Factor in water droughts and hosepipe bans, and suddenly you’re facing potential gardening disasters. As it turns out, there’s a surprisingly simple method that takes little time and effort to help you properly decide which plants need watering immediately, and which ones you can perhaps spare for a while – and all you need is a pencil. This can ensure that your outdoor plants or your houseplants survive the latest heatwave without using excessive amounts of water. While you can also perform the same trick with your finger, when the soil is too compact, a pencil will be easier to insert. Some plants, such as succulents and cacti, thrive when they’re on the dry side, so the pencil trick wouldn’t apply.