QUESTION: Why are my strawberry leaves turning red? Aren’t they supposed to be green? What’s happening? – Arlo J
ANSWER: There are several reasons that strawberry leaves might turn red.
Acidic or Alkaline pH Level
Strawberries prefer soil with a neutral pH level, around 7.0. If the pH level of the soil varies too much from neutral, the foliage can turn red. (Not sure what the pH level of your soil is? See our article How to Test pH in Your Soil.)
If your strawberry leaves have turned red when winter weather rolled in, cold temperatures may be the cause of the discoloration. Plants that have red foliage due to cold weather will also stop growing during the wintertime. Just leave the plants alone, and their foliage will turn green again when the weather warms up in spring.
Fungal diseases like leaf scorch can be to blame when strawberry plant leaves turn red. If you see purple and red leaves on your strawberry plant, then the problem is definitely fungal disease. Stems will be red along with the leaves. Red leaves will turn brown gradually, then die.
If one of your strawberry plants is infected with fungal disease, the only thing you can do is attempt to control its spread. You’ll need to remove and discard any plants that show signs of fungal disease. Don’t use the plants as compost or you risk spreading the disease along with the compost when you use it.
Fungal diseases are helped along by an overly moist environment. While there’s nothing you can do to treat plants that have turned red due to fungal disease, you can take steps to stop it from happening again.
First, make sure that your watering technique is flawless. You’ll want to ensure that all the water is aimed at the base of the plants so that the roots can absorb the moisture as it soaks in. Water that hits the soil far away from plants, or water aimed at the leaves of the plant instead of the base, can’t be absorbed and used by the plants. They can only use water that is accessible by their roots.
You’ll also need to make sure that you aren’t giving plants too much water. There’s a simple test you can do to determine whether it’s time to water your plants. Just stick a finger into the soil near where your strawberry plants are growing. If the ground is moist to the touch or the soil sticks to the skin of your finger, it’s still moist and it isn’t yet time to water your plants again.
Plants need nitrogen, potassium, and phosphorus to thrive. If the soil needs more of any of these nutrients, your plants can show it with discoloration of their foliage. Red leaves on strawberry plants specifically point to a phosphorus deficiency, but you’ll need to test your soil using a soil testing kit to find out for sure.
Before you add more phosphorus to your soil, you need to address the red leaves that are already on your plants. Use a clean, sterilized pair of gardening shears to clip the leaves that are red where they meet the main stem.
Then, adding either bone meal or phosphate to your soil can increase the amount of phosphorus it contains. Bone meal releases more slowly than phosphate.
If you’re using bone meal, loosen the soil around the edges of the bed where your strawberry plants are growing and mix in a bit of bone meal. Add some fertilizer to these sections while you’re at it. Don’t put the bone meal too close to your strawberry plants. Just add it around the edges of your garden bed.
You may decide to use phosphate since it releases more quickly. You can find phosphate in a water soluble powder. Mix one teaspoon of the powder in with one liter of water, then measure into containers that hold 100 to 150 ml. Use one container to treat the soil every two to three weeks.
Follow these directions carefully, and resist the urge to over fertilize your strawberry plants. Too much of these remedies won’t do them any good and can actually harm them.
Too Much Carbon
As carbon in the soil increases, the microorganisms that break soil down into the nutrients plants can use need more nitrogen to get the job done. If they don’t get that increase in nitrogen, the carbon doesn’t get broken down and, as a result, your strawberry plant’s leaves may turn red.
A few materials used in gardening that have high carbon content include pine needles, sawdust, and straw. Use a light hand when you apply these ingredients, and stop using them completely if you suspect there’s too much carbon in your soil.
Now you know the likely suspects behind your strawberry plants’ leaves turning red. Once you have determined the culprit behind the discoloration, you can take the necessary steps to correct the problem.