How to Grow Giant Colossal Tomato
Wikimedia Commons
Giant Colossal Tomato
Solanum lycopersicum 'Giant Colossal'
vegetableGiant Colossal is an indeterminate heirloom tomato variety known for producing extremely large, meaty fruits that can weigh 1-2 pounds or more. The tomatoes have deep red color, rich flavor, and relatively few seeds, making them excellent for slicing and fresh eating. This vigorous grower requires substantial space and sturdy support structures.
When should you plant Giant Colossal Tomato in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Giant Colossal Tomato timeline · Pittsburgh, PA (Zone 6b)
-
Plant Giant Colossal Tomato
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
Harvest Giant Colossal Tomato
Around Jul 1≈ 75 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Giant Colossal Tomato dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 5-9; can be grown in zones 3-4 with season extension and zone 10+ in winter growing areas
Sign up free to see if Giant Colossal Tomato grows in your zone — and get a personalized planting timeline.
Get my Giant Colossal Tomato timeline →Growth Stages
Seedling
2-3 weeksSmall plants with 2-4 true leaves, approximately 2-3 inches tall. Cotyledons (seed leaves) present with true leaves emerging.
Keep soil consistently moist but not waterlogged. Provide 14-16 hours of bright light daily. Maintain temperature of 65-75°F. Thin seedlings to prevent crowding and ensure sturdy growth.
Vegetative
3-4 weeksRapid growth with establishment of main stem and lateral branches. Plant reaches 12-24 inches with multiple sets of true leaves. Root system developing extensively.
Harden off transplants gradually before moving outdoors. Plant outside after last frost date when soil is 60°F+. Install sturdy cages or stakes immediately upon planting. Prune bottom 6-8 inches of foliage once plants are established to improve air circulation.
Flowering
3-4 weeksFlowers appear in clusters (trusses) along the main stem and branches. Yellow flowers are typically 3/4 inch across. Plant continues vertical growth and becomes bushy with dense foliage.
Maintain consistent watering schedule; fluctuations cause flower drop and fruit cracking. Ensure adequate calcium intake (add crushed eggshells or lime if needed) to prevent blossom end rot. Continue pruning lower foliage and remove lower suckers on indeterminate varieties.
Fruiting
4-6 weeksYoung green fruits develop and swell rapidly at flower sites. Fruits can reach 2+ pounds as they mature. Plant becomes heavily laden with foliage and developing fruit clusters. Color gradually changes from green to deep red.
Prune aggressively to limit fruit load if desired for larger individual fruits—remove every other flower cluster for giant specimens. Provide robust support as fruit weight will be substantial. Water consistently (1.5-2 inches per week). Mulch heavily to regulate soil moisture and temperature.
Harvest
6-10 weeks (continues until first frost)Fruits reach full size and deep red color, typically 1.5-2+ pounds each. Skin becomes slightly softer with slight give when gently squeezed. Continue producing new flowers and fruits as indeterminate variety.
Harvest fruits when fully colored and slightly soft to the touch. Pick in early morning for best flavor. In cooler climates, harvest green-mature fruits at frost threat and ripen indoors. Continue feeding and watering to extend harvest season through fall.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
Hand-pick larvae; encourage parasitic wasps; use Bt (Bacillus thuringiensis) spray if infestation is heavy
-
Use yellow sticky traps; spray with insecticidal soap or neem oil; encourage natural predators like ladybugs
-
Remove affected lower leaves; improve air circulation; apply copper fungicide; avoid overhead watering
-
Remove infected plant material; apply fungicide containing chlorothalonil or copper; ensure good drainage and air flow
-
Spray with water to dislodge; use miticide if severe; maintain consistent humidity
-
Spray with water; use insecticidal soap; release ladybugs or parasitic wasps
Uses
Premium Slicing & Fresh Use
CulinaryGiant Colossal's large size, meaty texture, and few seeds make it ideal for slicing thick tomato steaks for sandwiches, burgers, and salads. The rich, complex flavor is superior in fresh applications where the tomato is the star ingredient. [source]
Sauce & Preserve Production
CulinaryThe high flesh-to-seed ratio and rich flavor make these tomatoes excellent for making tomato sauce, paste, and other cooked preparations. One or two fruits can yield substantial sauce quantities. [source]
Home Preservation
HouseholdLarge fruits are ideal for canning, freezing, or drying due to their size and meaty structure. Their low seed and juice content relative to flesh makes them excellent for canned tomato products. [source]
Seed Saving
CraftGiant Colossal is an heirloom open-pollinated variety, making it ideal for seed saving. Seeds can be fermented and dried for replanting the following season, reducing future gardening costs. [source]
Pollinator Garden Support
WildlifeTomato flowers attract bees and other pollinators. Growing Giant Colossal along with companion plants creates a productive garden ecosystem that supports beneficial insects. [source]
Harvest Tips
Harvest when fruits are fully colored deep red and yield slightly to gentle pressure. Giant Colossal fruits are ready to pick when individual tomatoes reach 1.5-2+ pounds. Pick in early morning for peak flavor and juice content. In cooler zones, pick green-mature fruits (fully sized but not yet colored) before the first frost and ripen indoors at room temperature (70°F) for 1-2 weeks. Handle large fruits carefully to avoid bruising. Continue harvesting regularly to encourage production.
Fun Facts
- 🌱 Giant Colossal is an heirloom variety that has been passed down through generations; true seeds can be saved and replanted indefinitely to maintain the exact variety
- 🌱 A single mature Giant Colossal fruit can weigh as much as a small cantaloupe—sometimes reaching 2 pounds or more—and a single plant can produce 15-30+ fruits in a season
- 🌱 This variety is indeterminate, meaning it grows continuously and keeps producing new flowers and fruit until frost kills the plant, potentially providing tomatoes from mid-summer through October in many climates
Gardening Terms
New to gardening? Learn about terms used in this guide:
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Giant Colossal Tomato planting timeline
Tell us your zip code and we'll calculate exactly when to start Giant Colossal Tomato seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Giant Colossal Tomato timeline →