These instructions show how to collect sweet pea seeds for sowing next year. Once your flowers turn to seed and the seed pods are plump, brown, and dry, it’s time to harvest the pods and prepare the seeds for storage.
Love flowers? You can save your zinnia seeds too.
Saving Sweet Pea Seeds
Of all the flowering plants in our gardens, sweet peas (Lathyrus odoratus) pretty much beg us to save their seeds.
During the growing season, these enthusiastic bloomers require frequent picking to encourage new flowers and prevent the flower heads from turning to seed too early.
But, as summer peaks and it gets too hot for these cool-tolerant plants, the cut-and-come-again cycle starts to wane. And that’s when we can let the flowers fade and brown, allowing seed production to begin.
It’s quite something to witness the transformation of those gorgeous blooms as they make way for the gangly, elongated pods filled with tidy rows of seeds.
While sweet pea pods do resemble vegetable garden pea pods, no part of Lathyrus odoratus is edible.
If you’re new to seed saving and trying to develop an eye for it, mark some plants to photograph throughout the process. It’s an excellent way to get more familiar with the entire growth cycle.
- Traditional Method
- Most Reliable Method
Traditional Seed Saving Method
This traditional method for collecting seeds is not always successful but it’s sure simple.
Gardeners are no fools: if there is an easy way to do something and it works for them, that’s how we do it.
Here’s how generations of gardeners have traditionally saved seeds.
- At the end of the growing season, dry seed pods are snipped off the mother plant and collected in paper bags.
- The paper bag is labelled and stashed in a cool, dark place, often in a basement or shed.
- Come spring, the seeds are winnowed (separated from the remaining plant materials), ready to sow.
When this works, it’s great. But the part we overlook is, it works because the conditions happened to be right.
One person can do the exact same thing and end up with a moldy bag of life-less seeds. This may happen when the saved seed pods were damp or the storage space was too humid or some other important condition was not met.
But, if you don’t mind the risk, certainly give it a try. Otherwise, use the instructions below for better odds.
Most Reliable Method
When to Save Sweet Pea Seeds
- Save seeds when seed pods are brown, dry, and plump with seeds inside.
When the summer weather is hot and dry and not letting up, our beloved flowering sweet peas gradually surrender, no longer able to continue flower production.
Over the coming weeks you’ll notice the flowers disappear and these long, dangling seed pods appear in their place.
While the pods start out green like the leaves and stems of the plant, as the seeds form, the pods will gradually appear yellow-ish and then brown.
When the pods are brown, dry, and appear to have plump seeds inside, it’s harvest time.
What Do Sweet Pea Seed Pods Look Like?
This photo (above) shows sweet pea seed pods just after prime harvest time. The pods are long and the color of paper bags. Some of these pods have seeds in them, while a few have already cracked open. When seed saving, it’s best to harvest the pod just before this stage.
Keeping Track of Seeds
If you hope to keep track of your seeds (variety, color), it will take some dedication right from the start.
It begins by marking your favorite flowers while they are in full bloom with an identifying tag.
That tag will follow the seeds throughout harvesting, drying, and storage.
While sweet peas have hermaphroditic “perfect flowers” which can self-pollinate, it is possible for them to cross-pollinate as well so we can’t assume the flowers from saved seeds will be the same as the parents. This likely isn’t a problem, though, unless you’re running a seed growing business and want to keep things sorted.
Realistically, you may not end up with seeds labelled by variety, but having the bag of saved seeds marked “Sweet Pea” may be good enough.
How to Harvest Seed Pods
- Use clean snippers and cut pod stem from plant leaving 3 to 4 inches attached to pod.
Choose a day when the sun has been shining and your pods seem as dry as can be, free of dampness from any recent rains.
Take a clean pair of snippers and cut the seed pod stems, leaving 3 to 4 inches attached to each pod. The stem simply allows easier handling.
How to Dry Seed Pods
- Hang pods to dry or spread out on screen in dry, warm location.
Before removing the seeds from the pod, we first need more time for the pod to dry out, just in case things are damper than they seem.
These next two steps could take a week or a month depending on your harvest conditions.
You can dry your pods indoors or anywhere that has moderate or low relative humidity (preferably below 55%).
There are two options.
1) Hang Dry
- Suspend pods by their stems on an indoor clothesline, allowing them to air dry.
2) Screen Dry
- Spread out pods on an old window screen or hardware cloth.
Raise your screen up so there is airflow on all sides.
When the pods start splitting open, it’s time to remove the seeds for saving.
How to Prepare Seeds For Storage
- Remove seeds from dry pods and allow seeds additional drying time before storing.
With your pods nice and dry and starting to crack open, it’s time to remove the seeds. Some may have already fallen out of the pods.
Before handling the seeds, prepare your work area and wash your hands. It’s handy to put a light-colored cloth down that will catch the seeds and make them easier to see.
Gently pull open the pods and gather your seeds.
Lay seeds out on a paper towel or drying screen and leave until thoroughly dry. Since we don’t have a way to measure the moisture levels, this part relies on guesswork. Often at this point a week is adequate to finish drying.
With your seeds dry, it’s time to store them.
What Do Sweet Pea Seeds Look Like?
The photo (above) shows dry sweet pea seeds ready for storage or sowing.
How to Store Seeds
Just about all garden seeds like the same storage conditions and sweet pea is no exception.
Use these tips to keep your seeds safe and dormant until spring:
Optimum Seed Storage
The lower the temperature and moisture levels, the longer most seeds stay viable.
Best temperature | 32-41°F (0-5°C)
Most fridges are in this range.
Also, room temperature (70°F/21°C or lower) is fine for short-term storage (1 year).
Store dry seeds and keep dry | Relative humidity below 50% | Keep away from light.
If moisture is an issue, use silica gel pack in containers.
How Long Do Sweet Pea Seeds Last?
With optimum storage conditions, the saved seeds should remain viable for 3 to 5 years.
Can I Sow Sweet Pea Seeds Right After Harvesting Them?
Yes, if your growing zone allows it. In hardiness zones 7 and up, which includes the southern United States, it is possible to fall sow sweet pea seeds. The fall and winter weather will naturally prepare them for spring germination.
In colder climates, the seeds need to be protected in storage until conditions are favorable for sowing in spring.
I hope you’ll start adding sweet pea seeds to your homemade seed collection.
If you simply want to purchase seeds, Botanical Interests (US shipping) has lots of beautiful options.
~Melissa the Empress of Dirt ♛