How to Grow Sweet Peas: 5 Tips for Growing Sweet Peas

Learn how to grow sweet peas with these 5 tips, and add beautiful and sweet-smelling blooms to your garden. Sweet peas are a relatively easy flower to grow and can add beauty, fragrance, and charm to any garden.

I first saw sweet peas at The Butchart Gardens in British Columbia, and I was blown away by their beauty. When I grew my own, I was blown away by something else… the smell! I wish you could smell them. People often tell me this flower (and the smell!) reminds them of their mom’s or grandma’s garden.

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5 Tips for How to Grow Sweet Peas

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1. Plant sweet peas early in the season

The best time to plant sweet peas depends on your location and climate, but in general, sweet pea seeds can be directly sown into the ground in early spring or fall, when the soil temperature is around 50-60°F (10-15°C).

Sweet peas prefer cool soil and bloom best before the weather gets hot. In zones 7 and colder, start seeds indoors and transplant sweet peas as soon as the soil is dry enough to work in. Don’t wait until after the last frost.

In mild winter areas (zone 8-10) like the low desert of Arizona, plant in the fall from October through January.

Start seeds indoors:
September – January
Plant seeds or transplants outside:
October – February

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2. Choose the best type of sweet peas for your area and preferences

Many sweet pea varieties are day-length sensitive, meaning they grow best in certain areas of the country. Choose a type that will grow well in your area. The fragrance differs between types as well. 

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3. Plant and care for sweet peas as they grow

Choosing a location:

In most areas, choose a location in full sun. Sweet peas prefer full sun and well-drained soil. Choose a location that receives at least 6 hours of sunlight per day and has good drainage. If your summers are very hot such as in Arizona, choose a location that gets morning sun and some afternoon shade. 

Sweet peas grow well in soil amended with plenty of compost and organic matter. Sweet peas prefer soil a bit on the alkaline side; amend with lime if soil is acidic.  

How to plant sweet peas:

• Plant seeds 1 inch deep, 2-3 inches apart. Thin to about 5 inches apart when seedlings are 2-3 inches tall so that each plant has enough space to grow and receive enough nutrients.
• For square foot gardening, plant 4 sweet peas per square. 

Caring for sweet peas:

• Mulch around the base: Mulching around the base of the sweet pea plant can help retain moisture in the soil and reduce weed growth.
• Provide regular water and fertilization: Sweet peas need regular watering and fertilization to produce healthy plants and abundant blooms. Water deeply and consistently, and fertilize every few weeks with a balanced fertilizer.
• Watch for pests and diseases: Sweet peas can be susceptible to pests and diseases, such as aphids, slugs, and powdery mildew. Look for any signs of infestation or disease and take action as needed.

Pruning sweet peas:

• Pinch off the tips of young plants: When the young plants have developed four to six leaves, pinch off the top one to two inches of growth. This will encourage bushier growth and more blooms.
• Remove dead or damaged growth: As with any plant, it’s important to remove dead or damaged growth. This will help promote healthy new growth and prevent disease.
• Remove spent flowers: As mentioned earlier, removing spent flowers (deadheading) can help prolong blooming and encourage the plant to produce more flowers.
• Cut back after the first flush of blooms: Once the first flush of blooms has faded and if temperatures are still cool, you can cut the plant back by half to encourage new growth and more flowers.
• Don’t prune too hard: While pruning can be beneficial, it’s important not to prune too hard or too late in the season. Pruning too hard or too late can remove next year’s blooms and weaken the plant.

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4. Give sweet peas support as they grow

Most sweet peas can grow to heights of 8-10 feet. Put trellises in place before you plant so as not to disturb the roots. Guide young plants to the trellis and then tendrils will find supports and climb.

Remember to choose a support structure that is sturdy enough to hold the weight of the sweet pea vines as they grow. It’s also a good idea to provide support early on in the sweet pea’s growth to avoid damaging the plant later on.

Ideas for supporting sweet peas:

• Trellis: One of the most common ways to support sweet peas is to use a trellis. You can buy a trellis or make your own from wood or bamboo stakes. Train the sweet pea vines onto the trellis as they grow.
• Netting: Another option is to use plastic netting, which can provide support for the sweet pea vines as they climb. You can attach the netting to wooden stakes or plastic poles.
• Arches: If you want to create a unique look in your garden, consider using arches to support your sweet peas. You can buy metal or wooden arches, or create your own from bent PVC pipes.
• Fences: If you have a fence in your garden, train the sweet pea vines to climb up it. You can also attach netting or string to the fence to help support the vines.
• Obelisks: Obelisks are tall, narrow structures that can provide support for sweet peas. You can buy obelisks or make your own from wood or bamboo stakes.
• Hanging baskets: Sweet peas can also be grown in hanging baskets. Plant the sweet pea seeds in the bottom of the basket and train the vines to climb up the sides and over the top.

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5. Tips for encouraging more sweet pea blooms

To prolong sweet pea blooms, you can take a few steps:

Deadhead regularly: As the sweet peas begin to fade or wilt, remove them to encourage the plant to keep producing more flowers. Harvesting sweet peas regularly can help promote more blooms and prevent the plant from becoming too leggy or top-heavy.

Keep the soil moist: Sweet peas prefer well-draining soil that is consistently moist but not waterlogged. Water regularly, especially during dry spells, and make sure the soil doesn’t dry out completely.

Fertilize regularly: Sweet peas are heavy feeders and can benefit from regular fertilization if you have a long growing season. Use a balanced fertilizer every 3-4 weeks if desired.

Provide support: This will help the sweet peas produce more blooms and help prevent the plant from becoming tangled or overstressed.

Keep them cool: Mulch around the base of the plant to help keep the soil cool and the roots moist.

Harvesting tips for cut flowers

• Once blooms begin, harvest at least every other day to encourage blooming.
• Blossoms will not open more once cut; harvest when all but the top few blossoms are open.
• Harvest blooms in the morning. 
• Put stems in water right away.
• Blooms last 5-7 days; adding sugar or a floral preservative will increase vase life by a few days.

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Overall, sweet peas are a relatively easy flower to grow and can add beauty, fragrance, and charm to any garden. Provide them with the right growing conditions and support, and you’ll be rewarded with a stunning display of flowers.

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Comment below if you have questions about how to grow sweet peas, or share varieties of sweet peas you’ve tried and loved. 

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