Aussie gardener with a question!

Aussie gardener with a question!

Hi all! We planted snow peas earlier this winter and the plants that grew were incredibly healthy looking and we looked forward to a bumper crop. However, in the last few weeks the flowers and immature snow peas have been withered and we haven't been able to harvest a single one. Now the plants themselves are dying and we don't know why. We garden organically so haven't used any fertiliser besides kitchen scrap compost and have been watering regularly. What's happened to my poor snow peas? (We're in Central Western NSW, Australia, we have had a bit of snow and some pretty heavy frosts.)
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