Sweet Peas Not Growing Well? Here’s How To Fix It

Sweet peas are usually beautiful, highly fragranced climbing plants that produce stunning flowers, attract pollinators and make lovely cut displays, but sometimes they can disappoint. 

If you encounter problems with the sweet peas in your garden, all is not lost. With a bit of perseverance and the advice here, you can help your sweet pea plants recover from the most common ailments.

If your sweet peas have stunted growth, yellowing leaves, or aren’t blooming, the first thing to check is that they are getting at least six hours of sun per day. Beyond that, the most common reasons for sweet peas growing poorly is too much water or an imbalance of soil nutrition. 

For more specific advice on troubleshooting problems with sweet peas, the advice below will help.

My sweet peas aren’t growing 

Sweet peas are heavy feeders that appreciate rich soil and regular fertilizer. They also need full sun to grow their best. If your plants got off to a strong start but then stopped growing, it could be because there is too little nutrition in the soil, or they’re not getting enough sunlight throughout the day. 

Too little phosphorus

Sweet peas can also benefit from a biweekly feed using an organic, phosphorus-rich fertilizer. You can add phosphorus to your own compost by adding egg shells and banana peels to your compost heap. If you don’t have a compost pile, bonemeal is a readily available, phosphorus-rich amendment.

Too little light

Commonly, sweet peas won’t flower if they are not getting enough light. Typically, 6 hours or so a day is the minimum amount they need. 

If your sweet peas are not in a sunny enough position, you can try moving them to a sunnier spot, but this can be difficult due to sweet peas’ long root tap. 

If you decide to move your plants, loosen the soil around the roots as deeply as possible. Remove the roots with as much soil around them as possible and immediately replant the sweet peas. Dig a hole in a sunnier spot (adding some phosphorus-rich compost, if you have it) and carefully move your plant to its new, brighter home.

If you have planted your sweet peas in pots, moving them is even easier. Just relocate the pot to where it will get eight or more hours of sun per day. 

If you need some ideas for flowers that will thrive in partial shade, get inspired with this article: Can Cut Flowers Grow In Part Shade? (Yes! Try These 9 Types).

My sweet peas are turning yellow 

It can be a helpful warning sign that your plant is unhappy if its leaves begin to turn yellow; in the early stages, there are things you can do to help them recover well.

Too much water

The most common cause of yellowing leaves on your sweet peas is overwatering. Overwatering is signaled by leaves yellowing from the bottom of the plant upwards. It can be easily corrected by simply giving your plants less water or, if they’re in pots, lifting the pots from the ground with bricks to improve drainage.

Root shock

Another cause of yellowing leaves can be that the water for your sweet peas is too cold. I know it sounds unusual, but an experienced gardener shared this with me once, and I found it made all the difference with my sweet peas.

The easiest way to raise the water temperature is by filling a watering can in the morning or a few hours before your average watering time. Leave it in the sun (or the greenhouse, if you’re lucky enough to have one) to warm up before using it to water your sweet peas later in the day. 

My sweet peas aren’t flowering 

It can be frustrating to see your sweet peas grow several feet tall and then not produce the dazzling display of cottage garden flowers you were hoping for. Still, you can encourage your plant to bloom with a few straightforward steps (and, in some cases, a bit of patience).

Too much nitrogen

Too much nitrogen can prevent your sweet peas from flowering. Instead of growing flower buds, the sweet peas will use the excess nitrogen in the soil to continue producing leaves. 

This imbalance is difficult to correct in one season, but you can try adding some lettuce, spinach, or other nitrogen-hungry plants at the sweet peas’ roots to use up the excess. A side benefit is that the leafy greens will help keep the soil cool for the sweet peas, who don’t appreciate hot soil. 

Adding a fine layer of nitrogen-loving wood chips or sawdust to your sweet pea bed will do the trick – sawdust or wood chips will help soak up the excess nitrogen in your soil as they break down.

Too much heat

As temperatures soar, sweet pea flowering can temporarily stall due to temperature fluctuations.

If it has been mild and a sudden scorching spell arrives, the plant can be shocked into being less productive. Luckily, the plants are adept at adjusting to this all by themselves; although flowering will stop, your blooms should reappear in a few weeks as the temperatures drop.

Not enough deadheading

If your sweet pea plant has started flowering but suddenly stopped producing blooms, you can encourage more flowers by picking the flowers it has already made in a process called deadheading.

One of the most wonderful things about sweet peas is that the more blooms you pick, the more they will grow because they are cut and come again flowers. It’s best to pick your flowers early in the morning, at least every three days. 

My sweet peas are dying 

If your sweet pea plants look so unhappy that they appear to be dying, it’s time to take more drastic action to help them recover.

Don’t worry, though; while some of these steps may seem harsh, they will help your sweet pea plants to bounce back and flourish, bringing a beautiful display to your garden, balcony, or outdoor space.

Cut back growth

The first step is to remove any flowering stems already present on the plant. Cutting back the growth means that the plant can put its energy into recovering rather than trying to produce more flowers.

Snip off the side shoots using a clean, sharp pair of gardening scissors before watering it with tepid water and giving the soil a drink of compost tea or all-purpose liquid fertilizer. 

Continue deadheading

Equally important for a dying sweet pea plant is removing seed pods as they appear. Deadheading them will make the plant push out more flowers to try and create more seeds. 

It is worth remembering here that sweet peas only bloom for one season. If you have had a few weeks of perpetual blooms, which you have harvested regularly and removed seed pods as they have appeared, it may be time to say goodbye to your plant for this year and get busy planning next year’s planting.

Final thoughts

Here’s a quick summary of how to troubleshoot problems with growing sweet peas:

• Ensure they are in a sunny spot in your garden or outdoor space.
• Make sure they are getting enough water.
• Use nitrogen absorbing companion plants to balance the soil.
• Support drooping or trailing plants with a trellis or stakes.

Good luck with your sweet peas; following these steps, you should have happily flowering sweet pea plants in no time.