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Fun and easy to make, seedbombs can be used to green up hard-to-access urban wasteland or in your garden at home
Seedbombs originated in seventies New York. The term was originally 'seed grenade' and comprised wildflower seeds, water and fertilizer all wrapped up in a condom. They were lobbed over fences onto empty lots, with the overarching aim of making neighbourhoods sprucer.
From these small beginnings grew the guerilla gardening movement itself, where vacant lots were turned into productive community gardens with vegetables and edible flowers on tap.
However, seedbombs are not just for guerilla-style gardening - they can also be used for planting at home. And thankfully, the art of making seed bombs has moved on since the seventies.
Josie Pearl Jeffery, who runs Seed Freedom, a Sussex-based company that specialises in seedbomb kits, holds workshops at gardening events and summer festival.
'Seedbombs have the protection provided by the outer coating of earth and clay and as such the seeds are less likely to be damaged by harsh weather conditions and eaten by insects, birds and rodents,' she says.
The seeds therefore have a better chance of germinating and growing into mature plants - which means fewer seeds are required because the rate of success is higher.
So that's the reasoning behind it, but what's the method?
How to make a seedbomb
Having attended one of Josie's workshops I can tell you how the seed bombs take shape:
1) Mould your clay and compost mixture with water until it is sticky.
2) Add your seed mixture, which can be salad or mixed wildflower seeds, for example, and then pat gently into a small ball around the size of one you'd use for ping-pong.
3) Once you have chosen an appropriate site you can push your ball into place - in a pot/a wall/window box etc.
4) Then ensure it is kept warm (try to avoid frosts) and moist with regular watering until the seeds start to germinate.
If you prefer to adopt the guerilla gardening approach and throw the seedbomb onto some derelict land what will happen?
Josie explains that there are two different outcomes which depend on the weather. The seed bomb will either keep its form and the seeds germinate and sprout from the ball and work their way out of it in time, or if it rains a lot the seedbomb dissolves and seeds will lie on the bare earth until they germinate either on the surface of the ground or get trampled.