Runner beans will usually be planted out in May, mid-May inside a polytunnel, and from the end of the month outdoors. In early May, in preparation for the transplantation of runner beans sown indoors, it is a good idea to begin to prepare the planting area by creating a runner bean trench. This is a traditional way of ensuring that these hungry plants get all the nutrients that they need as they grow. Here are some tips to help you create a runner bean trench in your polytunnel. It is important to do this at least two weeks before you intend to place the plants in the polytunnel as this will give the soil time to settle. If you need more help growing runner beans, take a look at our runner bean growing guide.
Take care not to disturb polytunnel foundations or a trenched cover
When deciding where to grow runner beans in your polytunnel, it is important to make sure that you do not dig a runner bean trench too close to the ground poles or trenched polythene around the edge of the tunnel. Make sure you do no digging that could de-stablise the structure.
Suggested dimensions for a runner bean trench
Once you have decided where you will be growing runner beans, consider how your runner beans will be supported. Think about digging the trench in a location which makes it possible to create a support structure. Support is very important for these vigorous vining plants. Once you have decided on a location within the polytunnel, dig a trench that is, ideally, approximately 60-90cm wide and 60cm deep. A smaller trench can be sufficient, though these dimensions are ideal to provide an optimum growing area for runner beans.
What to put in a runner bean trench
Once you have dug your trench, it is time to fortify the soil with the addition of a good quantity of compost. You should also use well-rotted manure and other organic matter. You can place also place:
- grass clippings
- kitchen scraps
- layers of other compostable materials
in the trench to compost before back-filling with the topsoil you have removed. The trench method can also be used to make fertile planting pockets. This is useful for other hungry crops such as pumpkins or squash.
Placing supports for runner beans
Once you have created the trench, it is time to create the support for your runner beans. The support can be as simple as a row of garden canes, or a far sturdier trellis type structure. After everything is in place, it is simply a case of waiting a couple of weeks and then sowing your runner beans, or transplanting your pot grown plants.