The weather has been cooler this year with periods of rain and lack of long periods of full sun. These conditions are fantastic for cool loving vegetables like lettuce, carrots, parsnips, spinach. Lack of sunshine is not liked by courgettes, pumpkins or squash.

How do I tell if my Vegetable Plant is feeling stressed?

There are a few signs to look out for if your plants are feeling stressed.

1. Yellowing Leaves

This is a big problem this year. My courgettes and pumpkins are both showing these symptoms in June, after I planted them out into the raised beds. I believe it is because we haven’t had enough sun or heat and it’s been too cold.

Solutions:

1. Try feeding courgettes, squash and pumpkins with Tomato liquid feed. It contains lots of nitrogen, to see if they need more nutrients. They will recover the week after you feed the soil.

2. Add compost to the top of the soil around the stem of the plant and water in. The water will push the nutrients into the soil. This is a great fix if you haven’t got any liquid feed handy.

3. Make sure they have enough water once planted out in a raised bed.

4. Unfortunately other than timing (I.e. when is the best time to plant outside). There is nothing you can do about it being too cold or not enough heat and sun. Read my article: Vegetable Growing is a game of Strategy & Risk

2. Wilting or drooping Leaves

My sweet peppers always suffer from dropping leaves in the summer heat. When the temperature is too high, plants are stressed. When they do not have enough water, they close the pores on the leaves to stop water evaporation so they can survive on limited water.

The plant goes into survival mode and the leaves droop or wilt because there is not enough energy in the plant to hold them up.

This also affects the crop, your harvest of vegetables will be smaller and limited whilst the plant tries to survive through the stressful period.

3. Heat Stress

Heat Waves will stress your vegetable plants as they are periods of consistently high temperatures. Your cool loving plants will suffer with the following symptoms.

a) Heat stress symptoms for Cool Loving Vegetables.

When temperatures are over 25 degrees centigrade, cool loving plants become stressed.

Bolt or Bolting (flowering plant)

When there is a rise in temperature, a vegetable plant becomes stressed and it goes into survival mode. It stops growing the vegetable, starts flowering (it normally sends up a flower spike) and runs to seed.

This can be very frustrating for vegetable growers, when they have nurtured the vegetable to the almost harvest stage and then the plant bolts.

Solution – Can I Stop a Plant from Bolting?

Yes, try out the following solutions, to see what works for you in your vegetable garden:

• Put 30% shading material over your cool loving vegetables like lettuce. This reduces the temperature of the vegetable plant.
• Grow bolt resistant varieties, like ‘Romaine’ lettuce or ‘boltardy’ beetroot.
• Try growing some shade loving vegetables to reduce the chance of bolting. Radishes & loose leaf lettuce can be grow in the shade.
• Don’t let the soil dry out around cauliflower, spinach, lettuce, rocket and radishes as this will trigger the bolting process faster. Water well in hot weather.
• Harvest the vegetable at the right time. If your radishes are ready, harvest them. If you keep them in the ground for more than 4 weeks, they will be into the bolting period. Lettuce also needs frequent harvesting by pulling off a few leaves daily. Bolting vegetables will taste bitter as they are past their best flavour.

b) Heat stress symptoms for Warm loving vegetables

Even warm loving vegetables get stressed when the temperature is over 32 degrees centigrade.

Here are some of the plant stressed symptoms of Warm loving vegetable plants:

• Wilting or drooping leaves,
• Scorch marks (areas of black and dark brown),
• Yellow leaves.

Solutions

1. Give the plants a very good water at the end of the day when the temperatures have reduced so there’s no evaporation from the soil surface and the plant gets all the water available. Over night they should recover from the drooping leaves. Put them in a less hot spot the greenhouse for the next day to help them recover or consider putting up 30% shading on the greenhouse.

2. Mulch the soil surface with multipurpose compost. Then water in the nutrients so that the moisture stays in the soil and the nutrients go down to the roots.

3. Scorched leaves can be prevented by removing the leaves from touching the glass and having a shading material between the leaf and the glass.

4. Leaf Curl

Leaf Curl almost always indicates that a pest is involved.

The pest will attack the leaves and they will curl in a response to their stress. My Apple tree leaves in the photo have been attacked by whitefly, green and blackfly.

Solutions:

Take a good look at the plant, uncurl the leaves and see if there are any pests.

• See if you have any spiders or ladybirds on the plant, these are your natural defences, they will be eating the greenfly.
• Squish the greenfly off the leaves or blast them off the leaves with water from a hosepipe.
• Don’t use chemicals as they will kill the friendly wildlife.

More Reading:

• How to deal with Blackfly, Greenfly and aphids
• Nature does it best’ Pest Control in the Vegetable Garden

5. Sun Scorch

Plants can get burned in the greenhouse as the sun’s rays bounce off the glass and scorch the leaves.

Solutions

• Remove the leaves from the glass and add shading netting to your greenhouse to reduce the direct sunlight.
• If the plant is in a pot, remove it from the hot area and put it in a semi shaded position whist it recovers.

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The Techniques Series

The importance of potting on from a small pot to a large pot.

How to Plan your Vegetable Garden

Space saving in the Vegetable Garden – Intercropping.

5 Symptoms of Stressed Vegetable Plants with Solutions

Growing Vegetables is like a Game of Strategy and Risk

The Little Things, Impact The Most – Looking After Your Vegetable Garden – Weeds & Mulch

How To Store and Organise Vegetable Seeds