Stay on top of the crops to keep them healthy in the heatwave

THE key to producing a bountiful supply of fruit and vegetables throughout the year is to understand how different crops grow and respond to varying seasonal conditions. At the kitchen garden here at RHS Garden Harlow Carr, we’re working hard to keep the plants healthy, growing well and - especially with the current heatwave - well-watered.

Over the past month we have been watering the fruit and vegetable beds constantly, along with newly-planted perennials around the garden. The best time to water is early in the morning; this helps to avoid evaporation loss during the day. It may also be necessary to water on an evening too, depending on conditions. Vegetables need regular watering with just the right amount of water to encourage the healthiest and most productive crops.

A couple of weeks ago at our annual flower show, our local garden advisor Martin Fish and myself ran a series of talks and demonstrations about growing fruit and vegetables. We also had gardeners’ question time sessions which drew in many visitors who were keen to get answers to their burning horticultural questions. Below are some of the most frequently asked questions – together with the answers, of course - which I thought would be worth sharing with you:

Why are my courgettes rotting at the end?

This could be down to poor pollination in colder conditions which can mean courgettes fail to develop properly, causing them to quickly rot on the plant. As we now have warmer weather, more insects are able to pollinate. If your courgettes continue to rot, it may be advisable to pollinate by hand by using a small paint brush to transfer pollen between the courgette flowers.

I’ve noticed the leaves on my tomatoes are curling. What can I do to prevent this?

Leaf curl is a common complaint on tomatoes and is usually caused by a fluctuation in temperatures. During early summer in particular, the nights can still be relatively cold in comparison to the warmer days. This can cause the leaves to curl as the plants are unable to cope with the accumulation of carbohydrates that occurs on cold nights. This is nothing to be concerned about as it won’t affect the fruit. Aphid attacks are also a common cause of leaf curl. Aphids often colonise on the under-side of the leaves. Suggested treatment includes using biological controls in a glass house.

How do I control slugs on my vegetable plot?

At RHS Garden Harlow Carr we control our slug population organically. We use a biological control called Nemaslug. Nemaslug helps to control all common species of small-to-medium sized slugs. One application contains 300.000 nematodes for every square metre of soil, and lasts up to six weeks. Ferric phosphate slug pellets are also an organic way to control the slug population in the kitchen garden.

When do I prune my established espalier apple trees?

Trained fruits, such as apples and pears that bear short fruiting spurs, should be pruned annually as the growth slows down normally around August and September. Renovation pruning is carried out in the winter (November to March) along with spur thinning. More information can be found on the RHS website which offers a step-by-step guide on how it should be carried out. Alternatively, why not come down to RHS Garden Harlow Carr to see how it is done and get some advice for your own garden? There’s always someone on hand and happy to help.