Brian Moore with a row of giant sunflowers; the tallest sunflower is about 16 ft. The seeds came from a grower in the United Kingdom.
One of my three-year-old twin daughters standing in front of a row of corn and amaranth that’s more than 20 ft. tall.
Inspecting a self-sown sunflower growing on the edge of a patch of giant Jala maize (corn) from Mexico.
A mix of different English vegetable marrows. Marrows are very similar in taste to zucchini when cut under 12″. Marrows are not grown much in the U.S., but they’re common in the United Kingdom. Some varieties can grow to over 200 lbs.
Picture of Mercer County, N.J., Weights and Measures, measuring my 23 ft 2″ tall amaranth, which is listed in the 2009 Guinness Book of World Records as the world’s tallest amaranthus. More: Video of the amaranth being measured
Centaurea rothrockii is a hard-to-find biennial that produces enormous blooms on plants that are generally 4-5 ft., but I’ve had them over 7 ft.
Brian Moore likes big plants and he knows how to grow them. In 2007, his record-breaking amaranth grew to 23 ft. 2″. Want to grow your own giant plants? Here’s how Brian does it:
How tall are the sunflowers in your photos? Any record-setters?
Most of the sunflowers in my pictures are around 14 to 16 feet. The world record is a little over 25 feet; so there are no record-breakers. I had a world record for amaranth in 2007 at 23 ft. 2″, breaking the previous world record of 15 ft. 1″. The record is listed in the 2009 Guinness Book of World Records. My record was then broken by a 27 ft. 10″ plant from someone in I sent seeds to in upstate New York. Hopefully, I will get the record back this year. Last year, my tallest amaranth was 24 ft. 4″, so I’m getting closer.
What’s the key to getting extra-large plants?
No matter how great of a gardener you are, if your plants do not have the proper genetics then you will never get a large plant. When growing sunflowers I use varieties that I trade with other giant-vegetable growers. Those seeds usually produce the tallest plants. I then grow them and save the seeds to the best plants. Most sunflower varieities from commercial seed companies do not produce plants as large.
When growing tall corn, look for tropical varieties from Mexico, Columbia or Ecuador. When I first started growing corn, I used a type called Mexican June and it grew about 15 ft. on average. Now I grow a variety called Tehua, and this year it averaged about 25 ft.
What are some of the gardening techniques you use?
Proper spacing is one of the best ways to get plants tall. If you plant them too close, the plants will not reach their ultimate height. However, if you plant them too far apart, they don’t compete for sunlight. In the case of some plants, such as giant amaranth, they will bush out instead of growing up. I also find that controlled competition is good for my plants. I’ll plant a row of sunflowers and I will get various weeds and self-sown plants from my garden growing alongside the sunflowers. I let them compete to a degree, but as the sunflower gets taller and the root zone extends outward, I cut down or pull out the competitors. The competition for sun and resources speeds up growth so I can get more growth into a season.
Do you start seeds indoors?
The only time I start the sunflowers indoors is if I have a limited amount of seed and I want to guarantee to get a plant. Sunflowers do not transplant well. There are some seeds that I always start indoors. For instance, giant amaranth (Amaranthus australis) is much more sensitive to day length; so the longer the season the taller they grow. I start them in pots in January. I’ve been able to get those amaranth to 21 feet direct-sown (planting outdoors), but the season is too short to get them much taller.
What about staking and support?
Many of my sunflowers were grown without any stakes. If you do not stake your plants, be prepared to lose some of your crop by the end of the season. I think it makes the growing season rather exciting by not staking plants. It’s much more challenging to grow these plants without stakes. If I think a plant has a shot at a world record, I will get serious with staking. When I had my world-record amaranth I used a 21-ft. aluminum flagpole to secure the plant. When I grow plants along my house I use twine to tie them up from inside my second story window. I also find that if you just tie plants to one another, they all help keep one another up.
What’s your fertilizing routine?
I fertilize once or twice a day with small amounts of high-nitrogen, water-soluble fertilizer. However, the average gardener can still grow giants with little fertilizing. Every year I grow sunflowers at my wife’s parents house. I throw down some Espoma Garden-Tone when I turn the ground in the spring. With this approach, I’ve had them grow to almost 15 feet.
How does a person get started growing giant vegetables?
You have to do some research online. That means going on a search engine and type in “tallest sunflower” or “largest sunflower head”. There are communities of giant-vegetable growers on the internet. They usually deal with giant pumpkins, but those same people also grow other giants as well. Another good resource: your local county fair. Get to know some of the growers and try to get some seeds from them. Many growers are willing to help out someone new with some seeds and advice.