During the autumn months in the UK the temperature will drop, so anytime from September through to November you are likely to see the first frost. Frost is basically frozen water – water will freeze when temperatures fall below zero degrees Celsius / 32 degrees Fahrenheit – so on a clear, still autumn morning it’s likely that you’ll see frost as the cold temperature has turned moisture into ice crystals. Plants can suffer frost damage as the moisture / water within their cells will freeze – as the water freezes it expands, rupturing the cell walls of the plants causing damage.
Some plants are able to alter their reactions so they are not affected by frosty conditions – for example some hardy plants react to cold weather by lowering the freezing point of their cell contents (although a sudden frost can catch some plants out as they need a few days of cold weather to alter their freezing point). Other plants will simply drain as much water as possible from their cells during the colder months and then rehydrate during spring.
However not all plants will be able to tolerate frost and it is for this reason that reason that you should monitor the temperature in your garden, at your allotment and in your greenhouse. The simplest way to monitor temperature is to use a thermometer.
What Is A thermometer ?
Basically a thermometer is an instrument which enables you to measure the temperature – our Wall Thermometer is a good example of this.
This budget Wall Thermometer can be used indoors or outdoors and is ideal for use in your greenhouse or garden. Our simplest thermometer it shows the current temperature in both degrees Celsius and Fahrenheit.
The next step up form this simple type of thermometer is to use a max/min thermometer.
Max/min thermometers have been developed to record the maximum and minimum temperatures reached and will feature a reset button to clear those temperatures allowing you to start again. Usually these types of thermometers will show the current temperatures on their display and have a button for you to press to display the maximum and minimum temperatures reached.
Monitor the temperature outdoors from the comfort of indoors with this Digital Indoor-Outdoor Thermometer with Alarm.
With a remote sensor on a 9ft flexible lead place this outside a window, allowing the lead in through the window. You can then see on the digital screen both the outdoor and indoor temperatures at the same time.
This thermometer also has a programmable, audible high / low alarm which you can use with the remote sensor so you are alerted to a change in temperature.
Perfect for use outdoors as well as indoors, our best selling thermometer is this Digital Max Min Thermometer. Easy to read and easy to use it has a large digital which shows at the same time:
the maximum temperature achieved
Can You Predict Frost Damage ?
Although you cannot predict frost damage, you can predict frost - and as a result provide your plants with protection so they don't get damaged!
You can read how on the Met Office website by clicking here
Or read our summary below.
So for a simple method to follow to predict frost you’ll need to be able to mount a thermometer outside, 4ft / 1.25m above the ground, facing northeast and in the shade.
Take a temperature reading at 2.00pm.
Take a further temperature reading at 7pm.
Now comes the maths . . .
Double the temperature taken at 7pm and then subtract the 2pm reading. This should then give you a predicted temperature for the following dawn!!
For example, you took a reading at 2.00pm of 14 degrees Celsius and a reading at 7pm of 8 degrees Celsius, your calculation would be (8 x 2) 16 minus 14 so a predicted dawn temperature of 2 degrees Celsius.
The calculation above is to predict air temperature – you’ll find that ground temperature will be several degrees lower.
A Few Simple Ways To Provide Frost Protection
So if you’ve predicted that there is likely to be frost, there are a few quick and easy to install products which will help to protect your plants outside in your garden. Here are just a few examples.
The simplest way to protect your plants is to cover them with a garden fleece.
This Cosygrow Fleece is 2 metres wide and you can order as many metres as you require. It's easy to cut with scissors, is hand washable, tear resistant and UV stabilised so can be used successfully for several seasons.
Another option for providing instant frost protection is these Easy Fleece Jackets.
What makes these Easy Fleece Jackets so great is that they incorporate an internal drawstring around the base - so you simply place them over your chosen plant / plants and secure with the drawstring. It's that simple!
These fleece jackets are also a natural green colour making them unobtrusive in your garden.
Bell Cloches are an easy and attractive way to protect individual plants from the worst of the weather.
Available in a range of sizes you can purchase traditional glass bell cloches or modern, plastic bell cloches made form clear plastic and featuring an adjustable air vent in the top.
The weight of the glass bells will keep them securely in place which galvanised steel pegs can be purchased to anchor the plastic cloches securely to the ground.
Bell cloches are a good way of protecting plants as their shape captures maximum light and also directs rain and condensation into the surrounding soil.