Summer is progressing
This is often one of the hottest months of the year. July can be a dry month, though still prone to brief summer showers and unsettled periods. It is wise to collect rain water in butts, and to use your bath, shower and washing-up water for garden irrigation.
While the grass may not be growing as fast as it did in June, weeds will still spread unless checked. Pests and diseases thrive in the warmth - biological controls can be a viable option in the suitably warm conditions.
Summer is most advanced in the southern part of the country, particularly inland in the Home Counties. Coastal areas are slightly cooler. The north and west of England are, as often, cooler and wetter.
Temperature
Some of the hottest days of previous years have been in July. The afternoon temperatures in the south of England can reach 29-32°C, while in the north and west, and in Wales, Scotland, and Northern Ireland, they can reach 27°C. The Highlands may only reach 24°C, and coastal regions in the South of England may not reach above 27°C.
The risk of frost is now extremely low, but not impossible. Gardeners in cold areas can plant out bedding and seedlings, but are still advised to keep an eye on the local forecasts.
Ventilation and shading should be considered in the greenhouse and conservatory, especially on clear days when the heat of the sun is unimpeded by cloud. Clear days will also see the most water evaporation from soil and ponds, and the most uptake of water by plants.
Rain
Southern and central areas of the UK rarely receive enough rainfall to meet the needs of plants this month. Seedlings, pot plants, and new plants or lawns are particularly vulnerable to drought.
Northern and western areas may receive enough average rainfall over the month, but watering will still be necessary in prolonged sunny or dry spells. Rainfall can vary significantly on a local basis.
The south-west of England usually receives more rain than the south or south-east.
The average rainfall in England is usually 40–50mm in the south (1.75-2in) and 60-65mm (2.25-2.75in), in the north. This compares to 80-85mm (3.75in) for Wales, and 90-100mm (3.75-4in) for the whole of Scotland, although there are local variations.
There are often brief summer showers in July, sometimes heavy and thundery. Freak hailstorms have even been reported. But this short, sharp fall of water will run off and evaporate quickly, without being absorbed into the soil. Do not assume that brief rainfall will make it unnecessary to water the garden.
Wind
Hot, sunny July days are usually accompanied by light south-westerly or westerly winds. Inland conditions can be quite still. Sea breezes may provide a welcome relief in coastal regions. Gales are infrequent, but do occur in the north-west of England and the North of Scotland, particularly in the Western Isles.
It is a good idea to ensure plants are well staked, even during still periods, as showers and brief gusts can be enough to damage stems.
Light
Light levels are good in July, although not as high as in June, as we are past the summer solstice. The north and west of England receive on average about 160-165 hours of sunshine, and the south, south-east, and south-west get about 175-180 hours.