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How to Grow Giant Tomatoes
Written by: John Lyons - G.V.G.O.
Thank you to our fine friends from the Giant Vegetable Growers of Ontario (GVGO)for allowing us to republish this article.
There are many books written about growing giant tomatoes. I suggest you buy a couple and read up on the subject. Out of the many ideas you read about, you can make a plan for your own garden. Select a type of seed that produces giant tomatoes, Big Zack, Brandy Wine, Supersteak hybrid, etc. I am going to try a Heritage type called Purple Calabash this season, but there are many others to try.
The seed takes a bit of care to germinate. Soak the seeds for several hours in a mixture of water, with a 10% solution hydrogen peroxide (3%). This will kill off any funguses and revitalize the seed. I then place the seed on the damp paper towel in the cereal bowl, cover it with Saran wrap and put it up on top of the refrigerator. It seems to be warm enough to wake up the seed. Any warm area will do though. Once a trace of life appears, all seeds are set into pots containing damp, not wet sterilized potting soil and buried 1/8 of an inch deep into the soil. The pots are then set onto a heat tray @ (75-80 degrees) with clear plastic wrap over the top. This allows you to check on the seedlings progress. Once the seedling is up and two leaves appear, remove the plastic top. Spray it with no damp and keep the soil moist, but not wet. I set the pots under grow lamps, but a sunny window will do. It's OK if they become a little leggy.
While all this is going on, you will be out in the patch selecting a site for your giant tomatoes. Double dig a hole and mix compost, manure and peat moss. The moss is acidic and will help prevent fungus growth, since you are going to be watering more than usual. I also use 10-52-10 fertilizer to help promote good root growth once the plant is placed into its site.
If you start your seeds too early, the fruit will be ready too early. Most tomatoes only take 80 days or so to mature. So count back from your weigh off date 80 days or so and add a couple days for the cool September weather. If your weigh off date is the first week in October you should start them around the first of June. The tomatoes you plant for eating will be started around April 1. I start the seeds on the 1st, 15th, and the 30th of June. I stagger the dates to hopefully have my tomatoes ripe for the weigh off date. A ripe tomato only has a shelf life of two to three days so it's the real guessing game.
Naturally you'll harden off your plants before putting them into the garden. It's now time to set up a wind shelter. I build a windbreak out of 2"x 2" and cover it with plastic and set it up along the Windward side of the planting site. I also put in a 2"x2" post where each plant is to be set into the soil to help support the plant. Most if not all tomatoes are indeterminate and you will have to control them by pinching off excessive growth. Try to allow only two main vines to grow up along the post. I pinch off the lower leaves so nothing touches the soil. I also use an old 1 gal. coffee can with a hole in the bottom, set 1/2" inch into the ground at the base of the plant. Bugs than have a hard time accessing the plant with this around the base of the plant.
Water is the big deal now. You must keep the plant evenly moist, not wet. It took me three years to arrive at my best watering strategy. If you water too much the skin of the fruit cracks, if you water too little the plant actually withdraws fluid back out of the tomato itself, leaving you with blossom end rot on your fruit. On my soil (silt and clay mix) I apply 2 gallons of water per plant per week including rainfall. Three times a week if we get no rain. I mix a small amount of water-soluble fertilizer (20-20-20) in with the water every time I water the plants. This keeps the plant feed at an even pace. Once the plant begins to flower, I pinch off the first couple of clusters to keep the tomatoes off the ground. Examine the new clusters that come up after that for misshaped and double blossoms. Sometimes you find 2 flowers on one stem, these ones have good potential. Thin the remaining clusters of tomatoes to 2 or 3 and watch their progress. Eventually you will pinch off all the smaller tomatoes, and keep one tomato per cluster. You now have five or six tomatoes per plant. As time progresses you can cut them back until there is only one or two tomatoes per plant. These are the ones you hope will be the winning tomatoes. Pinch off the top of the plant. During this time of fruit selection, make sure you have been trimming the plant of excessive growth and spraying for insects and fungus. You should make sure that you leave enough foliage to shade your prize-winning tomato and provide a place for excessive water to go incase of accidental over watering. Keep your water and fertilizing program going right up to the weigh off date.
Once the weather cools its time to shelter the plant with a greenhouse. Mine is a 2"x 2" framed greenhouse with a plastic covering. It's constructed so I can dismantle it in the fall for easy storage over the winter. Make sure you can open it up on the warm days, since the temperature in easily reach 90- 100°, killing the plant and ending your hopes for this year. The greenhouse also keeps the plant warm during the cool fall days and keeps the cold rain off the plant. Water with warm water, but if you want to stop it from growing, water it with cold water and that will stop it from growing for approximately a week. The cold-water treatment might allow you to prolong the tomatoes life and allow it to the mature on schedule for the weigh off.
There is a lot the trial and error involved in growing giant tomatoes. Hopefully following these instructions will help you show up on weigh off day with a prize-winning tomato. Good luck, we look forward to your results at the weigh off.
Thank you again to our fine friends from the Giant Vegetable Growers of Ontario (GVGO) for allowing us to republish this wonderful article!