Seed bombs are balls of (you guessed it) seeds – usually wildflowers – held together with clay and compost. But what are they for? How do they work? And how can you make them?
This 101 guide holds the answers to your burning questions about these potential-packed balls of plant life.
What's the point of seed bombs?
Seed bombs are a staple weapon in the guerrilla gardener's arsenal. These subtle, pocketable pellets let you grow on-the-go. Unlike less sneaky methods of guerrilla planting – like getting down to the ground with a trowel – seed bombs let you instantly plant anytime, anywhere, without leaving your hands and knees dirty.
There's a bouquet of reasons this is a great thing to do: wildflowers feed our key workers – the bees – and other insects, in turn supporting the wider wild ecosystem; they keep soil stabilised and nutrient-rich; all while bringing mood-boosting colour to otherwise grey areas.
So just carry a tiny pouch of seed bombs when you're out and about, and you'll be ready to leave bright bursts of biodiversity in your wake – no time or effort needed!
How do you use seed bombs?
You don't have to plant seed bombs; just throw them onto some exposed soil as you walk, cycle or drive around, and let mother nature take care of the rest.
Some of the best spots to aim for are places that were created as public flower beds, but have been forgotten about and left unkempt. Neglected street planters, tree beds, roadsides and roundabouts are all great targets for seed bombing. If no one's looking after them, you know that no one's going to come along to strim down your seedlings!
When's the best time to use seed bombs?
Seed bombs work best in spring and autumn, when there's enough rain, and the right amount of sun to help the seedlings grow without scorching them. Wildflowers' sowing windows are generally within these months too.
How do seed bombs work?
The clay holds the ball together until it gets rained on.
Then, once the bomb has met rain and sun, the seeds will begin to germinate as the ball breaks apart. The compost the seeds are encased in helps them get started before they root into the ground, and chilli powder can deter any creatures from nibbling on the seedlings.
How do you make seed bombs?
After testing out countless methods, ratios and ingredients, this is the recipe I personally swear by. These amounts will give you about 50 small bombs.
Things you need
1/2 cup powdered red clay
1 cup peat-free seed sowing compost
2 tbsp native wildflower seeds
1 tsp chilli powder
Large mixing bowl
Optional (but helpful)
Sieve the clay into the mixing bowl (or break it up with your fingers) so it's a fine dust, with as few lumps as possible.
Add the 50ml of water and mix with the clay until it forms a paste-like consistency. IT won't look like a lot of water, but trust me it should be enough! The less wet your mixture, the less messy the process will be.
Now, chuck in the compost and mix the two together thoroughly. This can be tough work, but pushing through the mixture with a fork will help.
Add the chilli powder and roughly mix through with the fork.
Shake in the wildflower seeds and gently distribute them throughout.
If you have time, leave the mixture in the bowl, covered with a tea towel, for around 20-30 minutes (keep checking back to see if it's still malleable). This helps it dry out a bit, so that when you start balling it you'll only get a little residue on your hands rather than having them covered in thick mud!
Take small lumps of the 'dough' and ball it into spheres about 1.5cm wide.
As you make them, pop your seed bombs into a cardboard box. When they're all done, close the lid and leave it in a warm, dry place for 2 days. The quicker they dry, the less likely the seeds are to germinate. If they do start to germinate, no problem! Just make sure you get them out onto some soil ASAP.
And that's it!
If you want to give it a go, you can get all the ingredients you need, delivered to your door, in our Seed Bomb Making Kit.
What about paper seed bombs?
You can technically make seed bombs with paper, but they're less subtle and don't nourish the seedlings or biodegrade as well as clay and compost. And no one wants to be branded a litterer (trust me, been there).
Make bloom not boom ☮️✌🏻