How to Grow Monstrosum Tomato

Wikimedia Commons

Monstrosum Tomato

Solanum lycopersicum 'Monstrosum'

vegetable

Monstrosum is an heirloom tomato variety prized for producing exceptionally large, deeply ridged fruits that can weigh 1-2 pounds each. The fruits have a complex, rich flavor with excellent sweetness and acidity balance. This indeterminate variety is a favorite among heirloom tomato enthusiasts for its dramatic appearance and outstanding taste.

When should you plant Monstrosum 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.

Get my Monstrosum Tomato timeline →

Example Monstrosum Tomato timeline · Pittsburgh, PA (Zone 6b)

Plant Monstrosum Tomato
Around Apr 17

Near Pittsburgh's average last spring frost.
Tend & protect
Late spring–summer

Watering, feeding, and pest-watch reminders.
Harvest Monstrosum Tomato
Around Jul 1

≈ 75 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Monstrosum Tomato dates for your own zip code.

Growing Conditions

☀️

Sun: Full sun, minimum 8 hours daily (10+ hours ideal)

💧

Water: Consistent, deep watering 1-2 inches per week; maintain even moisture to prevent splitting and blossom end rot. Water at soil level to avoid foliage diseases.

📏

Spacing: 24 inches

📅

Days to maturity: 75-85 days from transplant

🌱

Planting depth: 0.25 inches for seeds; plant transplants deeply (bury stems up to first true leaves)

Soil

Type: Well-draining, fertile loamy soil rich in organic matter

pH: 6.0-6.8

Amendments:

Compost aged manure bone meal potassium-rich fertilizer

Growing Zones

Find your zone →

Thrives in zones 5-10; grown as annual in cooler zones

3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a 10b 11a

Get my Monstrosum Tomato timeline →

Growth Stages

Seedling

2-3 weeks

Tiny plants with cotyledons and first true leaves appearing

Keep soil consistently moist but not waterlogged. Provide bright light 14-16 hours daily to prevent legginess. Maintain 70-75°F temperatures.

Vegetative

3-4 weeks

Plant develops multiple true leaves and strong stem growth; reaching 6-12 inches tall before transplanting

Harden off seedlings gradually before transplanting. Provide strong light to prevent stretching. Fertilize lightly with balanced fertilizer every 2 weeks.

Establishment

3-4 weeks

Transplants develop extensive root system and vigorous foliage growth in garden; plant reaches 12-24 inches

Install sturdy stakes or cages early (plant is indeterminate and grows tall). Pinch off lower suckers for air circulation. Water deeply and consistently.

Flowering & Fruiting

4-6 weeks

Yellow flower clusters appear along stem; small green fruits develop at first flower clusters; fruits enlarge and color develops

Maintain consistent watering to prevent blossom end rot and fruit cracking. Prune judiciously to improve fruit size. Feed with balanced or slightly phosphorus-rich fertilizer every 2-3 weeks.

Maturity & Harvest

4-8 weeks (extends until frost)

Fruits reach full size (1-2 pounds), develop characteristic deep ridges, color transitions from green to red; continuing production until frost

Harvest fully ripe fruits for best flavor. Continue watering consistently. Remove any diseased foliage. In late season, prune excess foliage to redirect energy to ripening fruits.

Companion Planting

Plan your garden →

Plant with:

basil carrot onion parsley marigold borage parsnip

Avoid planting near:

brassicas fennel potato cabbage kohlrabi

Common Pests

Hand-pick larvae; encourage parasitic wasps; use Bacillus thuringiensis (Bt) if infestation is severe
and (fungal diseases)
Choose disease-resistant varieties; practice crop rotation (3-year minimum); remove infected plants immediately; avoid overhead watering
Remove lower leaves; improve air circulation; apply copper fungicide preventatively; mulch to prevent soil splash
Increase humidity; spray with water; use neem oil or insecticidal soap; encourage natural predators
Use yellow sticky traps; spray with insecticidal soap; encourage beneficial insects; reflective mulch may deter

Uses

🍳

Fresh eating and slicing

Culinary

Monstrosum's large, deeply ridged fruits are perfect for slicing into thick steaks for sandwiches, salads, and plate presentations. The balanced sweetness and acidity make it ideal for fresh consumption without cooking. [source]

🍳

Sauce and preservation

Culinary

The meaty flesh and high solids content make Monstrosum suitable for fresh tomato sauce, salsa, and canning applications. One or two fruits can provide significant quantities for sauces. [source]

🏠

Exhibition and ornamental display

Household

The dramatic ridged appearance and impressive size make these tomatoes striking for farmers' market display, garden competitions, and home decorative arrangements. [source]

💊

Lycopene and antioxidant content

Medicinal

Like all tomatoes, Monstrosum contains lycopene, a carotenoid with potential antioxidant and anti-inflammatory properties that may support cardiovascular health. [source]

🍳

Flavor complexity and heirloom appreciation

Culinary

Monstrosum represents traditional tomato breeding focused on flavor over yield, offering complex, nuanced taste appreciated by culinary enthusiasts and gardeners seeking alternatives to commercial hybrid varieties. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Harvest when fruits are fully red and slightly soft to gentle pressure. Monstrosum tomatoes are best picked at peak ripeness and used within a few days. For the largest fruits, thin developing fruit clusters to 1-2 fruits per cluster. Can be picked slightly pink and ripened indoors if frost threatens. These large fruits are excellent for slicing and eating fresh rather than cooking whole.

Fun Facts

🌱 The name 'Monstrosum' literally means 'monstrous' in Latin, referring to the remarkably large and heavily ridged fruit size—some specimens can exceed 2 pounds.
🌱 Monstrosum is an indeterminate variety, meaning it continues growing and producing fruit throughout the season until frost, potentially reaching 6-8 feet in height with proper support.
🌱 This heirloom variety dates back to at least the 19th century and is preserved by seed-saving organizations worldwide, making it an important piece of agricultural heritage.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Full Sun Heirloom pH Sucker Transplant True Leaves

Shop Monstrosum Tomato plants and related plants at Plant Addicts →

Join 30,000 gardeners planning their gardens with LizPlants.

Get your personalized Monstrosum Tomato planting timeline

Tell us your zip code and we'll calculate exactly when to start Monstrosum 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 Monstrosum Tomato timeline →