I want marrows by the barrow-full…

How can I ensure the best yield from my marrows? Daniel Martin, London DAVID: In this heat, the most important thing for marrows and other cropping vegetables is a steady water supply. It will help stop marrows splitting.

Feed plants weekly with a high-potash liquid (such as tomato feed) to help them produce strong vegetables – and pick mature fruit regularly to keep the plant producing right through to October.

A common garden pest, slugs have been around in the UK since the end of the last ice age.

As a nocturnal species prone to drying out, slugs spend most of their lives underground. They only venture out in the cool and wet – which is why we see hundreds of their silver trails the morning after a cold rainy night.

As we all know, slugs love to eat plants, causing an estimated £8million of crop damage a year in the UK.

One way to protect your garden is with “sacrificial” flowerbeds to tempt slugs away from your prized blooms.

Nasturtium, hostas, petunias, dahlia and delphiniums all work well.

Or just fill your garden with plants slugs dislike. These include ones with tough leaves they find hard to chew (geraniums or ferns) or those that taste bitter (spurges or foxgloves).

For more top tips on slug control, see my website, daviddomoney.com. garden soil can contain as many as a million of them.

Common microbes in gardens include bacteria, algae and fungus.

Microbes are essential to the health of our gardens. They eat dead creatures, animal waste and decaying plant matter – and put the nutrients