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How to Grow Waterloo Tomato

Waterloo Tomato

Solanum lycopersicum 'Waterloo'

vegetable

Waterloo is a determinate (bush) tomato variety known for its disease resistance and reliable production of medium-sized red fruits. It was developed in Canada and is particularly valued for its resistance to late blight, a devastating fungal disease. The plants are compact and manageable, making them suitable for both garden beds and container growing.

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

  1. Plant Waterloo Tomato

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Waterloo Tomato

    Around Jun 21

    ≈ 65 days after planting

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

Growing Conditions

☀️
Sun: Full sun, 6-8 hours daily minimum; 8+ hours preferred for best fruiting
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Water: Consistent moisture; water deeply 1-2 inches per week. Avoid wetting foliage to reduce disease risk. Water at soil level, especially important given this variety's disease susceptibility.
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Spacing: 24-36 inches
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Days to maturity: 65-80 days from transplant to first ripe fruit
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Planting depth: Start seeds 1/4 inch deep indoors 6-8 weeks before last frost; transplant at 2-3 true leaves; plant transplants deep (bury stem up to first true leaves)

Soil

Type: Well-draining loamy soil rich in organic matter
pH: 6.0-6.8
Amendments:
Compost aged manure peat moss or coconut coir balanced fertilizer (5-10-10)

Growing Zones

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Thrives in zones 3-9; excellent for cool and short-season climates

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

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Growth Stages

1

Seedling

3-4 weeks

Small plants with 2-4 true leaves emerging; delicate stems and initial leaf formation

Provide bright light (14-16 hours daily under grow lights), keep soil consistently moist but not waterlogged, maintain 70-75°F, and thin or transplant to prevent crowding

2

Vegetative Growth

3-4 weeks after transplanting

Stocky transplants 6-8 inches tall with 6-8 true leaves; sturdy stems developing

Harden off seedlings over 7-10 days before transplanting outdoors; transplant after last frost date; space 24-36 inches apart; pinch suckers on determinate plants only if they interfere with air flow

3

Flowering

3-4 weeks

Yellow flower clusters appear on determinate growth pattern; plant reaches mature height of 3-4 feet

Maintain consistent watering to prevent blossom end rot; provide balanced fertilizer or switch to lower nitrogen (phosphorus-rich); ensure good air circulation; watch for early blight on lower leaves

4

Fruiting

3-4 weeks

Medium-sized round fruits develop and begin to mature; fruits transition from green to light red to deep red

Continue consistent watering; remove any diseased lower leaves; support heavy fruit clusters with cages or stakes; thin fruit if necessary for larger size; monitor for pests and diseases closely

5

Harvest

4-6 weeks until frost

Fully ripe red fruits ready for picking; production continues until first frost

Pick fruits when fully colored and slightly soft; harvest ripe fruits regularly to encourage continued production; late blight may affect plants in damp conditions, so remove affected fruits immediately

Companion Planting

Plan your garden →

Plant with:

basil carrot parsley onion garlic borage marigold nasturtium

Avoid planting near:

brassicas (cabbage, broccoli) fennel kohlrabi potatoes dill

Common Pests

  • Hand-pick larvae and eggs; encourage parasitic wasps; use Bacillus thuringiensis (Bt) if infestation is severe

  • Spray neem oil or insecticidal soap; use yellow sticky traps; encourage beneficial insects

  • Spray with water to dislodge; use insecticidal soap; introduce ladybugs or lacewings

  • Increase humidity; spray with water; apply neem oil; encourage predatory mites

  • This variety has late blight resistance. Remove affected leaves immediately; improve air circulation; avoid overhead watering; apply copper fungicide if needed; mulch to prevent soil splash

Uses

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Fresh eating and slicing

Culinary

Waterloo tomatoes are medium-sized, well-shaped fruits ideal for slicing fresh into salads, sandwiches, and other fresh dishes. Their balanced flavor makes them suitable for everyday culinary use. [source]

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Sauces and cooking

Culinary

These tomatoes can be cooked down into sauces, salsas, and other cooked preparations. Their determinate nature means a concentrated harvest makes them practical for processing. [source]

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Nutritional and antioxidant benefits

Medicinal

Waterloo tomatoes contain lycopene and other antioxidants associated with health benefits including cardiovascular health support. Fresh tomatoes provide vitamin C and potassium. [source]

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Disease-resistant variety for home gardeners

Household

Developed for late blight resistance, Waterloo is an excellent choice for gardeners in humid or cool climates who struggle with fungal diseases. Its reliability makes it ideal for beginning and experienced gardeners alike. [source]

🦋

Supporting pollinators

Wildlife

Tomato flowers attract bees and other pollinators to the garden, supporting broader ecosystem health and biodiversity. [source]

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

Harvest Tips

Pick fruits when they reach full color (deep red) and are slightly soft to the touch. Waterloo fruits typically measure 3-4 inches across. Harvest ripe tomatoes regularly to encourage continued flowering and production. For the best flavor, allow tomatoes to ripen fully on the vine. If frost threatens, harvest remaining green fruits and ripen indoors in a paper bag or window. Determinate varieties produce most of their crop within 2-3 weeks of the first harvest.

Fun Facts

  • 🌱 Waterloo was developed by Agriculture and Agri-Food Canada and is named after the city of Waterloo, Ontario. It was specifically bred for Canadian growing conditions and late blight resistance.
  • 🌱 This variety is particularly valued by gardeners in cool climates and short seasons because it matures relatively quickly and produces a concentrated harvest typical of determinate tomatoes.
  • 🌱 Waterloo's resistance to late blight (Phytophthora infestans) makes it an important variety for sustainable gardening, as this disease caused the Irish potato famine and remains a major challenge for tomato growers worldwide.

Gardening Terms

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

Full Sun Last Frost Date pH Sucker Transplant True Leaves
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