Why My Sweet Pea Leaves Turning Yellow?

Even with yellow leaves, your sweet pea plant can be salvaged.

Discoloured leaves are warning signs from your plant that you must inspect it closely.

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

Why sweet pea leaves turning yellow?

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

Your sweet pea plant might not be facing serious issue, but can be fatal if ignored.

In this write-up I’ll be discussing about each cause in details and simple steps to revive them. Before that let me quickly point out some key requirements of this flowering plant.

Know Your Plant – Sweet Peas Plant

watering sweet peas

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

To produce bountiful of flowers that resembles 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). Can also grow in partial shade.
  • Watering: 1 inch of water every week. In simple words, 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 the temperature is above 65F.
  • Fertilizing: During growing season, fertilize with potassium rich fertilizers. You can also try blood meal. (Also read about Bone meal)

Providing right amount of essential elements is the key to grow healthy plants.

Why Are My Sweet Pea Leaves Turning Yellow?

New gardeners particularly, container gardeners overwater the plants. This is one of the common gardening issues.

Knowing essential elements for plant growth isn’t enough. You must maintain optimal quantity of these elements.

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

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

Gardeners who’re growing sweet peas in a container got to provide even watering and sufficient container to avoid root bound.

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

Hardest part in a container gardening is even watering.

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

You can’t expect a plant to thrive or even grow without water. But, this doesn’t mean that you give too much moisture.


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

How to revive?

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

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

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, not providing enough 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 longer time?

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

Mulching will reduce moisture evaporation into the atmosphere.

To avoid watering issues, you must know how often to water your sweet peas plant.

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 root system.

When growing soil lacks such essential nutrients, it results in nutritional deficiency reducing flowers and turning foliage to yellow.

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

Manganese deficiency also results in yellow sweet peas plant leaves. Manganese plays vital role in production of chlorophyll, lack of this nutrients result in chlorosis.

How to revive?

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

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

3. High Usage of Fertilizers

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

But, high dosage of nutrients can results in yellowing of leaves, stunted growth, dropping of leaves and brown leaf tips.

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

How to revive?

If you notice white layer on growing soil, remove it and water deeply. Don’t fertilize the plant for a month or until you see the plant is salvaged.

Next time before fertilizing, conduct soil test.

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 sunlight makes the plant leggy and turn leaves yellow.

How to revive?

Sweet peas plant 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 afternoon.

5. Compact Roots

Roots are responsible to provide water along with nutrients to plant.

Root bound makes them inefficient and they can’t deliver 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 bigger container.

6. Growing Soil

Sweet peas plant needs well-drained and alkaline soil.

Choosing wrong soil that don’t let excess water out can often result in overwatering, which eventually lead to root rot.

How to revive?

Container gardeners must choose potting soil mixed with garden soil, coco peat, compost and perlite. These ingredients ensure the water is drained and it also locks moisture for longer period.

7. Not Providing Ideal Temperature

Sudden change in temperature isn’t good for plants.

Sweet peas can’t tolerate higher temperatures.

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

How to revive?

Choose a location that protects plant from high temperatures. You can 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 yellowing of sweet pea plant.

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

How to revive?

Diagnose the plant disease or infestation and use fungicide available in the market to get rid of them.

How to Prevent Yellow Leaves on Sweet Peas?

Though not so serious, above mentioned causes can results in unhealthy sweet pea plant.

In most cases you plant can be salvaged but there can also be rare cases that can turn the plant fatal.

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

Remember this: Overwatering is one of the common reasons why sweet peas leaves are turning yellow. Avoid it.

If you’re growing sweet peas in garden, then you don’t have to worry much.

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 longer time.
  • Sweet peas need full sun to thrive. Else, you might see discoloured leaves.
  • Ensure the plant location gets 6 hours of direct sunlight.
  • Container should be big enough to avoid root bound and a drainage hole that lets excess water out.
  • Avoid temperature 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.


You can’t one worded answer to the question, why sweet peas leaves are turning yellow.

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

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

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

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