Green Bean Growth Stages

The common bean (Phaseolus vulgaris) may be a single species but includes countless varieties and cultivars with varying traits. Some produce beans in inedible pods that must be shelled before eating. Others are harvested when the pods are immature and tender — these are commonly called green beans.

In other words, a ‘green bean’ is not just one type of bean plant. Instead, this term refers to countless varieties grown for their tender, immature bean pods. Both the pods and the seeds contained within are 100% edible.

In this article, I describe the most important green bean growth stages. You’ll learn a bit about everything from germination to flowering and pollination and some expert tips and tricks for growing better beans.

Conditions for Growing Green Beans

Green bean plants are annuals in the legume family. Most varieties are planted in the spring and harvested in early summer. Some popular green bean varieties you can grow include ‘Blue Lake Bush’, ‘Tendergreen’, and ‘Kentucky Wonder’.

Each bean variety will likely come with its planting guidelines. However, all green bean plants have very similar needs:

You can easily grow green beans in USDA Zones 2 through 11. Daytime air temperatures between 65 and 85°F — or soil temperatures of 70 to 80°F — are ideal for growth.

Green beans like full sun. Too little light can interfere with pod production and leave your bean plants at risk of nasty fungal diseases.

Plant beans in rich, well-draining soil for the best results. Any high-quality garden soil will work well. Weeds can be an issue for the plant’s shallow root system. Take steps to prevent weed growth at the start of the season and hand-weed carefully as needed.

Green beans require 1 inch of water per week on average. This water can come from natural rainfall or irrigation. Note that green beans don’t need much fertilizer (if any) if the soil is high in organic matter. I recommend testing the soil at the start of the season and amending it with aged compost if necessary.

If you opt to grow pole beans (I’ll touch more on this in one of the next sections), you’ll also need to provide some type of support. Wood, string, and wire supports are all suitable options. Supports should be at least 6 feet tall and should be installed before germination or transplanting to prevent damaging the root systems.

Growing Green Beans

Green Bean Growth Rate

Green beans come in a few different varieties. You may already be familiar with bush, pole, and half-runner beans. These three categories all have to do with the beans’ growth habits.

Pole beans are climbers and require structural support like a trellis or sturdy wires. They are also indeterminate, which means they continue growing even after flowering begins. These bean plants can grow 15 feet or taller and produce several harvests yearly. 

Bush beans, as the name implies, do not climb. They don’t require support and take up less space than their climbing cousins. In contrast to pole beans, bush beans grow to a certain height and stop before flowering. These varieties normally grow up to 2 feet tall.

Half-runner beans share characteristics of both pole and bush beans. They have a climbing habit but normally only get 2 to 3 feet tall. You don’t need to support half-runners with a trellis or similar structure, but it can help keep the plants tidy. 

Growth Stages of Green Beans

On average, it takes green beans 50 to 60 days to go from seed to being ready to harvest. Bush beans mature slightly faster than pole beans and half-runner beans.

You may get more than one harvest from your bean plants after maturity (some varieties produce up to 12 separate harvests in a season!). Pole beans and half-runners are commonly produced throughout the season. Bush beans, however, may only produce one big harvest per plant.

Though there are some innate differences in how these green beans grow, you don’t need to learn three different life cycles. Remember that there are subtle distinctions in how bush, pole, and half-runner beans typically grow.

1. Seed Germination

Bean seeds provide a unique glimpse into the anatomy of a plant seed. You may even remember splitting the seeds in half as part of an early science class to inspect the cotyledons and other embryonic structures inside.

While the seeds contain several pieces, I want to highlight just a few of the most important:

  • Seed coat — The outer layer covering the entire seed.
  • Radicle — The seed’s first root. It can often be seen by cutting open a bean seed.
  • Cotyledons — The seed’s embryonic leaves. They act as the primary energy source while the seedling sprouts. If you split a bean down the middle, the cotyledons make up the bulk of each half.
  • Plumule — The seed’s primary shoot. This is the top of the main stem and will produce new shoots and leaves once the seedling sprouts.

According to Cornell University, the ideal temperature for bean germination is 70 to 80°F. You can expect seedling emergence within 8 to 10 days in these conditions. Bean seeds can germinate when soil temperatures are as low as 60°F (and sometimes below), but emergence may not occur for 14 days or longer.

Germination begins when the bean seed imbibes water through its seed coat. This naturally happens when the seed is planted in moist soil. However, some gardeners opt to soak their seeds overnight to speed up the process.

Once a bean seed absorbs enough water, physical germination kicks off. It’s normal for the seed coat to crack or split open as the cells inside the seed start rapidly dividing. It doesn’t take long for the radicle and the cotyledons and plumule to emerge from the seed shortly after.

2. Seedling Emergence

You’ll know your beans have successfully germinated when the plumule and cotyledons emerge from the soil. If the soil is warm enough, this should occur 8 to 10 days after planting.

As mentioned above, the cotyledons are a crucial energy source for the young bean plant. While bean cotyledons do not photosynthesize (contrary to popular belief, some cotyledons perform photosynthesis!), they contain tons of energy previously stored inside the seed itself. I like to think of a seedling’s cotyledons like the yolk of a bird egg.

Cotyledons vary in appearance from one plant type to another. In the case of bean seedlings, the cotyledons are almost the same shape and size as the original seed. 

All new growth will come from the plumule or the small shoot protruding from the center of the cotyledons. The seedling’s first true leaves (the first to appear after the cotyledons) typically emerge within 2 to 3 days. Some bean seedlings sprout from the soil with their first true leaves already visible!

It’s normal for the seedling’s cotyledons to wither away shortly after the true leaves emerge. I mention this because some gardeners worry that their seedling has fallen ill when they see the lowermost leaves turn yellow or brown. This happens because the seedling can now photosynthesize thanks to its mature foliage and no longer needs the cotyledons for energy.

3. Vegetative Growth

Green beans grow incredibly quickly once they become established. New true leaves will continue to grow from the top of the main shoot as the bean plant gets taller and wider.

Top growth is not the only thing growing during this stage. The green bean’s root system also expands to support the plant’s rapid growth. 

Bean plants tend to have a primary root (once the radicle) extending up to 2 feet deep. However, most of the root system comprises fibrous roots that fill the space directly beneath the bean plant. These roots are fairly delicate, so care should be taken not to disturb the soil around growing bean plants.

If you plant a pole or half-runner variety, the bulk of climbing will occur during the vegetative growth stage. According to Texas A&M University, green beans climb via twining stems. The vines wrap around available supports (unlike other climbing vegetables like peas that climb using tendrils).

4. Flowering

A green bean plant may start flowering 50 to 80 days after sprouting. Green bean flowers are typical of the legume family. Most varieties are pink or magenta and have sweet pea-like petals.

Green Beans Flowering

While the most obvious difference between bush and pole beans is their overall growth habits, flowering is also a bit different. Bush beans tend to produce all or most of their flowers simultaneously. Pole beans, however, are more apt to produce flowers continuously until the year’s first frost.

5. Pollination

Green beans are easy to pollinate. Plants are self-fertile and have everything necessary to produce viable seeds from a single flower. The flowers of a bean plant are special because they usually pollinate themselves before they even fully open. Insects and the wind account for a very small percentage of pollination.

With that said, cross-pollination between plants can improve genetic diversity (which is essential if you plan to save some of your harvest to plant next year!).

6. Pod Formation

The pods will develop as soon as the flower petals drop from the plant. You should see very small, slender pods scattered along the plant within 7 to days.

Green Beans Pod Formation

7. Seed Development

Green bean pods can grow to be several inches long before the seeds inside begin to fill out. After about 14 days, bumps form along the pods, indicating where the seeds are inside. 

8. Maturation

While the previous stage is the best time to pick green beans for eating, the plant’s life cycle isn’t yet complete. Any seeds that grow additional plants must be left to fully mature on the stem. Wait until the pod and the seeds inside are dry and brown before collecting the seeds for storage. This occurs 60 days after flowering, on average.

When to Harvest Green Beans

Harvest green beans when they are about the thickness of a pencil and have a nice, tender snap when broken in half. The seeds inside should be only partially developed for the best texture and flavor.

Once the harvest starts, expect to pick fresh green beans from the plant nearly every day. This will encourage the bean plant to produce as significant a harvest as possible.

For more green bean growing tips, here’s a link to Companion Plants for Green Beans.

FAQ Green Bean Growth Stages

Should I grow pole or bush beans?

Both bush and pole beans are easy to grow, and a single plant can produce a great harvest. Bush beans are best for smaller gardens where space is a concern. Pole beans are more productive on average and usually produce beans later in the season than bush beans.

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.