Attack of the Giant Tomatoes: The Ultimate Growing Guide
Want to try growing the next world record tomato? Here’s what you need to know.
When Gordon Graham grew the current world record tomato—7.75 lbs.—in the summer of 1986 in Oklahoma, nobody could have known that this would become one of the longest running giant vegetable records.
The tomato is by far the most widely grown of the summer vegetables and it’s hard to fathom how this record has not been eclipsed. After all these years, indoor and outdoor growers alike are still striving to grow the world’s largest tomato, but after 26 seasons, no one has surpassed the mark Graham set.
When growing giant tomato types, high-quality seed selection is extremely important. Beef and super steak hybrid types are usually good choices. These seed lines, along with big zac, mega marv and delicious varieties, give a grower the best chance at a volleyball-sized fruit. A strong hopeful is the catapano, a controlled, self-pollinated giant seed line dating all the way back to 1998 from Toronto, Ontario. All of these seed types have the ability to grow 5-lb. or larger fruit from multiple fused blossoms.
The Tomato Seedling Stage
For outdoor growers, staggering the starting dates of plants is suggested to account for weather fluctuations and having a few tomatoes ripen late for a fall weigh-off date is important. It is possible to start seeds as early as six to eight weeks before last frost or as late as early June with a 90-day or more growth window. Normally, table-ready eating tomatoes would be started before April 1.
The seedlings may be briefly pre-soaked in a hydrogen peroxide solution to reduce fungal mold spores, bacteria or other disease issues. Afterwards they can be directly sown into small pots within a damp seed starting mix and left to germinate in a warm area.
The newly germinated plants are placed into a heated environment between 75 and 80ºF. Usually tomato seedlings are immediately placed under grow lamps, in a sunny greenhouse or close to a bright window. Legginess is reduced by increasing light intensities.
During this phase of growth, some growers will introduce far red light periods or reduce light to increase the internodes length. This may allow the grower to deeply bury the main stem horizontally or angle it to achieve additional root growth after transplanting the seedlings.
Transplanting Techniques for Tomato Plants
When it comes time to transplant, hardening off is required to lessen transplant shock. Sites need good drainage in place to ensure adequate soil aeration. Lengths of weeping tile can be set under the site to reduce soil saturation during irrigation or heavy rainfall to ensure the soil drains no matter how much water is applied.
Good drainage helps reduce soil-borne diseases and slows the buildup of the waxy suberin layers on older roots. Just like with other vegetables, it is healthy, adventitious roots that take up the nutrients, so the younger you can keep the plant and its root system, the more luck you will have.
The soil is generally a heavily treated and supplemented triple mix consisting of one-third each of peat moss, perlite and vermiculite mixed with a good amount of organic matter. Organic matter content approaching 7% or more will supply a happy rhizosphere. The soil’s pH is best at something slightly below 7, but this depends on your local soil mixture and conditions.
To deter insect pests, plants can be set in 10-gal. pots with several holes in the bottom to increase drainage. The side walls of the pot aid in moisture retention and slow encroaching pests like cut worms and nematodes. Set the pots deep into the main garden soil so that a half inch or so protrudes from the surface at the base of the plant. Some insect pests will have a harder time reaching the plant with a raised base around the vine stem.
Nutrients and Environmental Tips for Tomato Plants
The modern giant tomato grower will give his crop an assortment of biological supplements to assist with growth and development. These include bacillus subtilis, a root mass builder, and azospirillium, a nitrogen fixer.
Two fungi types—glomus intraradices (GI) and trichoderma harzianum (TH)—are often added to the soil. GI is a mycorrhizal fungi that enhances growth while the TH fungi helps protect the root zone from soil diseases.
Soil moisture and nutrient solutions with high solubility should be maintained at all times by either rainfall or irrigation, as even brief and relatively short moisture deficit periods can adversely affect the formation of fruit blossoms.
Growers may need to use cooling techniques if temperatures rise above optimal levels. Fans, misting and shade protection will help to relieve most harsh conditions. Other remedies include anti-transpirants like foliar sprays of absisic acid and CO2, as these help to close stomata and hold moisture within the plant and developing fruit.
Nutrient availability is key when growing giant tomatoes. High-quality irrigation water should provide maximum solubility of the macronutrients and micronutrients. Bi-carbonates in irrigation water often tie up micronutrients in the soil, making them unavailable to plants.
Humic acid and fulvic acids play a huge roll in raising a soil’s cation exchange capacity (CEC). They are both extremely porous and help act as chelators, holding onto nutrients and keeping them available to the roots.
Calcium is the driver, boron is the truck and humic and fulvic acids are the loading docks and factory. Building a vibrant and thriving root system with maximum uptake is the key. Soil can be supplemented with nutrients and acids and irrigated with pre-treated water to as low as 5.5 to ensure no tie-up issues in the soil.
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Pruning Practices for Large Tomatoes
The plants can be pruned in any of several patterns or grown along the ground for additional rooting. Commonly, the plant is allowed to grow upright with one or two main leaders. It is staked and then tied off every several inches or so.
All sucker growth is pinched off at the leaf node junctions. Growth can be reduced to a single main leader vine after the plant grows to 3 or 4 ft. in height. It is not necessary to set fruit on the first blossom truss. Be sure to trim off the lower leaves so that nothing touches the soil, as this reduces disease caused by irrigation splashing up from the soil onto the lower leaves. These giant types of tomatoes are indeterminate and growers must routinely remove new top shoot growth and leaf node suckers.
Tips and Tricks for Growing GIANT Tomatoes
Usually the largest tomatoes develop from fused super blossoms. These multiple fused blossoms are often located on the plant’s first flowering truss and are the first flower on the truss. Most plants will naturally produce a few super or fused blossom clusters on one or more trusses. If a fused blossom does not occur on the first truss, wait a few days for the next truss to develop.
Fused blossoms can be influenced somewhat by lower temperatures as the truss begins to emerge from the vine. A fused blossom consists of two or more conjoined flowers and gives the grower the best chance at growing a giant mater. Usually the best prospects will contain three to four or more flowers fused together to form a single, multi-segmented tomato.
Examine each fruit truss as it develops. Remember, size matters! The best giant tomato will come from the truss with the largest pedicle or stem heading into the fruit. Misshaped and double or more fused blossoms are your friend. Growers may begin to thin out the remaining trusses to the two or three biggest and largest.
Eventually, smaller tomatoes are pinched off after the primary has set. Keep one tomato only per truss. You will now have from one to three tomatoes per plant. At this time, the grower begins to select the largest and begins culling the smallest or slowest growers. Reducing the final selection of tomatoes to only one or two per plant increases size.
For giant maters, beauty and shape are really not that important. When growing the largest tomato, it’s only weight and size that matter. The final finished fruit will usually be multi segmented, pock marked, zippered or catfaced.
Zippering is a common trait in growing giant strains and is the result of an anther that eventually becomes part of the fruit’s external surface. It produces a zipper-like scar as the fruit grows, extending from the blossom end to the stem.
Catfacing is a tearing or splitting deformity that occurs during the formation of the flower at the blossom-end of the tomato. It can be caused by cold temperatures during flowering, or high nitrogen fertilization.
Direct sun is harmful to a developing fruit as it can hasten early maturity. Shading fruit and maintaining a consistent temperature is extremely important in delaying fruit senescence. Slowing ripening and extended the growth of cycle of the fruit itself to 40 days or longer results larger fruit.
Growth at the peak period can range from ½-in. to ¾-in. per day in circumference as measured from the widest length around the fruit’s equator. Measurements are taken daily to keep track of the growth rate and expected final finish of the fruit.
Ripe tomatoes only have a short shelf life and as soon as they begin to turn red, the weight and size gains generally halt. Then it’s time to have the tomato officially weighed, photographed, documented, witnessed and certified as a world record!
Written by Russ Landry | President
Russell Landry is the former vice-president of the Great Pumpkin Commonwealth and its many competitive weigh-off sites held worldwide. He is now the current president of the Giant Vegetable Growers of Ontario. Russ publishes the GVGO Growers’ Vine newsletter.