How to Grow Black Beans in Your Garden

When to Grow Black Beans

Although you may be anxious to get bean seeds in the ground, patience is key when it comes to planting black beans. Black beans don’t transplant well, so it’s best to directly sow them in gardens in spring after the danger of frost has passed and soil temperatures are above 60 degrees Fahrenheit. Planting bean seeds too early can slow down germination or even cause seeds to rot before they sprout.

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How to Grow Black Beans

Before planting black beans, choose an appropriate planting spot with well-draining soil and plenty of sun. If you’re growing pole or vining-type black beans, install trellising before planting to avoid disturbing delicate plant roots later on. Bush-type black beans generally won’t need trellising, although they can be supported with small bamboo stakes if needed.

Planting

To boost germination rates, soak black beans in water for 12 to 24 hours before planting. You can also use this time to inoculate bean seeds with rhizobium bacteria to boost harvest rates and improve nitrogen fixation.

Once you’re ready to plant, directly sow the bean seeds outdoors by burying the seeds about 1 inch deep in garden beds or pots filled with a rich potting mix. Space individual seeds 6 inches apart in rows located 15 to 18 inches from each other.

If you’re using a trellis for pole beans, install the trellis at planting time and then sow the beans a few inches away from the trellis to provide extra support to the bean plant’s growing tendrils. While it’s not required, laying a sheet of damp paper towel over bean seeds after planting can prevent birds and other critters from gobbling seeds up before they sprout.

Care

Black bean seeds take about eight to 10 days to germinate, but the plants grow quickly once they’ve sprouted. When the seedlings are a few inches tall, apply a thin layer of mulch over the soil line to block out weeds and reduce soil moisture evaporation. Remember, black beans don’t compete well with weeds, so it’s important to stay on top of weeding through the growing season to come.

To keep plants healthy, black beans should be watered with about 1 inch of water per week, but don’t let plants sit in soggy soil. Since beans fix nitrogen on their own, these plants generally won’t need much fertilizer, but you can give bean plants a boost with a side dressing of low nitrogen fertilizer, compost, or compost tea if they look like they need a pick-me-up.

Light

Black beans are full sun plants that need a minimum of six to eight hours of bright light daily to grow. Select a growing spot that receives plenty of bright, unobstructed light throughout the day to ensure your plants grow quickly and produce a big harvest of beans.

Soil

Loose, well-draining soil with a pH of between 6.0 and 6.5 is best for black bean plants. These plants may struggle in clay heavy gardens, but dense clay soils can be improved with some compost or other organic matter. In fact, adding compost to any soil type will make black beans grow more productively.

When to Harvest Black Beans

While snap beans are harvested when the pods are still tender, black beans should be allowed to dry fully on the plant. Harvest season usually starts towards the end of summer when the bean pods dry out and develop a straw yellow to brown color. Black bean pods that are still soft and green need more time to mature, although beans should always be harvested before a hard freeze even if they’re not quite dry.

To harvest, pick pods one at a time by cutting the pods from the plant with scissors or clip the entire plant off at the soil line using garden pruners. Leaving the plant’s roots in the soil will fix more nitrogen into the earth and help replenish soil nutrients. As you harvest, handle beans pods carefully to keep them from splitting open and spilling bean seeds on the ground.

After harvesting, allow the beans to continue to dry in a protected spot with good air flow until the pods are completely dry and brittle. Individual pods can be dried on screens or drying racks, while bean plants can be hung upside down with a bit of twine to dry. Once the beans are fully dried, shell the pods by hand, and store the dried beans in airtight containers in a cool, dark location.

10 Tips for Growing Black Beans

• Keep leaves dry: Water beans at the soil line to keep leaves dry and mildew-free.
• Watch for pests: Pests like bean leaf beetles, aphids, leafhoppers, and slugs will sometimes target black beans. If you find any damage, remove larger pests by hand and treat for smaller pests by spraying plants with a garden hose or organic insecticidal soap spray.
• Mulch correctly: Keep mulch lines several inches away from bean stems to avoid rot.
• Help plants climb: If vining beans are struggling to climb, plant clips or garden twine can be used to loosely fix pole beans to trellising.
• Extend the season: Adding black plastic mulch to gardens helps soils warm up faster in spring and allows for earlier planting.
• Try companion planting: Scented herbs, like catnip and summer savory, and flowers, like nasturtiums and marigolds, can keep bean plants naturally pest-free.
• Rotate crops: Don’t plant beans in the same location year after year to avoid a buildup of soil pests and diseases.
• Plant extras: To boost germination rates, plant two bean seeds per planting hole and then thin out the weakest seedlings once the bean seedlings are several inches tall.
• Plant bean “eyes” down: Black beans sprout a little faster if the seeds are planted with the bean “eye” facing down.
• Water properly: Beans need a bit more water after flowering but watering should be reduced or stopped when the bean pods begin to yellow.