If you’ve followed me for a while, you’ve probably noticed that when seedling season arrives, my germination area is a bit of a mixed bag. There are seedling trays, soil blocks, toilet rolls and little newspaper pots all sitting next to each other.
And after sharing my latest seedling update, someone asked a really good question: When do you use which one?
The simple answer is that I don’t believe there is one perfect way to start every seed. Different plants grow differently. Some don’t mind having their roots disturbed, some develop long roots surprisingly quickly, and others are only going to spend a short time in their container before being planted out.
So I choose my method according to what I’m growing.
But first… my seed-starting mix
Whichever method I’m using, I want my seed-starting mix to be light, fine and able to hold moisture without becoming heavy and waterlogged.
My mix is:
- 40% vermicompost or finely sifted compost
- 30% vermiculite
- 30% coco peat
The vermicompost or compost adds organic matter and some nutrition. The coco peat helps hold moisture while keeping the mixture light. And the vermiculite holds both moisture and nutrients while also helping to keep the mix loose.
One important little tip: if you’re using ordinary compost rather than vermicompost, make sure it is well matured and very finely sifted. You don’t want big pieces of bark, sticks or half-composted material around tiny emerging roots.
Now, let’s get planting.
Soil blocks – one of my favourites
I love soil blocking because there is no little plastic pot around the roots. You press your damp seedling mixture into the soil blocker and it creates individual blocks of growing medium. The seed goes straight into the little indentation at the top. As the roots reach the outside of the block, exposure to air discourages them from continuing to circle around the container. Instead, the root tips stop at the edge and branch within the block – often referred to as air pruning.
When it’s time to transplant, the whole block simply goes into the garden.
I particularly like soil blocks for crops such as:
- Lettuce
- Brassicas like broccoli, cabbage, cauliflower and kale
- Beetroot
- Onions
- Many herbs and flowers
They are especially handy when I’m germinating lots of seedlings at once because I can fit a surprising number into a relatively small area. The downside? They need to be kept at the right moisture level. Allow them to dry out too much and the blocks can become fragile. Water too aggressively from above and you can wash them apart.
I prefer bottom watering wherever possible.
Seedling trays – simple, reliable and practical
There’s absolutely nothing wrong with a good old-fashioned seedling tray. In fact, they’re probably the easiest place to start if you’re new to growing from seed. Seedling trays give every plant its own little growing space, they’re easy to move around and they’re generally very easy to water.
I use them for many of my everyday vegetables, including:
- Tomatoes
- Peppers and chillies
- Eggplants
- Brassicas
- Lettuce
- Herbs
- Flowers
They’re also useful for plants that are going to spend a little longer under protection before I plant them into the garden. The important thing is not leaving seedlings in those small cells for too long.
Once roots have filled the cell, seedlings either need to be planted out or moved into something larger. Leave them too long and those roots can start circling around inside the cell and become root-bound.
Toilet rolls – perfect when roots need a little more depth
Yes, those empty toilet rolls have a place in my garden too! The biggest advantage is their depth. They’re useful for seedlings that appreciate a deeper container or that I don’t want to disturb too much when transplanting.
I like them particularly for things such as:
- Peas
- Beans
- Sweetcorn
- Sunflowers
- Other larger, fast-growing seeds
Fill the tube with your seedling mix, plant your seed and stand the rolls tightly together in a tray so they don’t fall over. When planting time arrives, I don’t simply bury a thick, intact cardboard tube and hope for the best. Cardboard can take time to break down, particularly in drier soil.
I prefer to tear open or remove the cardboard carefully at planting time if it hasn’t already started breaking down. That way the roots can immediately move freely into the surrounding soil. And you’ve turned something destined for the bin into a useful little seedling pot.
Newspaper pots – cheap, easy and surprisingly useful
Newspaper pots are another favourite when I need more individual pots but don’t want to buy more plastic ones. You simply wrap newspaper around a small bottle, jar or pot, fold the bottom underneath and slide it off. Instant seedling pot.
I use these when seedlings need more room than a small seedling tray provides, or when I’ve germinated something and want to pot it on before it goes into the garden.
They’re handy for:
- Tomatoes
- Peppers
- Eggplants
- Larger flowers
- Seedlings that need a little extra growing time before planting out
They are biodegradable, inexpensive and you can make the pot whatever size you need. Just remember that newspaper pots dry out faster than plastic pots and become softer as they’re repeatedly watered. And again, if the paper hasn’t started breaking down by planting time, I gently open the bottom or tear away some of the paper before planting.
So which one is BEST?
That’s the lovely thing. You don’t have to choose just one. For lots of smaller seedlings, I love my soil blocks. For easy, reliable everyday seed starting, I use seedling trays. When I want extra depth, I’ll often reach for a toilet roll. And when I need a larger biodegradable pot without buying anything, newspaper pots are brilliant.
My germination area might therefore look slightly chaotic during seedling season – but there is actually a reason behind it! The container isn’t the most important part. What matters is giving that particular plant the right amount of space, moisture and time to develop a strong root system before it makes the move into the garden. So use what you have, experiment with the different methods and find what works for you.
Because growing from seed doesn’t need to be complicated – and sometimes the best seedling pot is something you were about to throw away.
Happy “almost” Spring
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