Frost Zones


A problem gardeners throughout the UK have had to put up with for years is; "When is it safe to sow and/or plant out in the open"?

When the Media and Garden Press give advice on frosts there is generally little or no comment on how this advice should be adjusted to suit our geographical position in the UK.

If information is forthcoming, it generally takes the form of; "People further north should sow a bit later"

To illustrate how far further is, and how long is a bit is, I have produced this chart to allow you to make a mental + / - adjustment to the timing of events in the attached web pages to suit your own situation.

To do this you require only two pieces of information and they are;

The writers planting out date, which is Week 21, and your planting out date.


Step 1:

Look at the chart you will see that someone living in the London area (17) is around four weeks in front of the writer, and conversely someone living in the Edinburgh area (23) is around two weeks behind.

Step 2:

Lets say a particular task was indicated on the web page as being scheduled to be done in say Week 12, then people in the London area might well be able to do that task around Week 8 or 9, whereas people in Edinburgh would be wiser to wait until Week 14.

Step 3:

To establish your planting out date, locate where you live on the map, and note the grid value, then adjust your date + / - to Week 21.

Please note, each grid is approx 50 miles x 50 miles (2500 sq.miles) meaning that people within the same grid could experience different weather situations for a number of reasons e.g. their garden layout, light, shade, wind, frost pockets, altitude and sea air etc.

When using this chart and the timings given on this web site; "Let common sense prevail"

In the event that people with actual knowledge of the latest frosts find that the grid value is different they should adjust their grid value accordingly when using the data in this website.

Failing that and you are new to gardening, and don't know how much to adjust my figures by, then I would suggest you have a chat with experienced gardeners in your area as to when they carry out certain tasks, then make the necessary adjustment.

A few words of advice would be;

Only carry out the tasks at the said times if conditions allow.

If conditions are not deemed suitable, wait until they are.

Similarly, delay your timings, if you find you are short of frost free space to store your seedlings until planting out time.

This Met Office link should give you more precise information on expected weather conditions in your are.

Finally, patience is said to be a virtue, and due to the sometimes fickle British weather you may be required to be very virtuous.

But do not despair plants have an amazing ability to catch up on lost time.

This "link" can be adjusted to give you weather forecasts specific to your location.

Related links;

Frost and Frost Pockets, Plant Hardiness.

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