non-native trees here. Denver east of the North Platte was treeless plain. Onions, beans and garlic do well in the same spot. However, Summer Girl tomatoes seems to have a tolerance to juglone and early blight, a disease more common to gardeners today. The two extra plants near the hickory did as well as those in the main part of the garden this year until frost. The two other varieties wilted and died in July.