Strawberries are one of the most rewarding plants to grow. Not only do they taste delicious, but seeing bright red fruit on a background of vibrant green leaves is sure to make any day better. That is why the appearance of red leaves can raise questions and concerns about the health of your plants and the potential implications. So, what causes red leaves on strawberry plants and are they a problem?
What causes red leaves?
- Natural ripening process: One common cause of red leaves on strawberry plants is the natural ripening process. As strawberries mature and approach readiness for harvest, the leaves closest to the fruit might begin to turn red. This can be a sign that the plant is preparing to yield ripe berries. Similarly, as we reach the end of the season, leaves may turn red as the plant starts to go dormant for the winter.
- Nutrient deficiencies: Imbalances in essential nutrients like nitrogen, phosphorus, or potassium can affect leaf colour. A deficiency in nutrients required for chlorophyll production might cause leaves to turn red.
- Stress factors: Environmental stressors, such as extreme temperatures, drought, or excessive sunlight, can lead to the reddening of strawberry leaves. Stress can disrupt the plant's normal physiological processes, causing changes in leaf colour.
- Excessive exposure to direct sunlight can lead to the production of anthocyanins as a form of protection against sunburn and damage from UV rays. This is more likely to occur in young leaves that are still developing their protective mechanisms. To help prevent this, ensure that your strawberries are given some shade, particularly in extreme summer heat.
- A lack of water will prevent any plant from taking up nutrients, and strawberries are no different. If you find that you have loose soil or your soil dries out too quickly, adding organic matter such as compost or manure can quickly help with water retention issues.
- Soil pH: Strawberries like their soil to be slightly acidic. If they are grown in soil that is too alkaline, it can hinder the plants’ absorption of essential nutrients. This then creates a nutrient deficiency which, as previously discussed, can cause the leaves to turn red. To lower the pH of your soil, add a small amount of sulphur or sulphate of iron.
- Pests & diseases: Infestations of pests like aphids or diseases like common leaf spot can lead to the discolouration and reddening of leaves. These issues can interfere with the plant's ability to photosynthesise properly. Leaf spot is usually not a huge issue for your plant, and is mostly aesthetic, unless it starts to lose a large amount of leaves. Unfortunately, there is no perfect way to prevent leaf spot as it can be spread through the wind or rain, and because plants can carry the disease before any symptoms are shown. All you can do is minimise the risk by removing any heavily infected plants; ensuring that your growing area is clean, has sufficient airflow, and is free from weeds and dead leaves; and avoiding watering from above.
Are red leaves an issue?
The presence of red leaves on strawberry plants is not always indicative of a severe problem. It's essential to assess the broader context, including the extent of reddening and the overall health of the plant. In some cases, natural ripening or temporary stress might lead to reddish leaves without significant harm to the plant's well-being. However, prolonged stress, nutrient deficiencies, pests, or diseases can have negative implications for the plant's growth, yield, and overall vitality.
Prevention & management:
- Proper watering: Maintain consistent and appropriate watering practices to prevent drought stress and poor nutrient uptake. Ensure the soil is well-draining but retains moisture.
- Sun protection: Provide shade or protection during intense sunlight to prevent sunburn and excessive stress on the plant.
- Nutrient management: Regularly fertilise the plants with a balanced, appropriate fertiliser to prevent nutrient imbalances - preferably organic fertilisers as these are less likely to burn your plants than synthetic fertilisers. Conduct soil tests to determine the specific nutrient needs.
- Pest & disease control: Regularly inspect plants for signs of pests or diseases. Implement proper pest management practices, such as introducing beneficial insects or using organic solutions.
- Adequate spacing: Plant strawberries with adequate spacing (about 30cm apart) to allow for proper air circulation and reduce the risk of disease.
- Mulching: Apply a layer of organic mulch around the plants to help retain moisture and maintain stable soil temperatures.
- Regular pruning: Remove any damaged or diseased leaves promptly to improve airflow and prevent the spread of issues.
The bottom line:
Red leaves on strawberry plants can result from a variety of factors, ranging from natural ripening to stress, nutrient imbalances, pests, and diseases. While not always a severe problem, it is important to assess the situation comprehensively and take appropriate measures to prevent or manage the underlying causes. By implementing proper care practices, including proper watering, nutrient management, and vigilance against pests and diseases, strawberry growers can maintain healthy plants and maximise fruit yield.
