Growing Large Vegetables

Easy steps for growing giant sized vegetables

giant cabbage

The Spruce / K. Dave

Many gardeners enjoy the competition of growing the largest vegetables and flowers. Think 100-pound cabbages and pumpkins that gain 25 pounds in a day. These gargantuan veggies don't happen by accident; they take planning and care.

To compete seriously with the seasoned giant vegetable growers, you’ll need to put considerable effort into your soil, choice of site, and your gardening technique. But to get you started having some fun growing giant-sized vegetables, here are some easy steps toward success.

Choose the Right Seed

Serious giant growers will often seek out rare seeds to grow. You can start a giant lineage by selecting a promising variety, like Atlantic Giant Pumpkin or Old Colossus Heirloom Tomato, and then saving the seeds from your largest fruits for planting next year. (This only works with open-pollinated varieties, so steer clear of hybrids if you plan to save seeds.)

You may have to do some research on varieties that dependably grow into giants, but the name usually gives it away, like Russian Mammoth Sunflower, that grows upwards of 17 feet tall. Here are a few suggestions to get you started.

  • Cabbage: Northern Giant Cabbage (100 pounds)
  • Carrot: Japanese Imperial Long Carrot (12+ inches long)
  • Cucumber: Mammoth Zeppelin Cucumber (16 pounds)
  • Gourd: Giant Long Gourd (120 inches)
  • Onion: Kelsae Sweet Giant Onion (15 pounds)
  • Pepper: Super Heavyweight Hybrid Pepper (1/2 pound)
  • Pumpkin: Atlantic Giant Pumpkin (400 to 1000 pounds)
  • Squash: Show King Giant Green Squash (400+ pounds)
  • Sunflower: Grey Stripe Giant Sunflower (2-foot heads)
  • Tomato: Old Colossus Heirloom Tomato (2+ pounds)
  • Watermelon: Carolina Cross (Giant) Watermelon (200 pounds)
choosing seeds that will produce large vegetables

The Spruce / K. Dave


To beef up the soil, spread some manure or compost the fall prior to planting. If you’re serious about competing, consider having a complete soil test done and replenish any nutrients and micro-nutrients that are lacking.

Giant vegetables tend to grow in quick spurts, so they need lots of food. Slow acting organic fertilizers added at planting time will ensure that the food is there when the plant needs it. It will also make for healthier soil and fewer pest problems.

If you’re growing the plant for the fruit, like pumpkins and tomatoes, you’ll want a fertilizer that’s high in potassium and phosphorous, the last two numbers on the package. If you’re growing a leafy vegetable, like cabbage, you’ll want a higher nitrogen number.


Giant vegetables won’t be as tolerant of sporadic watering as the common garden vegetable would be, and even the common vegetable is touchy about not getting its one-inch per week. You have to provide regular deep watering, or your fruits will either languish or split. You can use drip irrigation on a timer that compensates for rain, so there are no slip-ups. While your plants need regular water, they will not prosper in extremely wet soil.

Thin to Just the Best Fruits

The more fruits on your plants, the smaller they will be. If they have to compete for nutrients, they’re never going to be giants. So prune or pinch out all but about three of the largest, healthiest looking fruits. Later in the season, you might want to thin down to just one, but keep a couple of extras at the beginning for insurance.

Don’t worry about too much foliage. The foliage is what will be feeding the fruits and helping them grow larger.

Keep a Close Watch

Pests and diseases can move in quickly and ruin an entire crop, especially when there are only a handful of fruits. Check your plants daily and correct any problems immediately. Try and remove troubled areas by hand, since using chemicals can disrupt the plant. Hopefully, since you’ve given your plants every advantage, problems will be few.

Now comes the hard part: You have to be patient. Look, but don’t touch. Too much fussing with your plants is as bad as too little. Give them the space they need to thrive and enjoy watching them grow.

pests on cabbage crop

The Spruce / K. Dave

Seek Mentorship

If you love growing giant vegetables, talk with the competitors at your local county fair. Some will be coy, but many are very open and generous with their knowledge. They’ll know who has the best seed and will be happy to discuss technique with you. There may even be a regional Giant Vegetable Growers organization in your area.

For a humorous, but very informative peek into growing giant pumpkins, check out the book "Backyard Giants: The Quest to Grow the Biggest Pumpkin Ever" by Susan Warren. The author follows competitors through an entire growing season and gives plenty of tips along the way.