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Frost Bitten Broad Beans – Symptoms and Solutions

Posted on 11. Mar, 2010 by Tracey in Pests

Frost is one the things that gardeners always have to look out for when growing tender plants during the winter and early spring months.

Unfortunately even though my broad beans had a cloche over them, the outer rows have succumbed to the effects of frost. Please see my February Growing Update for more about my Broad Beans.

How does Frost Form?
On clear cold nights, heat loss from surfaces occurs and makes the surrounding areas colder than the air. In these conditions ice crystals form and although transparent appear to be white on soil and plants.

Black Broad Beans Leaves

What affect does Frost have on Plants?
Hardy plants have a tolerance to cold temperatures and others like tender vegetables do not. Tender vegetables include any vegetables that have to be sown in a greenhouse or under cloches during the months of the year when frost is still present. In the South of the UK, frost is present during the months of October to the end of April.

Tender Vegetables include: Tomato’s, potatoes, cucumbers, lettuce, usually any vegetables with a high water content and leafy vegetables.

Once frost has formed on a plant stems, the ice crystals can pierce the stem cells, freeze the water in the cells and cause damage and/or death. The morning sunshine often causes more problems when the plant cells are warmed up quickly which cause them to expand at a fast rate sometimes bursting the already fractured plant cells. The damaged plant cells are unable to pull up the water from the soil, therefore the plant collapses and dies.

How do I know when plants have been damaged by frost?

Frost Symptoms:

• Plant stems become distorted or twisted,
• Plants stems and leaves turn black,
• Plants become weak and collapse,
• Some plants turn brown and leaves turn translucent

Is there anything I can do to stop my plants getting frost bitten?

Here are a few tips for covering your plants:

When Buying look for:

Horticultural Fleece covering Plot

• Horticultural Fleece – this is a thick weave white material that doesn’t allow frost to penetrate through its material.

  Water and light cannot go through the tight weave material so it is only a temporary measure for covering when frost is due, it needs to be removed during the day. It can be re-used and hand washed.

• Fleece Plant Jackets – these are pre-formed different sized jackets to cover a range of plants.

For Borrowing & Recycling:

• Plastic Fizzy Drinks Bottles – carefully cut the bottom off, screw on the lid and you have a homemade emergency cloche to protect your smaller seedlings.
• Plastic Milk Cartons – make sure the cartons are cleaned and dried then cut off the bottom and place over plants.
• Tupperwear Boxes or Plant Pots – These can both be used to temporarily cover your seedlings to protect from frost overnight.

For more tips on recycling in your garden – please visit Make It And Mend It.

Other Posts you may by interested in:

• 10 Vegetables That can Survive the Cold
• The Affects of Snow, Ice and Cold on Your Vegetable Garden
• Blackfly or Black Bean Aphid on Broad Beans
• Vegetable Harvest – Discover Broad Beans