Garden
How to Grow Fava Beans as a Cover Crop and Get Free Fertilizer
- In winter, a couple of my garden beds get less sun and stay more damp so it’s difficult to grow a food crop. I usually let the soil rest at this time, but by that, I don’t mean I leave the garden beds bare.
- Even if you only garden three seasons out of the year, you should never leave the soil exposed and empty.
- Winter rains could lead to soil compaction, especially in hard clay soils. The earth could erode, washing nutrients away if there are no plants and roots to reign them in.
- Some people simply throw a layer of mulch on the ground and call it good.
- But I like to grow a cover crop—and I especially like to grow fava beans (a dual-purpose cover crop) as part of my overall lazy gardening strategy of more food, less work. Here’s how you can do it, too.]\
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Benefits of growing fava beans as a cover crop
- As a legume, fava beans are not only delicious (with edible leaves and flowers), they also fix nitrogen in the soil; that is, they put in more nitrogen than they take out.
- Fava beans are ideal plants for fall because they germinate quickly, thrive in cold weather, and are one of the few fruiting plants that tolerate some shade.
- In milder climates where fava beans can be overwintered, they require minimum watering in winter, especially in wetter climates. And if your garden is less than perfect, rest assured that fava beans can easily be grown in deficient soil or clay soil (after all, their job is to make it better).
- However, fava beans are happiest in rich loams with good drainage. At the very least, try not to let the plants stand in waterlogged soil for too long.
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How to plant fava beans in fall
- Fava beans (Vicia faba, also called faba beans or broad beans) are actually not a bean but a type of vetch, a common cover crop and forage crop.
- They’re cool-weather plants that should be sown directly in the garden in fall to enrich the soil for the following spring.
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Step 1: Inoculate your seed.
- To maximize the nitrogen-fixing capabilities of your fava bean crop, seeds should be inoculated before planting. Doing so helps get the right kind of rhizobia bacteria into the soil that your plants need for their nitrogen stores.
- Recommended fava bean inoculants:
- Exceed Pea and Bean Inoculant
- Mountain Valley Seed Legume Inoculant
- Though it isn’t necessary, you can also soak fava bean seeds for a few hours to speed up germination. This is especially helpful if the weather is still dry when you plant and you want to ensure the seeds germinate.
- You can kill two birds with one stone by sprinkling a bit of inoculant in the water and stirring it around while your beans are soaking. This will ensure some inoculant sticks to the seeds when you plant.
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Step 2: Sow seeds about 6 inches apart and 1 inch deep.
- Space your plants in rows 12 to 18 inches apart to give them room to breathe; fava beans can grow quite bushy.
- Keep the soil consistently moist but not soggy. Sprouts will appear that first week, and grow into 6-inch seedlings within a couple of weeks.
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Step 3: Add mulch.
- Once they reach 6 inches in height, add 2 to 3 inches of straw (or another organic mulch) around the plants, being careful not to pile the mulch against the stems (which could lead to rotting).
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Step 4: Add support for your plants.
- Fava beans are tall, thin, and top-heavy plants that require minimal staking as they mature so they don’t flop over under their own weight.
- They’re well suited for those conical wire tomato cages that, ironically, don’t do a super job of supporting indeterminate tomato plants. But they’re fantastic for fava beans!
- You can also support them with bamboo teepees, or a combination of both for an aesthetically pleasing grouping.
- Fava beans grow 3 to 6 feet tall and produce clusters of beautiful, orchid-like flowers. The flowers turn into dense green pods that sometimes reach 8 inches long or more.
- With proper mulching, fava plants only need an inch of water a week, and sometimes less if they’ve had rain.
- Like other legumes, fava beans do not need nitrogen fertilizer (assuming your soil is halfway decent—at most, you can amend with compost after you’ve pulled out last season’s plants).
- They have the unique ability to work with the rhizobia in their roots to make nitrogen from the air, and over-fertilization may actually stunt production of the pods.
- The leaves are susceptible to fungal rust, an airborne plant pathogen, so keeping them dry with good air circulation is important.
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When and how to turn fava plants into the ground
- When you should cut back your fava bean plants depends on what you’d like to get out of them.
- If nitrogen fixing is the goal, they’re best cut back when they’re flowering (but right before they start to fruit).
- That’s because by the time a pod is formed, most of the nitrogen in the roots goes to the seed (that is, the beans) and the plant will have very little nitrogen to release back into the soil for other plants to use.
- Fava beans can withstand temperatures down to 15°F, so if you sowed seeds right around six weeks before the first frost, your plants should be flowering by the time a hard freeze hits.
- They’ll die back naturally, at which point you can cut them down at soil level, leave the roots in place, then spread the dead foliage across your garden bed to decompose over winter.
- If you don’t get a hard freeze, just make sure to cut down your plants while they’re flowering and let the foliage decompose in place (where they’ll act as a mulch over winter).
