Why My Sweet Pea Leaves Turning Yellow?

Chlorosis is a condition in plants, including sweet peas, where the leaves turn yellow due to various factors like nutritional deficiency, lack of sunlight, infrequent watering, and pests.

Discolored leaves are warning signs from your plant that you must inspect them closely.

Fortunately, you can revive your sweet pea plant even if it has yellow leaves.

It’s sad, but it’s common in plants. As a gardener, you must diagnose the cause of yellowing and revive the plant.

Why are sweet pea leaves turning yellow?

The cause of yellowing could be due to overwatering, underwatering, might need a big container, low levels of nutrients in the soil or high dosage of fertilizers, insufficient sunlight, change in temperature, or pests and diseases.

Apart from this list, it can be a natural process of shedding old leaves.

Your sweet pea plant might not face severe issues, but it can be fatal if ignored.

In this write-up, I’ll discuss each cause in detail and simple steps to revive them. Before that, let me quickly point out some essential requirements of this flowering plant.

Know Your Plant – Sweet Peas Plant

sweet peas turning yellow

This climbing annual flowering plant adds vintage appeal to your gardening space. Prominent for its fragrance and colorful blossoms, you can quickly grow sweet peas plant indoors in a pot.

To produce bountiful flowers that resemble fringed butterflies, you must provide adequate sunlight, well-drained soil, ideal temperature, and sufficient moisture.

  • You must plant this climber in late winter or early spring.
  • Sweet peas need well-drained yet moist soil with alkaline soil.
  • Sunlight: full sun (6 hours of direct sunlight). It can also grow in partial shade.
  • Watering: 1 inch of water every week. , water the plant only when the growing soil is dry.
  • Ideal temperature: Can grow in USDA zones 3 to 8. This plant can tolerate light frost but can’t survive when temperatures exceed 65F.
  • Fertilizing: During the growing season, fertilize with potassium-rich fertilizers. You can also try a blood meal. (Also read about Bone meal)

Providing the correct essential elements is the key to growing healthy plants.

Why Are My Sweet Pea Leaves Turning Yellow?

Overwatering is one of the common gardening mistakes that amateur gardeners do. Apart from this, lack of required nutrients in the growing soil, insufficient sunlight, and plant diseases can result in yellow leaves in sweet peas.

There needs to be more than just knowing essential elements for plant growth. You must maintain the optimal quantity of these elements.

When you fail to do so, plants send flag signs like the yellowing of leaves.

The cause of yellowing could be excess watering, not watering enough, a small container, or over-fertilizing. It could be anyone, them, or it could be a combination.

Gardeners growing sweet peas in a container must provide even watering and sufficient containers to avoid root bound.

1. Watering – Overwatering is one of the most common garden issues

The hardest part of container gardening is even watering.

If you miss a day, it might dry out too much or get excess water. In both cases, plant leaves may turn yellow.

You can only expect a plant to thrive or even grow with water. But you can still give more moisture.


Yellowing of leaves, stunted growth, a sign of root rot, and green algae over the top layer of the soil can be critical indicators of excess watering.

How to revive?

First thing, make sure the potting soil is well-drained. Often, clay soil locks moisture for longer, and you might keep watering without checking the soil.

If you’re growing sweet peas in a hanging basket or container, ensure it has a drainage hole to remove excess water.

Stop watering and if needed move the plant to a better location that gets sufficient sunlight.

Start watering the plant only when you notice the plant soil is dry.


Interestingly, insufficient moisture will lead to stunted growth, drooping, and yellowing of leaves.

But, the growing soil looks bone dry.

How to revive?

Check your growing soil; can it retain moisture for a longer time?

Start with deep watering and use hay grass or organic material to mulch around the plant.

Mulching will reduce moisture evaporation into the atmosphere.

You must know how often to water your sweet peas plant to avoid watering issues.

As a thumb rule, water your plant only when you notice the soil is dry by 1 inch.

2. Lack of Nutrients

NPK are three essential nutrients every plant needs to bloom, fruit, and develop the root system.

Growing soil lacking such essential nutrients results in nutritional deficiency, reducing flowers and turning foliage yellow.

A deficiency in nitrogen results in the yellowing of leaves, and if only the edges of leaves are turning yellow, then it might denote a deficiency in potassium.

Manganese deficiency also results in yellow sweet peas plant leaves. Manganese plays a vital role in the production of chlorophyll; lack of this nutrient results in chlorosis.

How to revive?

Conduct a soil test to determine pH and nutrients in it.

Accordingly, add balanced nutrients to sweet pea plants to enrich the soil. Water the plant after applying fertilizer so that roots can uptake nutrients.

3. High Usage of Fertilizers

Balancing nutrient levels is very important to grow a successful sweet peas plant. For instance, phosphorus elements encourage the plant to bloom, while nitrogen helps to produce chlorophyll.

However, high dosages of nutrients can result in yellowing of leaves, stunted growth, dropping of leaves, and brown leaf tips.

You can also see a salt layer over the surface of the soil.

How to revive?

If you notice a white layer on growing soil, remove it and water deeply. Only fertilize the plant for a month or once you see the plant is salvaged.

Conduct soil tests before fertilizing.

Also Read: Can You Mix Epsom Salt With Fertilizer?

4. Insufficient Sunlight

Sweet pea plant needs sunlight and water to produce chlorophyll, a pigment responsible for green foliage. Lack of soil sunlight makes the plant leggy and turns leaves yellow.

How to revive?

Sweet pea plants need full sunlight to grow.

Shift the plant container to a better location where it gets adequate sunlight.

You can also choose a location that gets enough sunlight in the morning and partial shade in the afternoon.

5. Compact Roots

Roots are responsible for providing water along with nutrients to plants.

Root-bound makes them inefficient, and they can’t deliver the required nutrients to the plant.

Yellowing of leaves and compact roots are signs of this garden issue.

How to revive?

If you notice the container isn’t enough for plant roots, repot the sweet peas plant to a bigger container.

6. Growing Soil

Sweet pea plants needs well-drained and alkaline soil.

Choosing the wrong soil that doesn’t let excess water out can often result in overwatering, eventually leading to root rot.

How to revive?

Container gardeners must choose potting soil mixed with garden soil, coco peat, compost, and perlite. These ingredients ensure water drainage while preserving moisture for an extended period.

7. Not Providing Ideal Temperature

A sudden temperature change isn’t good for plants.

Sweet peas can’t tolerate higher temperatures.

Thus, plant leaves may turn brown when exposed to temperatures above 65F.

How to revive?

Choose a location that protects the plant from high temperatures. Use a shade cloth to avoid scorching sunlight, or shift the pot indoors.

8. Pests & Diseases

Mosaic virus, Powdery mildew, Spotted wilt, and Ramularia leaf spot are fungal infections that can result in the yellowing of sweet pea plants.

Depending on the infestation, you will find yellowing, mottling, circular, or greyish-white spots on the leaves.

How to revive?

Diagnose the plant disease or infestation and use fungicides available to remove them.

How to Prevent Yellow Leaves on Sweet Peas?

Though not so severe, the causes, as mentioned earlier, can result in unhealthy sweet pea plants.

In most cases, you can salvage your plant, but there can also be rare instances that may prove fatal for the plant.

Instead, if you practice healthy gardening, sweet pea plants will gift you back by beautifying your space.

Remember this: Overwatering is one of the common reasons why sweet pea leaves turn yellow. Avoid it.

You don’t have to worry much if you’re growing sweet peas in a garden.

Container gardeners must ensure they even water the plant. As mentioned, it is hard.

  • To avoid overwatering, choose well-drained soil with balanced nutrients.
  • Also, growing soil must effectively retain moisture. You can add coconut coir to the garden soil. It can hold moisture for a longer time.
  • Sweet peas need full sun to thrive. Else, you might see discolored leaves.
  • Ensure the plant location gets 6 hours of direct sunlight.
  • The container should be big enough to avoid root-bound and a drainage hole that lets excess water out.
  • Avoid temperatures above 65F.
  • Maintain balanced fertilizer. Experts recommend soil testing before applying fertilizers.
  • Fertilize monthly once.
  • Closely watch for pests and diseases. Use fungicides at early stages to combat diseases.
  • You can also cut infected twigs or leaves to avoid further spread.

Note: Water sweet peas plant only when the soil is dry by 1 inch. You can check it by inserting your index finger into the growing medium.


Why sweet peas leaves are turning yellow, you shouldn’t expect a one worded answer to this question.

Initially, you must diagnose the plant and its soil to determine the root cause.

In most cases, experts held overwatering and compact root to yellowing of leaves.

Ensure you’re not overwatering your plant; repot the plant into a bigger pot if needed.

You can inspect the plant leaves to confirm the cause if it’s due to pests and diseases.