Planting Field Beans Guide What You Need To Know

Field Beans A Green Manure Cover Crop

You can use winter field beans as a cover crop to add some nitrogen into the soil, prevent weeds from moving in, and grow them for use as green manure.

They can grow on almost any soil but prefer flat, well-draining soils, a location with full sun, and do not tolerate standing water.

They are a cool-season crop, also called winter field beans, but not an actual winter-season one like winter rye since they will die off when the weather gets to about 12F(-9C).

Bean plants grow quickly and can provide ready-to-eat beans in as little as two months. Beans are the second most popular garden vegetable and one of the oldest we have cultivated.

It grows between 2 and four feet tall and is considered a bush bean and not a vine, from what I could find, so it does not need poles or a trellis.[9]

Are Field Beans an Annual or Perennial

Field beans are a cool-season annual plant that must be planted and grown from seed each year.

The plant will die off when the weather goes below 10to 15F (-12 to -9C).

Field Beans Seeding Rate

4 seeds per square foot of our garden are the average seeding rate I use.

If you use a grass/legume mixture for a pasture, the recommended rate is 25%.

Where Do Field Beans Grow

In the US, they are rated as hardy to Zone 8.

If the temperature does not go below 10F and the plant gets 60 days after germination, you will have enough time for the beans to fully mature and pod.

How to Identify Beans

Winter Field Beans Growth Stages

1) Germination
2) Seminal Taprooted Stage
3) Fragmentation of the Taprooted Plant
4) Clonal Growth Stage
5) Flowering
5) Fruiting (Pod creation)

Field Beans Germination Time

Multiple factors will alter how long it takes for our field beans to germinate. The seeds planted depth, available moisture, and temperature all change the germination speed we will see.

Under ideal conditions, we will see them sprout within 7 to 14 days. To see sprouts within this time, we need the soil to be around 70 to 80 degrees F. If the weather is on the cooler side, say 60 F, it will take 14 days and could even take 20.

The soil's temperature needs to hit 70F, so if we wait until daytime temperatures hit 75F, we will see the quick germination time.

We also want our soil to be evenly moist but not so wet that it looks like soggy soil.

Growing Field Beans

Field beans do not perform well in heavy clay soils since they tend to hold onto too much water and have lousy drainage.

If that is the type of soil you have, you will have to add some more organic matter. A slow way to improve the ground would be to allow a different cover crop to grow over a season or two to naturally add more organic matter, but that's a slow process.

A faster way would be to break up 1 to 2 feet of the soil and mix some extra organic material like compost or manure to quickly improve drainage.

The last option I can think of is to use raised beds and add quality soil to them.

Field beans perform best in a pH between 5.8 to 6.5. If your soil pH exceeds 7.2, it can result in chlorosis problems due to iron and zinc deficiencies.

Now use a spade to help break up the ground to provide better aeration. Then use your garden rake and level your garden plot.

You will plant the field bean seeds between 1 to 2 inches deep. We want the seeds deep enough to access moisture while allowing them to sprout as quickly as possible.

Water well, and ensure your garden plot is nice and moist.

Field beans do best in relatively low humidity since bacterial and fungal disease problems are reduced.

How Tall Do Field Beans Grow?

It grows to a height between 2 to 4 feet (60 to 120 cm), and this is just slightly taller than what broad beans reach.

Killing Winter Field Beans Cover Crop

When we use the plant as a cover crop, the goal is for it to protect and enhance our soil.

To keep the nitrogen in our soil over the winter and early spring season, we need to prevent them from moving into flower.

During the vegetative stage, the plant will have 40 percent nitrogen in the soil, with the other 60 percent in the leaves and stems.

If we let the pods develop, 80 percent of the nitrogen moves to them.

So if you plan on using the plant as a source of green manure tilling them into your soil before they flower is ideal.

Field beans are easy to till into our soil, and I found one place stating that the small-seeded variates are best when you want to use them as a cover crop.[4]

How Late Can You Plant Winter Field Beans

For planting field beans that we want to have a finished flowering crop from, we need to determine when the weather will reach below the temperature that will kill the plant.

We need to have the seeds in the ground at least 70 days but preferably 80 days in cooler weather before we expect the temperature to hit around 12F(-9C).

It will take 60 days from the time of the plants sprouting to get completed bean pods, so we want to give a little extra time for germination.

Winter Field Bean Benefits

Protection for our garden soil over the winter
We can till it into our ground as green manure to help improve our soil.
Like all beans, they are drought tolerant.
Being a member of the legume family, they will collect nitrogen from the air and move it into our soil with the help of Rhizobium bacteria.
Creates large amounts of organic matter above ground in the second season.
Like other cover crops, it mixes well with other plants.
Grows well in most soil types.

Summary

While field beans attract many beneficial insects to our garden, you want to ensure you do not grow them before any root crops. Field beans can host root-knot nematodes in our soil.

Root-knot nematodes will feed on our plant roots and can cause severe damage or even kill them.

Winter field beans are a great cover crop and a useful source of green manure. To maximize their use as green manure, we want to till them into our soil before they flower.

We can still let them flower, collect the bean pods, and use the plant as a source of green manure, but they will have less nitrogen.