Best fertilizer for sweet peas | + When to apply

The best fertilizers for sweet peas are pelletized chicken manure, worm castings and compost. These are high carbon and lower in nitrogen which will help to grow more flowers. Liquid seaweed can be added as the sweet peas grow to strengthen roots and stems.

How often to fertilize sweet peas

Fertilize sweet peas before planting by digging compost, worm castings and pelleted chicken manure into the soil. Adding fertilizer before planting will build organic matter and nutrients into the soil.

Do not fertilize the sweet peas at all after planting. Too much nitrogen fertilizer will encourage a big leafy plant but few or no flowers. If this happens you could add a phosphorus-based fertilizer like Richgro Organic Phosphorus fertilizer. This will encourage flowering.

When to plant sweet peas

If you live in a cooler area, these can be sown in spring. If you have mild summers they will grow over the summer months.  If you live in warmer areas, like me in Sydney Australia or the Southern States of the USA, then wait until Fall or Autumn when the weather starts to cool off.

• Southern States of the US – Plant in Fall (September-November USA) for winter and early spring flowering.
• Northern States of the US or cooler areas – Sow in Spring (March – June USA)

Why sweet peas are not blooming

There are a few reasons why your sweet peas may not be blooming and producing those amazing pink, red and white flowers we all love. Let’s go through them.

Fertilizer

The best fertilizer for sweet peas is organic compost or a small handful of pelletized chicken manure dug into the soil before you plant out the seeds. If you have really good, rich, dark soil then you may not need to add any fertilizer before planting at all. You can just scrape back the mulch in your flower beds, sprinkle in the seeds and cover them with the soil. Give them a good water and they are an easy annual flower to grow.

Sunlight

If your sweet peas are not getting enough sun they won’t bloom to their fullest. They like about 6-8 hours of sunlight per day, this doesn’t have to be direct but they like bright light and longer days. If you can, choose the brightest, sunniest spot in your garden to encourage your sweet peas to bloom to their fullest.

Dead heading the flowers

To keep your sweet peas flowering for longer, trim the dead flower heads off with garden secateurs. Just snip the dead flowers off and this will encourage the plant to continue to flower. If you leave the flowers on, the plant will focus on producing seeds instead.

Towards the end of the growing season, I will leave the flowers on the plant, letting the plant form seeds so I can save them for the next year.

What to do with sweet peas when they finish flowering

At the end of the growing season the best thing you can do is to save the seeds from your sweet peas and dig the rest of the plant into your garden bed or add it to your compost. Here is a step-by-step guide to saving sweet pea seeds to grow the next year.

Step 1: Choose heirloom plants – If you plant heirloom seeds you can save the seed and it will look the same. With modern hybrid plants, the seed you save may not look like the plant you grew. Even though mine aren’t heirloom, I will save the seed anyway and see what happens.

Step 2: Choose the best flower heads and leave them on the plant.

Step 3: Let the flower head die off and dry on the plant, the seeds will form inside the flowers.

Step 4: Let the seed pod dry and turn brown. This can take around 2 weeks, but make sure you pick them before they crack open fully as they will drop the seed on the ground.

Step 5: Pick the whole flower head with the seed pods, put them in a paper bag. Make sure the bag is 100% paper and not plastic lined. This will help the seeds to dry out. You may need to wait a few extra days for the seeds to dry out completely.

Step 6: Shake the bag and the seeds will fall away. You can then remove the rest of the flower stem and the seeds will be ready for you to plant the next year.

Step 7: Store in a cool, dry place in the paper bag or transfer them to a mason jar. I suggest putting a piece of paper towel in the jar so it can absorb any extra water that still might be in the seed.

If you don’t want to save seeds you can just let the seed pods form and drop seeds where you grew them. The seeds will sit in the soil and sprout again in the next fall.

How to stake sweet peas

Sweet peas can grow over 8 feet tall so it is best to stake them if they are planted out in an open area. The best way to stake sweet peas is to use a timber stake, knocked into the ground around 2 feet apart. You can then scatter the seeds around the stakes. As the peas grow, use gardeners string to tie them to the stake.

I am growing mine in my garden beds, between walls and trees so I am hoping that this will provide enough support for the peas. If they start to fall, I will do my best to gently knock in some stakes, trying not to damage any roots in the process.

When to plant sweet peas

If you have been inspired to plant sweet peas, then can you still plant them in Fall in warmer areas or spring in cooler areas.

Growing sweet peas in my own garden

I have recently planted 3 packets of sweet peas in different spots in my garden. They are all growing at different rates, with those that get the most sun popping up first. The sweet peas in (almost) full shade are just poking their heads through the soil 2-3 weeks after planting them.

Once they grow up a bit, they will be able to reach through and get more sunlight. This will be perfect to encourage flowering and they will also have something to lean on, like the wall behind them or the lemon tree in front.