Rain
Widespread bursts of rain, or ‘April showers’, are common this month. But do not be deceived by sudden bursts of rainfall.
You may need to start watering vulnerable plants such as seedbeds and new plantings during dry, bright and windy spells which may feature during this month.
If you need to dry out your soil further before sowing seed outside, then you can speed up the natural drying process by about two weeks, by lightly cultivating the soil. Covering it with fleece, cloches, or plastic, will warm the ground, improving the germination of seed crops like carrots.
Heavy rain showers and melting snow, which are still common in some districts, will continue to wash nutrients out of the soil. These will need replacing by applying fertiliser.
Sunshine
The days are now much longer, with light levels averaging out at three quarters of the maximum summer levels. However, in northern districts, and when there is substantial cloud cover, light levels may be lower, and plant growth not as strong.
Most areas can expect around 150 hours of sunshine, ranging from about 120 hours in a dull year to about 190 hours in a sunny year.
Remember to ventilate the greenhouse or conservatory during the warmest part of the day, to prevent the sunshine scorching the leaves of your plants.
Consider applying shade paint to the glasshouse panes, to protect them from the stronger sunshine at this time of year. Shade netting is an alternative, and newspaper is the cheapest option.
Temperature
With longer days and stronger sunshine, growing conditions are now improving. If a sudden cold spell is forecast, protect tender plants and new shoots with a double layer of horticultural fleece. Unfortunately, Magnolia flowers can often become browned, and Acer leaves scorched by April frosts.
Continue to check your conservatory and greenhouse heaters, to make sure they are working properly (a maximum-minimum thermometer is useful for monitoring). In many cases, one frost could kill an unprotected tender glasshouse plant.
Wind
Generally the wind eases off this month, but thunderstorms can bring short spells of gusty weather.
North and north-westerly winds can still bring snow, but southerlies will bring warmer days with a hint of summer.