Why Are Strawberry Plant Leaves Turning Red?

Strawberries are a delightful and rewarding fruit to grow in your garden. The sight of vibrant red berries against a backdrop of lush green foliage is both beautiful and mouthwatering. However, if you notice that the leaves of your strawberry plants are turning red, it may be a cause for concern. In this article, we will explore the possible reasons behind this phenomenon and provide solutions to help you address the issue.

The Long Answer

The sight of red, maroon, or purple strawberry leaves can be quite alarming. While it’s normal for strawberry plants to change leaf colors in the fall as they prepare for dormancy, red leaves appearing earlier in the growing season may indicate an underlying problem that needs attention.

To identify the cause of red leaves, it is important to carefully monitor your plants and engage in a process of elimination. Let’s delve into some potential reasons for this issue.

Cold Temperatures

Premature cold snaps, especially late spring frosts, can shock strawberry plants and cause their leaves to turn red. This is especially true for young plants and those that were recently transplanted. In cooler spring weather, as well as instances of transplant shock, reddening leaves may be observed in new plantings. On the other hand, mature plants may naturally shed their oldest lower leaves to make way for new growth.

If the reddening is limited to old lower leaves or occurs during early winter, and the weather has been consistently warm, it is unlikely to be solely related to cold temperatures. In such cases, where the red pigment is confined to specific areas or margins of the leaves, it is likely that another issue is at play.

To protect your plants from upcoming cold weather, consider using row covers. For newly planted crowns, additional warmth in the spring can be provided by covering them. If it is fall, allow your plants to go through their natural cycles. To prevent strawberry disease issues, remove leaves once they have fully withered and turned brown.

Leaf Scorch

If the redness on your strawberry leaves appears as speckles, dots, or splotches, leaf scorch may be the culprit. This condition is caused by the fungus Diplocarpon earlianum and results in red and purple lesions on the leaves. Leaf scorch tends to be more common in wetter and cooler weather, especially during the early spring or late fall.

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The symptoms of leaf scorch include initial purplish-brown speckles and dots that resemble “tar drops.” There is no defined border around these spots, and they gradually merge to form bright red or purple lesions. Leaves may dry up, turn brown, and curl at the edges, giving them a scorched appearance.

While leaf scorch can look unsightly, it typically does not significantly affect fruit yields unless the infection is severe. To prevent its spread, promptly remove infected leaves and debris. Applying a neem spray preventatively every 1-2 weeks can also be helpful.

If you live in a humid area prone to fungal infections, consider choosing leaf scorch-resistant strawberry varieties such as ‘Hood,’ ‘Rainier,’ or ‘Seascape.’ Additionally, make sure to provide adequate spacing and airflow between plants.

Leaf Spot

Leaf spot is a common problem in perennial strawberry plantings, often occurring during extended wet periods in late spring. This condition is caused by the fungus Mycospharella fragariae, which spreads through spores carried by the wind or via overwintered dead foliage.

While there are no known cures for this strawberry disease, it is generally an aesthetic issue that does not cause major problems unless a significant number of leaves are lost. To minimize the impact of leaf spot, maintain a clean strawberry planting by regularly removing debris and preventing dead leaves from overwintering in the garden.

In the fall, mow dead plants after they finish fruiting to encourage new growth. Avoid overhead irrigation, as this can contribute to the spread of leaf spot. Another preventive measure is to grow day-neutral strawberries as annuals and rotate their location in your garden. Consider using resistant varieties such as ‘Ogallala,’ ‘Ozark Beauty,’ or ‘Earliglow.’

Wrong Soil pH

Strawberries prefer slightly acidic soil, as they naturally thrive in the pine needle duff of coniferous forests. When the soil becomes too acidic or too alkaline, strawberries may exhibit signs of distress, including red leaves.

It is important to note that soil acidity varies based on climatic conditions and geographical regions. Cold, wet climates tend to have more acidic soil, while hot and dry regions often have alkaline soil. However, these are generalizations, and it is crucial to conduct a soil test to determine the specific conditions of your garden.

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To address soil pH issues, start by testing your soil. Once you have the results, make the necessary amendments to your strawberry beds:

  • If your soil is acidic, use materials such as limestone, dolomite lime, wood ash, bone meal, ground eggshells, or oystershell to raise the pH and make the soil more alkaline.
  • If your soil is alkaline, lower the pH by incorporating sulfur, peat moss, cottonseed meal, or mulching with pine needles and straw.
  • Compost, which generally has a neutral pH, can benefit strawberry plants regardless of the soil type.

Phosphorus Deficiency

If your soil’s pH is out of balance, you may also face a phosphorus deficiency in your strawberry plants. Phosphorus becomes less available to plants in soils that are excessively acidic (pH below 5.5) or overly alkaline (pH above 7.0). This deficiency is characterized by red leaf tips, as if the edges of the leaves have been dipped in red paint.

To address this issue, adjust your soil pH to the ideal range for strawberries, which is between 5.5 and 6.9. Once you have done this, amend the soil with a phosphorus-rich fertilizer. Some options include manure-based compost, blood meal, bone meal, fish bone meal, mineral rock dust, and rock phosphate.

Nitrogen Deficiency

Nitrogen-deficient soil can also cause strawberry leaves to turn red. Nitrogen is a vital nutrient for healthy growth and fruiting in strawberry plants, requiring significant fertility to produce delicious fruits throughout the summer.

Differentiating nitrogen deficiency from phosphorus deficiency is possible by observing the color of the leaves. Strawberry plants lacking nitrogen will exhibit yellowing leaves before they turn red. Unlike diseases, the discoloration will not appear spotty or infected. Instead, it may appear as though the entire leaf is affected.

Applying diluted fish emulsion weekly during the flowering and fruiting period is an effective way to ensure that your strawberry plants receive sufficient nitrogen. During the spring leaf phase, avoid excessive nitrogen application, as this can result in excessive foliage growth instead of increased berry production. Instead, use a slow-release organic fertilizer, such as high-quality compost or an all-purpose blend, at the time of planting.

End of the Growing Season

Towards the end of the growing season, it is natural for strawberry plants to exhibit red leaves. Similar to autumn trees, strawberry plants produce anthocyanins from accumulated sugars. These compounds create a red pigment in the leaves as the plant redirects nutrients from the leaves to store them in the roots over the winter.

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If your strawberry leaves turn red in the fall, there is no cause for concern. Allow your plants to complete their natural lifecycle. After the first hard freeze, remove dead debris and provide a generous layer of straw mulch to insulate the crowns throughout winter. In the spring, you can expect a fresh flush of green growth.

Frequently Asked Questions

Q: Why are the leaves of my strawberry plants turning red?
A: Red leaves in strawberry plants can be attributed to various factors such as cold temperatures, leaf scorch, leaf spot, incorrect soil pH, phosphorus deficiency, nitrogen deficiency, or the natural end of the growing season.

Q: How can I prevent red leaves in my strawberry plants?
A: Red leaves can be prevented by taking appropriate measures for each specific cause. These include protecting plants from cold weather, removing infected leaves and debris for diseases, adjusting soil pH, and addressing nutrient deficiencies.

Q: Can red leaves on strawberry plants be harmful?
A: While red leaves may indicate underlying issues or diseases, they do not necessarily harm the plants or significantly affect fruit yields. However, prompt attention and appropriate measures are important to maintain the overall health and productivity of your strawberry plants.

Q: Should I be worried if strawberry leaves turn red in the fall?
A: No, it is natural for strawberry leaves to turn red in the fall as the plant enters its dormant phase. This is part of the plant’s life cycle, and it is advisable to let it progress naturally.

Q: What are some strawberry varieties that are resistant to diseases?
A: Certain strawberry varieties, such as ‘Hood,’ ‘Rainier,’ and ‘Seascape,’ are known for their resistance to diseases like leaf scorch. Consider selecting these varieties if you live in a humid area prone to fungal infections.

Strawberry plants turning red can be a cause for concern, but understanding the various factors that contribute to this issue can help you address it effectively. By carefully monitoring your plants and employing the appropriate solutions, you can maintain the health and vitality of your strawberry garden. Remember to protect your plants from cold temperatures, address diseases promptly, adjust soil pH as needed, and provide adequate nutrition. With proper care, you can enjoy a bountiful harvest of delicious strawberries year after year.

Ames Farm Center