Best Fertilizer for Sweet Peas + How to use them

Nutritional needs of sweet pea plant changes along with its growth.

In initial stages, every plant including sweet peas need balanced NPK ratio to promote root growth, stem development and leaf formation.

But, adult sweet peas need high amount of phosphorus and potassium to promote flowers.

You can either homemade fertilizer or synthetic fertilizers available in the market to fertilize sweet peas. (Source)

If you’re adding decomposed compost or worm castings while planting sweet peas, then you don’t have to worry much about fertilizing this annual flowering plant. (Source)

However, you can add potash rich nutrients to increase flowering of sweet peas.

Remember this: Over fertilizing may result in bushy plant with no flowering. Similarly, under fertilization will affect plant growth.

Importance of Fertilizers for Sweet Peas

fertilizer for sweet peas
  • Regular watering will leach nutrients from the growing medium. When the soil lack nutrients, your plant will suffer to produce attractive blossoms.
  • Sweet pea plant gets food from sunlight, but it is not the only food source. Like other flowering plants, sweet peas need other nutrients as well to thrive.
  • In most cases, potting soil mix has those nutrients. But, during growing season, your sweet peas may need heavy nutrient boost.
  • This why you’re advised to use fertilizer twice in growing season.

Why do sweet peas need fertilizers in the first place?

In the wild, sweet peas or Lathyrus odoratus has plenty of organic matter like dry leaves, helpful bacteria and other nutrients in the soil that is been added naturally.

But, your backyard garden or container may fail to provide similar nutrients. To recreate this, you have to use organic or synthetic liquid fertilizers available in the market.

Remember this: Not all fertilizers can be able to provide macro-nutrients that your sweet peas need. You must use a mix of organic and synthetic fertilizer to encourage plant growth.

What Nutrients Do Sweet Pea Need?

As mentioned earlier, young sweet pea plant need balanced NPK 10-10-10 so that it can actively grow it’s roots, make stems stronger enough and promote foliage.

If you added old compost while planting sweet peas, then you don’t need to fertilize sweet peas in initial stages.

However, when the plant is about to bloom, adding potash rich fertilizers will encourage the plant to bloom extensively.

There are bunch of water soluble fertilizers for flowering plants like sweet peas. Along with it liquid fertilizers, you can also use organic fertilizers which releases nutrients into the soil slowly with regular watering.

Also Read: How to Grow Everlasting Sweet Peas?

Best Fertilizer for Sweet Peas

There are few gardeners who would like to use only organic fertilizers like compost tea, decomposed manure and worm castings. These are good for sweet peas, as they are high in carbon that helps sweet peas to bloom.

But, sometimes these alone may not provide required amount of macro-nutrients your sweet peas need during growing season.

This is why gardening experts recommend using liquid fertilizers made specifically for flowering plants.

Liquid fertilizers has quick and readily available nutrients for the sweet pea plant.

  • Sweet pea seedlings need balanced amount of macro-nutrients that encourage overall plant growth.
  • As the plant reaches growing season, you should reduce nitrogen ratio and use potash rich fertilizers to promote blossom production.
  • Phosphorus and potassium rich fertilizers contribute in flowering and strengthening of plant roots.
  • While planting sweet peas, add fertile rich soil along with worm castings. This organic fertilizer has NPK rating of 5.5.3.

Best Homemade Fertilizer for Sweet peas

Comparatively, organic fertilizers may take longer time than synthetic fertilizers to enrich the growing soil. But, they are safe and will provide your sweet peas with balanced amount of macro and micro-nutrients.

Before adding phosphorus and potassium rich fertilizers, you should conduct soil test to determine nutrients in it. Or if see the plant is growing busy with no flowering, then most likely you provided your sweet peas with lots of nitrogen.

#1 Bone Meal

Bone meal is rich in phosphorus, adding it sweet peas can increase flowering.

Nutritional value of this organic fertilizer is 3-15-0.

Bone meal is made from dried finely powdered animal bones, it is high in calcium and phosphorus, adding them as fertilizer will enrich soil and help your sweet peas bloom.

#2 Kelp Meal

Kelp meal is seaweed fertilizer that is rich in potassium. Add liquid kelp per gallon of water to fertilize your sweet peas. (Source)

Kelp Meal is an organic fertilizer made from seaweed, which is rich in naturally occurring potassium. NPK ratio of this fertilizer is negligible, but you can add it fish emulsion to increase trace minerals.

#3 Greensand Fertilizer

This is inorganic soil amendment that is rich in potassium. Unlike organic matter, greensand may take little longer time to release macro-nutrients.

If your soil is deficient in potassium, then adding greensand while planting will help to improve vigor of sweet pea plants.

#4 Granite Meal Fertilizer

It is a organic soil amendment that enrich your growing soil by slowly releasing potassium, calcium, aluminium and other trace elements. (Source)

Conduct a soil test before adding granite meal fertilizer to sweet peas.

#5 Rock Phosphate

As the name suggests, this organic fertilizer is rich in phosphorus and is extensively used by gardeners to strengthen their flowering and vegetable plants.

Rock phosphate is extracted from clay deposits that are rich in phosphorus. It is available in liquid and dry form.

Apply rock phosphate before growing season, it will encourage sweet pea plants to produce more flowers.

#6 Compost Tea for Flowering Plants

If you want to reduce reliance on chemical fertilizers, then you should compost tea brewed in your backyard.

Being a liquid extract of old compost, compost tea has essential macro and micro nutrients that can benefit your flowering plant.

As nutrients are readily available, they are easily absorbed by plant roots.

You can make your own compost tea at home, read on this guide.

How to Fertilize Sweet Peas?

As already mentioned, sweet peas need balanced fertilizers at initial growing stage. You must add potash rich feeds as the is about to bloom.

  • You can either use liquid fertilizer before growing season or add layer of dry fertilizer at the base of sweet pea plant.
  • Gardeners, who are growing sweet peas in pots must add old compost to potting mix.

How Often to Fertilize Sweet Peas?

2 times during growing season to promote flowering.

Those gardeners who are growing sweet peas in hanging baskets or containers must fertilize sweet peas after every few weeks.

Sweet peas in container needs more nutrients when compared to those grown in ground.

If you already added compost manure during planting, then don’t fertilize the plant till it reaches certain height.

Over-fertilization with nitrogen results in bushy plant leaves with no flowering.

Over-fertilizing Sweet Peas

When you give your sweet peas fertilizer, be careful not to use too much. Too much nitrogen can cause lots of leaves to grow but not many flowers.

To prevent that problem, use fertilizer that has a balanced amount of nitrogen. Or you can also use a liquid fertilizer with less nitrogen in it.

During initial stages, you can use balanced compost manure to provide the required amount of macro and micro-nutrients.

When fertilizing sweet peas use liquid fertilizer with low nitrogen content to promote flowering.

Organic Vs Synthetic Fertilizer

Organic fertilizers are safe and is packed with with balanced macro and micro-nutrients that are essential for sweet peas.

However, it may take time to break down to form essential compounds, that helps sweet pea plants to grow.

On other hand, synthetic fertilizers are quick and readily available with good NPK ratio.

It is important to use right kind of fertilizer in right amount to enjoy blooms and long lasting sweet pea flowers.

What are the Different Types of Garden Fertilizer?

  1. Granular
  2. Liquid
  3. Spikes

Granular and liquid fertilizers are very prominent.

Granular fertilizers are dry fertilizers that releases nutrients to the soil slowly. However, there are few granular fertilizers that are capable of releasing nutrients into the soil quickly.

Liquid fertilizers on other hand is easy to apply and it gets absorbed by plant quickly. You can opt for liquid fertilizer to enrich sweet peas.

Spikes are sticks that are inserted into the soil. It releases nutrients into the soil gradually.

How Do I Know if My Sweet Pea Need Fertilizer?

If you notice leaves of your sweet peas are pale or yellowish, then it might be a sign of nutrient deficiency.

You can use blend of liquid fertilizer and granular organic fertilizers.

Also Read: Why My Sweet Pea Leaves Turning Yellow?

When Should I Fertilize Sweet Pea?

It is best to fertilize sweet peas once after the initial growth and right before blooming period.

You can also give second dose of fertilizer during flowering season, if plants are showing sign of nutrient deficiency.

To make sure your sweet pea stays healthy, use liquid or granular fertilizer with low nitrogen content as high nitrogen may prevent flowering.

Sweet Peas Plant Care Tips

For optimal growth, you must provide adequate sun exposure, sufficient water and enrich growing medium with fertilizers at regular intervals.

  1. Plant sweet peas in a sunny location, where it gets full sun.
  2. Add organic matter like compost or manure into the potting soil while planting.
  3. Over-watering is one of the common gardening problem, if you’re growing sweet peas in pots ensure it has a drainage hole.
  4. Most sweet pea varieties are climbers, they need at least 6 feet of good support.
  5. Ensure the plant isn’t overwatered or underwatered.
  6. Fertilize regularly, using a balanced fertilizer such as 10–10–10 or 5–5–5 formula, to encourage plant growth. For boost flowers, you should use phosphorus rich fertilizers.
  7. To make sure your flowers remain vibrant and continue to bloom, it is essential to deadhead them regularly by plucking off faded petals.
  8. Pinch back newly planted shoots to allow bushier growth in later stages of life cycle.
  9. After growing season, trim old woody stems else the plant will drain energy from fresh stems resulting in reduced flowering in next growing season.
  10. Mulch with hay grass around the sweet pea plant to improve water holding capacity of the soil and avoid weed growth.


Sweet Peas are one of the prominent ornamental plants, you can grow them in containers or in the ground.

Fertilizing sweet peas need to be changed according to plant’s growth.

Sweet peas seedlings need balanced NPK ratio to strengthen it’s stems and roots. But, well grown sweet pea plants need to be fertilized with phosphorus and potash rich feeders.

It is recommend to soil test before adding nutrients.

During growing season, enrich the soil with organic fertilizers twice.

Container sweet peas need to be fertilized after every few weeks.