Do you need to soak seeds before planting? We reveal the benefits and 12 seeds you must soak, plus those you shouldn’t

You often see references in sowing guides to soaking seeds before planting them. So, how essential is it to soak seeds before planting? And should you soak all types of seeds?

This guide aims to answer these two questions, and more, as we look at why you should soak seeds and reveal those plants which benefit most from being soaked before planting. If you are a newbie to sowing seeds it can be confusing, so we want to help you get it right.

When it comes to whether to soak seeds before planting, it can be beneficial whether you sow seeds indoors or directly outside in the garden - but is not ideal for all. I deep dive into why and how to soak seeds and look at which seeds you should and shouldn’t soak.

To soak seeds before planting, or not

When working in gardens in the UK, I planned and led large propagation regimes, growing thousands of flowers, vegetables, and herbs from seed each year. Some seeds required extra requirements before planting and factoring that in helped with germination rates and speed. I did take the time to soak seeds before planting, admittedly I did not do it with vast numbers but some were always soaked for quicker germination.

Why soak seeds before planting?

Soaking seeds is beneficial and actively helps germinate seeds, this is because it replicates natural conditions that bring seeds out of dormancy. The soaking softens the hard exterior lots of seeds have to protect the delicate interior, which improves the success rate and speeds up germination.

That hard shell protects against harsh weather and prevents seeds from germinating until the conditions are right. Soaking seeds replicates those ideal conditions and provides the light, warmth, and moisture required to kick-start germination. It triggers the germination process and hydrates the seeds to get them off to a great start.

When you prepare for seed sowing, it is important to consider any special treatments required by seeds to ensure the best levels of germination. Not all seeds need soaking, though some may require other treatments such as cold stratification or chipping to get the best results - and not giving them any required treatment would be a seed-sowing mistake that will impact germination.

If you are thinking of starting vegetable seeds indoors in spring or starting flower seeds indoors or outdoors, be sure to factor in any special requirements.

Is it absolutely vital to soak seeds before planting, no. However, consider the benefits outlined above when planning your seed sowing schedule as the rewards of faster germination can outweigh any hassle involved.

Seeds you should soak before planting

Larger seeds benefit most from being soaked before planting, particularly those with thicker or wrinkled exteriors. Therefore, it is recommended to soak the seeds of the following flowers and vegetables before planting.

They will still germinate fine without being soaked beforehand, and I have had success growing all of the below plants without pre-soaking the seeds, but germination can be sped up thanks to soaking for up to 24 hours before sowing.

1. Peas
2. Beets
3. Cucumbers
4. Beans
5. Pumpkin
6. Squash
7. Corn
8. Chard
9. Peppers
10. Nasturtium
11. Sweet peas
12. Cannas

There are more examples of seeds that will benefit from being soaked. For example, any other medium-sized vegetable or flower seeds will benefit from soaking, though it is not vital to get good germination rates.

But not all seeds are suitable for soaking and small seeds don’t benefit to the same extent as larger ones - plus soaking them can be fiddly. They tend to clump together and are difficult to separate once wet, which can be problematic when attempting to sow them.

How to soak seeds before planting

It is quick and easy to soak seeds before planting, and it can be done if you intend to sow flowers or vegetables indoors or sow seeds outdoors directly into the garden.

1. Fill a bowl or jar with warm water - but ensure it is not too hot, so check with a finger
2. Take your chosen seeds and place them into the water
3. Soak the seeds for 6-24 hours, depending on the size. The largest seeds with thicker exteriors will need the longest amount of time
4. Carefully drain the seeds at the end of their soaking time
5. Plant the seeds quickly into trays or pots filled with seed compost - do not let them dry out after soaking as this can prevent them from germinating

Avoid soaking seeds for longer than 24 hours, as this can cause the seed to suffocate or start to rot and they will not germinate once planted.

FAQs

Should tomato seeds be soaked before planting?

I have never found it necessary to soak seeds before planting when growing tomatoes. Indeed, when looking around online I found a lot of mixed opinions about whether there were any benefits to soaking seeds before planting tomatoes.

Tomato seeds are relatively small and don’t have a large exterior shell, it doesn’t seem practical to soak them before planting and they are likely to stick together after being soaked in water.

Some growers pre-sprout tomato seeds on a damp paper towel, however, I have always found that simply sowing seeds into pots filled with seed compost and giving them temperatures of 65-75°F in a greenhouse or propagator, or on a warm windowsill, has always given great germination results.

Should carrot seeds be soaked before planting?

There is no need to soak carrot seeds before planting. Carrot seeds are tiny and turn slimy when soaked in water, making it difficult to separate and sow them afterwards. When you grow carrots, simply sow them directly into the soil in spring and keep them moist - they should reliably germinate within a few weeks and will likely need thinning.

Before you plant any older seeds from previous years, it is recommended to test the seed viability. This can prevent you from wasting time and energy on old unviable seeds. Luckily, it is quick and simple to do. Simply sprinkle any seeds you wish to test on a damp paper towel and place it somewhere warm. You should see within 14 days how viable the seeds are and whether you simply need to sow more to get good results, or if it is better to buy fresh seeds to plant.