Broad Bean Trial Update

 Winter has finally arrived with the start of a cold snap estimated to last about a week. Minimum temperatures of -2 ℃, -4 ℃ and -3 ℃ respectively were recorded by my Davis Weather Station during the early hours of Wednesday (7th), Thursday (8th) and Friday (9th). That was enough to bring the broad bean trial to an end.

The trial had two objectives:

  1. Is it possible to avoid blackfly infestations by sowing broad beans late?
  2. How big a crop do late-sown broad beans yield?
It only remains to define what 'late-sown' means. For this trial, the first beans were sown on 5th August and the last beans at the end of August. The variety chosen for this trial was Luz de Otono. The weather for September, October, and November was warm/mild though August was dry and hot and the seeds/plants needed some additional watering.


  1. A very minor blackfly infestation on the earliest sown beans was treated successfully with SB Invigorator. No blackfly observed on the broad beans sown after the middle of August. So, success!!
  2. After showing some early promise, the conversion of broad bean flowers into pods was almost non-existent (probably, less than 1%) - and, there was no shortage of flowers! So, failure!!
The pod below, featured in this post, was picked following the December frosts. It had grown but not as much as I had expected.

Broad bean picked on 9th December after frosts

The contents of the pod (frost-damaged) are shown below ...

Contents of the above broad bean pod

... six beans per pod is fine, we just needed more pods.

The broad bean plants do not look strong enough to survive the winter so I will be adding them to my hot composting bins.

Future Plans

In 2023, I will give this another try. Clearly, I need to start the process earlier than August 5th. So I will be sowing two lots: one lot at the beginning of June and the other lot at the beginning of July. Success or otherwise will be based on the same two criteria: yield and blackfly tolerance.


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