Runner Beans Not Germinating? Here’s Why

Runner beans are delicious and beautiful plants – that is, if you can get them to grow. If your runner beans are not germinating, there are four primary causes to look for. Luckily, they’re all relatively fixable problems!

The most common causes of runner beans not germinating are poor irrigation, adverse weather, damage from bugs or birds, and infrequent or poor harvesting.

Let’s explain those in-depth so that we can get your beans up and running again in no time!

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4 Reasons Your Runner Beans Are Not Germinating

As mentioned above, there are four primary reasons that your runner beans may not set their pods. Some of them are easily fixed, while others will require a rework of your planting space. Fear not, though, as we’re here to guide you through the process.

1. Irrigation & Watering

Just about all life on earth requires water – including runner beans. If your planting setup’s irrigation isn’t up to snuff, you’re likely to run into issues with your plants’ health. Just like other beans, runners require a rather hefty amount of water to ensure their roots don’t dry out.

Runner beans generally grow very well in pots, which is how I personally would recommend you plant them. Just be sure to use a pot large enough for the whole plant (minimum 20 litres, preferably up to 50 litres). Using a large pot will allow more water to be held and will prevent your plant’s roots from drying out. Alternatively, you could use a container with a water reservoir to keep the water levels healthy.

Another note is that you should water roughly 5 litres of water per sq./m twice a week. And do not spray or mist water your beans. Not only does this not help the plant, but it can actively deter bees and other friendly bugs that are vital to your garden’s health.

Be sure to water your beans more than you might water other, less needy, plants. And on extra hot or windy days, give them a bit of extra water. If you’re thirsty, they’re likely thirsty too.

2. Bad Weather

Weather affects pretty much all plants, though some are able to handle it a bit better than others. Runner beans are generally best to be planted in September and grown over winter, as hot weather easily does them in. If the weather is getting extra hot (especially at night), it may be best to bring your potted plants indoors overnight and leave them out during the day to get sunlight with some extra water and care.

The reason for this is that hot weather interrupts the germination of pollen grains, which in turn disrupts the pollination and fruiting processes. Growing your beans over the autumn and winter will generally improve your yield and make them, generally, happier and healthier.

As runner beans tend to be grown vertically with the use of a trellis or other support system, windy days can also be dangerous for your beans. If it’s incredibly windy out, you may be served better by moving your plants indoors near a window. Just remember, the beans still need a good amount of sunlight, so be careful with where you place them inside.

3. Birds and Bugs

We love our beans. There’s just one problem – so do insects and birds! They can come in many forms, but there are some ways to discourage unwanted insects and birds from turning your pretty beans into a snack.

One of the more common culprits of runner beans not germinating is bees! They, at times, will only take the nectar of the flowers, leaving pollen alone and untouched. They do this by biting a hole at the base of the flower, making the flowers unattractive to other insects that may have helped with pollination.

Many birds like to peck at the flowers of your plants, especially house sparrows. They will damage the flowers in the process, preventing pollinating insects from being able to access the, well, pollen. While birds are cute on their own, when they mess with your garden? That means war. But rather than waging all-out scorched-earth warfare, it’s often easier to think smarter than the birds (which hopefully isn’t too hard).

Try putting your plants in a wired protective mesh – it’s super common to see this in gardens, and it’s for one reason. The mesh protects your plants from birds while allowing insects access to pollinate. Growing more attractive (colourful and pollen-rich) flowers to distract birds and insects can also help here.

If you use insecticide or aphid treatments, be careful with it. Ensure it doesn’t harm bees or other friendly bugs, and try to apply it in the evening to cut the risk posed to bees.

4. Harvesting

This is a rather simple fix that, unfortunately, may require simply starting over. If you don’t harvest your beans every 2-3 days, you run the risk of them seeding. This will result in your beans not growing any more pods and will require that you replant and harvest correctly the next time around.

And if your beans are getting rather large, it’s a sign that you waited too long. It’s best to pick beans when they’re small and tender, rather than waiting for them to swell. Once they’ve gotten too large, the beans will not taste as sweet, nor will they be quite as enjoyable to eat in general.

Other Reasons Your Runner Beans Are Not Germinating

Here is a small list of things that may also affect your beans’ growth:

  • Proper soil and nutrients are important. Plan ahead and lay manure or compost in the soil and till it in the autumn before you plan on planting. This will ensure you have extra-healthy soil.
  • If the pH of your soil is below 6.5, lime it. Check out our article on grass seed to see how to test soil pH.
  • If sowing seeds outside, wait until frosts have gone away. This will generally be mid-May or June.
  • Planting in sheltered areas (a greenhouse) will encourage bees to come and pollinate and discourage birds and other pests.
  • Mulch on the roots will improve your plant’s health.
  • Don’t plant in the same place every year. This will make it harder for pests to set up homes in your garden.
  • If you have flowers that regularly get bees’ attention, consider placing them elsewhere to let the bees find your runner beans.

Final Thoughts

Runner beans are delicious and beautiful plants that come in a wide variety of forms. If they’re not germinating, there are a few things to look for. Specifically, you want to look at the weather, soil, irrigation, and surrounding birds and insects to see why your plants may be having a hard time.

If you need more help, check out this article from the RHS on growing runner beans. Now get gardening!