How to Grow Onyx Black Bean
Wikimedia Commons
Onyx Black Bean
Phaseolus vulgaris
vegetableOnyx is a bush bean variety prized for its glossy, jet-black seeds and reliable productivity. These compact plants produce abundant pods containing nutrient-dense black beans that are excellent for cooking, storing, and eating fresh as a green bean. The variety is known for its disease resistance and adaptability to various growing conditions.
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Example Onyx Black Bean timeline · Pittsburgh, PA (Zone 6b)
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Plant Onyx Black Bean
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 Onyx Black Bean
Around Jun 6≈ 50 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Onyx Black Bean dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9; plant after last frost date
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Seedling
1-2 weeksSeed germinates and first true leaves emerge; plant is 2-4 inches tall.
Keep soil consistently moist but not waterlogged. Thin seedlings if overcrowded. Provide full sunlight.
Vegetative
2-3 weeksPlant develops bushy foliage with multiple branches; 6-12 inches tall. Multiple leaflet sets form along stems.
Maintain consistent watering. Apply mulch to retain moisture and suppress weeds. Monitor for pest activity.
Flowering
1-2 weeksSmall, delicate white or pale purple flowers appear in clusters along stems. Plant reaches full height (12-18 inches).
Continue regular watering but reduce nitrogen. Flowers typically self-pollinate. Avoid disturbing plants during flowering.
Pod Development
2-3 weeksGreen pods form and elongate to 4-6 inches. Interior beans begin filling pods with visible seeds bulging through pod walls.
Water consistently to support pod growth. Support with stakes if needed. Begin harvesting green beans when pods are tender (6-7 inches).
Maturation
2-3 weeksPods turn from green to black as beans fully mature. Seeds are hard and glossy black inside brittle pods.
Reduce watering to allow plants and pods to dry down. Leave mature pods on plant for 2-3 weeks until completely dry if storing as dry beans.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick beetles and eggs; use row covers; spray with spinosad or neem oil; plant trap crops
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Use row covers early; intercrop with resistant plants; remove plant debris; spray with kaolin clay or neem
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Increase humidity; spray with water to dislodge; use miticide if severe; maintain healthy plant vigor
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Spray with water; introduce beneficial insects; use insecticidal soap or neem oil
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Remove infected leaves; improve air circulation; avoid overhead watering; apply sulfur fungicide
Uses
Dry Bean Cooking
CulinaryOnyx black beans are highly prized for soups, stews, rice bowls, and refried beans. They have a creamy texture when cooked and rich, slightly earthy flavor that complements many cuisines. [source]
Fresh Green Beans
CulinaryHarvest young pods as tender green beans for fresh cooking, steaming, or stir-frying. They are tender and flavorful when picked at optimal size. [source]
Nutritional Content
MedicinalBlack beans are excellent sources of plant-based protein, fiber, folate, iron, and antioxidants including anthocyanins. Regular consumption supports heart health and stable blood sugar. [source]
Food Storage & Preservation
HouseholdDry Onyx beans store excellently for months or years in cool, dry conditions without refrigeration. They are ideal for long-term pantry storage and food security. [source]
Pollinator Support
WildlifeBean flowers attract bees and other pollinators, supporting garden biodiversity and benefiting nearby fruiting plants. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
For green beans: harvest pods when 6-7 inches long and pods snap cleanly, typically 50-60 days after planting. Pick regularly (every 2-3 days) to encourage continued flowering. For dry beans: allow pods to fully dry on plant until black and brittle (65-75 days); shell pods when completely dry and store beans in cool, dry conditions.
Fun Facts
- 🌱 Onyx black beans are nitrogen-fixing legumes that naturally enrich soil with usable nitrogen through a symbiotic relationship with soil bacteria, reducing the need for fertilizer in subsequent plantings.
- 🌱 The dark black color of Onyx beans comes from anthocyanin pigments, the same powerful antioxidants found in blueberries and purple cabbage, making them a true superfood.
- 🌱 In the 'Three Sisters' companion planting method, beans like Onyx fix nitrogen for corn and squash while the corn provides vertical structure for bean vines and squash shades the soil.
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