Should you soak Sweet Pea seeds?

There are two main questions that often get asked about when sowing Sweet Peas - should you soak Sweet Pea seeds before sowing them? And should you chip the outer coating of Sweet Pea seeds?

Soaking Sweet Pea seeds

By soaking Sweet Pea seeds it is supposed to soften the tough outer coating so that the seed can germinate more easily. There are conflicting opinions on whether this is actually beneficial, some experts say it will improve germination and others say it can reduce germination. There are also different methods of soaking Sweet Pea seeds, some recommend soaking in a bowl of water and others recommend on water-soaked kitchen paper.

In nature, it is not guaranteed that all seeds will germinate. If you’re buying good quality Sweet Pea seed that has been harvested and stored correctly you should expect to see a germination rate of around 85%. Other than seed quality, germination rates can also be affected by water, oxygen and temperature. The good news is that with Sweet Pea seeds, it’s relatively easy to get all of these right! We’ll be covering this in more detail in future articles.

The advice to soak sweet pea seeds is believed to have originated from guidance given for seed that was produced in California, where the seeds naturally produce a tougher coating to cope with the climate. The same doesn’t usually happen with seed that has been grown and harvested here in the UK where the climate is much milder.

Chipping Sweet Pea seeds

In the same vein, chipping Sweet Pea seeds is also to aid germination. This involves making a small nick in the coating of the seed, usually with a sharp knife, nail file or sandpaper. The nick should always be away from the hilum which is where the root/shoot will emerge from. The outer coating of Sweet pea seed is a dark brown colour and you will see the hilum is a small light-coloured line.  

So what should you do?

I have germinated lots of Sweet Pea seeds without having to soak or chip the seeds at all so I would say no, it’s not necessary in most instances. There is always a caveat! Sometimes, breeders will notice that the seed coating on a particular harvest is thicker than usual, in this instance they will recommend either soaking or chipping the seed to make sure that gardeners achieve the highest germination rate possible. So, in summary, unless you are advised specifically to do so, you don’t need to!

Of the methods recommended I would soak Sweet Pea seeds on water-soaked kitchen paper rather than in a bowl of water. That way the seed can absorb only the water it needs rather than being waterlogged.

We've carried out a little experiment with some seed that I had seen a lower germination rate and thought it would be useful to share the results so that you can see what happens!

Day 1

The first photo shows the seeds on the water-soaked kitchen paper at the start. The top four seeds have been placed on the paper just as they are and the bottom four seeds have been chipped using a sharp knife and placed with the chip facing down on the paper.

Day 2

So, you can see as early as Day 2 the size of the seed has grown for six out of the eight seeds indicating that they have absorbed some water from the kitchen paper.

Day 3

You can see that the root has started to emerge from the hilum on some of the chipped seeds but not on the un-chipped seeds.

Day 4

You can now see that the root has started to emerge from the un-chipped seed, but we still have two seeds that have not germinated.

Day 5

Based on the results here you can see that three out of four seeds have germinated for both the chipped and un-chipped seed, it’s just taken a little bit longer for the root to emerge on the un-chipped seed.

What you can also see for this particular batch of seed is that we’re getting germination below the 85% we would expect to see. When this happens we add a few more seeds than stated into each packet to make sure that customers get the right number of seeds germinating.

I think it’s really useful to see what is happening below the soil and hope you have found the article useful. If you’ve still got any questions on sowing Sweet Pea seeds you can contact us on the website or follow us on socials and drop us a message.

Happy sowing!

DAY 1

 

 DAY 5