Blueberry Leaves Turning Purple

If you’ve noticed your blueberry leaves turning purple, you’re right to be concerned. This color change is a classic signal from your plant, and it often points directly to a nutrient deficiency. While it can sometimes be related to cool fall weather, seeing purple leaves in the growing season means your bush needs help. Let’s look at why this happens and, most importantly, how you can fix it.

This specific symptom is your blueberry’s way of crying out for attention. The purple hue usually starts on the edges of older leaves and can spread inward. It’s different from the uniform, vibrant red or purple you see in autumn. During spring and summer, it’s a strong indicator that a key nutrient is missing from the soil.

Primary Suspect: Phosphorus Deficiency

In most cases, purple leaves on a blueberry bush mean a lack of phosphorus. Phosphorus is vital for energy transfer and root development. Without enough, the plant can’t properly produce or use sugars, leading to a buildup of anthocyanin pigments—that’s what causes the purple color.

Here are the signs that point to phosphorus being the problem:

Purple or reddish-purple coloration on older, lower leaves first.
Leaves might also appear darker green or have a bluish tint.
Stunted growth and fewer new canes.
Reduced flowering and fruit set.

Other Possible Nutrient Shortages

While phosphorus is the most common cause, other deficiencies can also lead to discoloration. It’s good to check for these too.

Magnesium Deficiency

This often shows as purple or red edges, but with a distinctive yellowing between the leaf veins. It typically appears on older leaves first as magnesium moves to support new growth.

Potassium Deficiency

A lack of potassium can cause leaf scorching, where the edges turn purple or brown and look burnt. The leaf might also curl upward.

Don’t Blame Nutrients First: Rule These Out

Before you start adding fertilizers, consider these other factors. They can look similar or make a deficiency worse.

Cold Spring Temperatures: Cool weather, especially early in the season, can temporarily slow phosphorus uptake, causing purple leaves that often green up as it warms.
Soil pH is Too High: This is a huge one for blueberries. They need acidic soil (pH 4.5-5.5). If the pH is above this range, the plant cannot absorb phosphorus and other nutrients, even if they’re present in the soil.
Poor Drainage or Damaged Roots: Soggy soil or injured roots prevent the plant from taking up nutrients effectively.

Your Step-by-Step Diagnosis and Action Plan

Follow these steps to correctly identify and solve the issue of purple leaves.

Step 1: Test Your Soil pH

This is the most critical first step. You can use a home test kit or send a sample to your local extension service. If your soil pH is above 5.5, you need to lower it. To lower pH for blueberries:

Apply elemental sulfur or a fertilizer for acid-loving plants.
Follow package rates carefully based on your soil type and current pH.
Incorporate it gently into the top layer of soil and water well.
Retest the pH after a few months, as change is slow.

Step 2: Conduct a Visual Check of Growing Conditions

Look at your plant’s environment. Is the soil constantly wet? Are the roots crowded? Ensure your blueberry is in full sun and the soil drains well. Mulch with pine needles or wood chips to maintain moisture and acidity.

Step 3: Apply the Right Fertilizer

Once you’ve adressed pH, you can supplement nutrients. Use a fertilizer formulated for acid-loving plants like azaleas or rhododendrons. These have the right balance.

Apply fertilizer in early spring as growth begins.
Avoid high-nitrogen fertilizers, which can harm blueberries and worsen phosphorus uptake.
Organic options like bone meal are a great slow-release source of phosphorus.

Step 4: Monitor and Maintain

Recovery won’t happen overnight. Existing purple leaves may not fully revert to green, but watch for new growth. Healthy new leaves are your sign of success. Continue with annual soil tests and proper mulching.

Prevention is Easier Than Cure

The best way to deal with purple leaves is to stop it from happening in the first place. Here’s your prevention checklist:

Plant in Acidic Soil: Amend the planting hole with peat moss or composted pine bark.
Mulch Annually: Use 2-4 inches of acidic organic mulch like pine bark or oak leaves.
Fertilize Consistently: Feed with an acid-loving plant fertilizer each spring.
Water Deeply and Regularly: Especially during fruit development and dry spells. Blueberries have shallow roots.

Frequently Asked Questions (FAQ)

Why are my blueberry leaves turning red or purple in summer?

Summer purpleing is almost always a sign of stress, commonly from nutrient deficiency (often phosphorus) due to high soil pH. It’s different from the normal red fall color.

Can overwatering cause blueberry leaves to turn purple?

Yes, indirectly. Overwatering leads to poor root health and can lock out nutrients, leading to deficiency symptoms like purple leaves. Ensure your planting site has good drainage.

What is the fastest way to add phosphorus to blueberries?

A water-soluble fertilizer for acid-loving plants can provide a quicker boost, but correcting the soil pH is the most effective long-term solution. Bone meal is a good organic fast-acting option when worked into the soil.

Should I remove purple leaves from my blueberry bush?

No, there’s no need to remove them unless they are completely dead. They can still contribute some energy to the plant. Focus on fixing the underlying cause so new growth comes in healthy.

Will Epsom salt fix purple blueberry leaves?

Only if the issue is magnesium deficiency. Epsom salt provides magnesium. If the problem is phosphorus or high pH, Epsom salt won’t help and could potentially throw other nutrients out of balance. Always test first.

Seeing your blueberry leaves turning purple can be worrying, but it’s a solvable problem. By methodically checking your soil pH, ensuring proper growing conditions, and providing the right nutrients, you can restore your plant’s health. Remember, blueberries are unique in their need for very acidic soil. Getting that right solves most issues, leading to a season of lush green growth and plenty of sweet berries for you to enjoy.