How to Grow Magnum Bonum
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Magnum Bonum
Solanum tuberosum 'Magnum Bonum'
vegetableMagnum Bonum is a heritage potato variety known for its large, oval tubers with pale yellow flesh and thin skin. It is a maincrop potato that stores exceptionally well and produces high yields. This heirloom cultivar has been grown since the 19th century and is prized for its versatility in the kitchen.
When should you plant Magnum Bonum in your zone?
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Example Magnum Bonum timeline · Pittsburgh, PA (Zone 6b)
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Plant Magnum Bonum
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Magnum Bonum
Around Aug 5≈ 110 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Magnum Bonum dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-8, with best performance in cooler climates
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Seed Piece & Sprouting
2-3 weeksSeed potatoes develop sprouts (eyes) and begin root formation in cool soil.
Plant whole seed pieces or cut pieces with at least 2 eyes each. Ensure soil temperature is 45°F or above. Keep soil moisture consistent to prevent rot.
Emergence & Early Growth
3-4 weeksShoots emerge through soil and develop first true leaves. Plants establish root systems.
Hill soil around emerging shoots to prevent greening of tubers. Monitor for pests like Colorado potato beetles. Maintain consistent watering.
Vegetative Development
4-6 weeksPlants grow vigorously with dense foliage. Extensive root system develops underground.
Continue hilling soil as plants grow. Fertilize with balanced fertilizer or compost. Watch for pest damage and disease symptoms. Hill 2-3 times total.
Flowering & Tuber Development
4-5 weeksPlants produce small white or purple flowers. Tubers rapidly enlarge underground as energy shifts from foliage.
Maintain consistent water supply—critical for large tuber development. Reduce nitrogen fertilizer to avoid excess foliage. Continue pest monitoring.
Maturity & Harvest
2-3 weeks before harvestFoliage begins to yellow and die back. Tubers reach full size with set skin.
Stop watering 2 weeks before harvest to allow skin to harden. Harvest when foliage is mostly dead. Handle tubers gently to avoid bruising. Cure in cool, dark place for storage.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick beetles and egg clusters. Use row covers on young plants. Apply neem oil or spinosad. Rotate crops annually.
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Spray with insecticidal soap or neem oil. Encourage beneficial insects. Use reflective mulches.
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Practice crop rotation. Till soil deeply. Trap with potato pieces buried in soil. Use beneficial nematodes.
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Plant certified disease-free seed. Ensure good air circulation. Remove infected foliage. Apply copper or sulfur fungicides preventively in humid conditions.
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Remove lower leaves as plants grow. Mulch to prevent soil splash. Apply fungicides if needed. Practice crop rotation.
Uses
Roasting & Baking
CulinaryLarge oval tubers of Magnum Bonum are ideal for baking whole or cutting into large wedges for roasting. The firm texture and mild flavor make them excellent for crispy roasted potatoes. [source]
Mashing & Puree
CulinaryThe yellow flesh and waxy texture make Magnum Bonum good for creamy mashed potatoes and potato purees without becoming gluey. [source]
Salads & Boiling
CulinaryTheir firm, waxy texture holds shape well when boiled, making them perfect for potato salads and as a side dish. [source]
Long-term Storage
HouseholdMagnum Bonum is renowned for exceptional storage capability, keeping for 4-6 months or longer in cool, dark conditions with minimal sprouting. [source]
Garden Ecology
WildlifePotato plants provide food and habitat for beneficial insects and support biodiversity when grown with companion plants in diverse gardens. [source]
Harvest Tips
Harvest Magnum Bonum as a maincrop potato after foliage has mostly died back (110-130 days after planting). Dig carefully with a fork to avoid bruising large tubers. Harvest on a dry day. Brush off soil gently; do not wash before storage. Cure tubers in a cool (50-60°F), dark place for 1-2 weeks to harden skin before long-term storage.
Fun Facts
- 🌱 Magnum Bonum is a Victorian-era heritage potato introduced in the 19th century and remains one of the largest-tuber potato varieties, often producing tubers weighing 1-2 pounds each.
- 🌱 The name 'Magnum Bonum' comes from Latin, meaning 'great good,' reflecting this variety's reputation for abundant harvests and reliable storage.
- 🌱 This variety is notably resistant to many modern potato diseases and prefers cooler climates, making it a favorite among heritage seed savers and heirloom garden enthusiasts.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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