Why Do Strawberry Leaves Turn Red?

As a strawberry lover, nothing makes me happier than walking out to my garden and seeing big vibrant red strawberries nestled in deep green leaves. However it can be alarming when those green leaves suddenly start changing color. If you’ve noticed red pigmentation on your strawberry foliage, you likely have some questions. In this article, we’ll explore the most common reasons behind red strawberry leaves so you can get your plants back to their beautiful, productive selves.

What Causes Red Leaves on Strawberry Plants?

There are a few key factors that can cause the leaves of strawberry plants to turn red or purplish:

• Cold Temperatures – Cold snaps or frost can shock strawberry plants especially young ones and trigger red pigments in the leaves. This acts as a signal to the plant that winter is coming.

• Leaf Scorch – A fungal disease causes lesions that spread, turning leaves red and purplish. Wet, cool weather promotes infections.

• Leaf Spot – Another fungal culprit, leaf spot creates small, round dead spots on leaves that can merge and kill leaves. Common in spring.

• Soil pH – Strawberries prefer slightly acidic soil between 5.5-6.5. Too high or low pH disturbs nutrient availability.

• Nutrient Deficiencies – Lack of nitrogen or phosphorus can cause red pigments in old or new leaves.

• Seasonal Changes – Red leaves in fall can be natural as the plant prepares for winter dormancy.

Pay attention to patterns and timing of reddening to identify the cause. We’ll explore these factors in more detail next.

Cold Temperatures

Strawberry plants are hardy down to zone 2, but sudden cold snaps can still shock them. Young plants and new transplants are most susceptible. When hit with frost or plunging temperatures, strawberries will start to shut down and prepare for winter by producing anthocyanins that redden the leaves. This is the plant’s natural mechanism for pulling nutrients and energy from the leaves back into the roots.

If you notice red leaves after a cold spell, protect plants with row cover and wait it out if temperatures are expected to rise again. This reddening doesn’t necessarily harm yields unless the cold seriously damages flowers and fruits. Just keep an eye out for other issues that stress could aggravate.

Leaf Scorch

With its spotty, “scorched” lesions, leaf scorch is easy to identify. The fungal disease Diplocarpon earlianum manifests as small purplish dots that gradually spread and fuse, creating irregular blotchy patches. As the infection worsens, leaves crispy, dry and turn fully red or brown before dying.

Leaf scorch thrives in cool, wet conditions often seen in spring and fall. While it looks bad, it typically won’t decimate yields if caught early before defoliation occurs. Promote airflow through plants, space correctly, and remove any infected leaves immediately. Apply neem oil spray as a preventative when wet weather is forecast.

Leaf Spot

The fungus Mycosphaerella fragariae causes frustrating leaf spot, especially on older strawberry plants. Look for characteristic small, dark red spots, about 1⁄8-1⁄4 inch big. As the fungal infection progresses, the centers turn tan or white. Eventually whole leaves can die.

These spots often first emerge during spring’s wet weather. The spores spread readily via wind, rain splashes, and overwintered debris. Keep the garden free of dead leaves, stake plants for airflow, and use drip irrigation to prevent spores. Consider rotating annual varieties if leaf spot plagues perennial beds.

Soil pH Imbalance

As native forest plants, strawberries thrive in acidic soils, ideally between 5.5-6.5 pH. Too far below or above this range causes nutrient deficiencies that show up as red foliage. For example, anthocyanins in leaves often increase in acidic conditions as phosphorus becomes less available.

Use a soil test to determine your garden’s pH. To lower pH, amend soil with elemental sulfur or acidic organic matter like pine needles. To raise pH, add limestone, wood ash, or crushed eggshells. Reaching the ideal acidity makes nutrients like nitrogen and phosphorus accessible.

Nutrient Deficiency

Lack of macronutrients nitrogen (N) and phosphorus (P) also manifests as red leaves. Phosphorus deficiency typically first appears as red leaf margins and tips. Nitrogen deficiency starts as yellowing leaves that turn red. Both deprive plants of crucial compounds needed to photosynthesize and grow.

This often results from incorrect soil pH but can also derive from overworked soil that needs amending. Fertilize with manure, compost, bone/blood meal for phosphorus, and feather meal/alfalfa for nitrogen. Fish emulsion makes a great liquid fertilizer too.

Natural Seasonal Changes

Seeing red or purple leaves in your strawberry patch in autumn isn’t necessarily bad news. As daylight wanes, strawberry plants begin to shut down for winter dormancy. The red pigments help the plant pull nutrients out of the leaves safely and store food in the roots and crowns.

Allow plants to follow their natural cycle. Once leaves fully brown and die back, trim them to tidy up beds. Add a thick layer of straw mulch and let plants rest until next spring’s growth. The old leaves will give way to a fresh green canopy when growing conditions improve.

How to Fix and Prevent Red Leaves

While usually not fatal, consistently red strawberry leaves can affect plant vigor and fruit production. Use these tips to troubleshoot the cause and get your plants back to their healthy, productive state:

• Monitor for patterns like leaf spots, margins vs interiors, etc. to identify causes.

• Protect young plants if cold snaps occur with floating row cover.

• Improve airflow and reduce wetness to prevent fungal disease.

• Test and amend soil to reach ideal 5.5-6.5 acidity.

• Fertilize with compost and organic nitrogen/phosphorus sources.

• Use preventative neem oil applications when disease risk is high.

• Consider rotating annual strawberry varieties susceptible to leaf spot.

• Let plants complete their lifecycle and go dormant naturally in fall.

When to Worry About Red Leaves

Mild to moderate red leaf symptoms are mostly an aesthetic nuisance rather than major production problem for strawberries. However, severe cases left unaddressed can impact plant health and fruit yields.

Here are signs that red leaves require more urgent attention:

• Sudden leaf color change not associated with seasonal shifts
• Lesions spreading rapidly or whole leaves dying
• Multiple leaves reddening at once
• Newly planted or young plants affected
• Days to weeks of symptoms without improvement

At the first signs of anything more than transient leaf reddening, spring into action with mitigation measures. Knowing the root cause is key to reversing the damage so your strawberries can thrive!

Frequently Asked Questions

Why are my strawberry leaves turning red after transplanting?

Newly planted strawberries often react to environmental changes. Their leaves may redden due to transplant shock, temperature fluctuations, or overly wet or dry soil. Ease the transition by hardening off plants, protecting from frost, amending soil, and providing even moisture.

Should I remove red strawberry leaves?

It’s best to prune off leaves exhibiting fungal disease symptoms to prevent spreading spores. But if leaves are reddening due to natural fall dormancy or nutrient issues, leave them be until fully dead. The plant reclaims some nutrients from dying foliage.

How do I fix red strawberry leaves from cold?

For young or vulnerable plants, prevent cold damage by covering with fabric row cover overnight when frost threatens. Remove covers daily to avoid overheating plants. There’s no fix for leaves damaged by freezing, but the plant should recover once temperatures warm.

What nutrient deficiency causes red strawberry leaves?

Both nitrogen and phosphorus deficiencies can cause red pigments in old or new leaves. Test soil pH and amend accordingly, then fertilize with organic nitrogen and phosphorus sources like compost, manure, bone/blood meal, etc.

Is it normal for strawberry leaves to turn red in fall?

Yes! Red leaves in autumn are part of the natural seasonal cycle as the plant prepares for dormancy. The red pigments help the strawberry safely reabsorb nutrients from the leaves to store energy in its roots over winter.

Can too much rain cause strawberry leaf scorch?

Absolutely. The fungal disease thrives in wet, humid conditions. Prevent splashing of spores by avoiding overhead irrigation. Promote airflow through the foliage. Remove any infected leaves immediately before the disease spreads.