With your long vining beans (lima, yard-long, winged), it is very important to prune crops for airflow, and to allow sunlight to get to the soil. When you’re assessing any fruits or veggies that require a trellis to grow, always ask yourself: Is there space for air to flow through the trellis? Chances are once your plants are mature and producing you should be helping to thin them out on a weekly basis to keep them happy and healthy.
The first place to begin are vines that may be growing down toward the ground. Before pruning, see if there is adequate space on the trellis to help train the vines to grow up. Be careful not to train more than 2 vines on any one bar of the trellis. Take care to route the vines where there will still be good flow, and not all piled on each other. A great tool is Velcro tape to loosely attach vines to open trellis areas until they wrap on their own. It’s also important to be gentle when moving vines and take care not to bend or break stems. Once you’ve gotten to the point where vines are surrounding all open areas of the trellis, you can either leave remaining stems to continue growing down, or prune them by cutting above a node of new growth. Pruning the ends and leaving new growth or flowers behind will still allow the vegetables on those vines to mature.
The next thing you’ll want to do to help out these plants with airflow and overall health is pruning. The best place to begin is with any yellowing or damaged leaves. Simply take your shears and cut leaves close to the base of the stem, being aware of new growth nodes coming from that intersection. Damaged leaves with holes in them may be a sign there are caterpillars so make sure to check out the underside of these leaves because that’s often where they will be hiding. During heavy storms we can also see wind damage on delicate leaves, so as long as you’re not removing more than 30% of the foliage, these can be pruned off as well to allow more energy to go toward producing fruit and healthier leaves.
If your plants haven’t experienced much damage, you may have pruned away yellowing leaves but still not have enough clearance for airflow to go through the plant. At this point we focus mostly on the inside of the trellis. Pruning beautiful leaves won’t harm the plant especially if it’s so fluffy you just need to create some space. Prune away the largest leaves in congested areas. Remember the goal is just to allow for air to flow through, so keep with the no more than 30% removal rule of thumb.