what are seedballs?
Seedballs are 10 to 20 mm diameter models of the living world, containing the seeds for a wild or domestic ecosystem. A lot of different seeds can be used to make seedballs, and mixed together with local soil, your own compost, some sand, clay and water they become little potential gardens. They are cost effective and can be made by anyone, anywhere where there is soil and seed.
Much less seed is used than in conventional growing, resulting in fewer plants which are smaller but stronger with a higher yield. The technique is useful for seeding thin and compacted soils, and avoiding seed eaters.
It is an ancient technique that was re-introduced by Masanobu Fukuoka, an advocate of natural farming.

what do you need to make seedballs?
- Local, native seeds
- red clay
- (homemade) humus/compost
- local soil

how to make seedballs?
On the internet you can find many recipies to make seedballs. They all differ slightly, mostly in the proposed proportions of ingredients. This is how we did it:

We use 1 part of seeds, in this case a mix of native wild flowers and herbs called Tübinger.
The Tübinger-seedmix is benefiicial for pollinating insects, in special for the honey bee. It consists of 10 annual flowering plant species in different proportions :
borage, buckwheat, marigold, white mustard, coriander, caraway, centaurea jacea, cheeseplant, dill and phacelia.
We mix the seeds with three parts of (dry) humus from homemade compost. If the compost is half ripe, it needs to be sifted to eliminate the lumps.
Than we add five parts of (dry) local soil and we mix the whole with two parts of red clay mixed with water. We add water gradually and mix all ingredients until a firm consistency is reached. Than we can pinch off wet soil from the main mass and roll it between the palms of the hands into smooth and round balls of 10 to 20mm diameter.

Finished seedballs must dry undisturbed for approximately 24 hours. Once the seedballs are dry they may be stored in a cool dry place, or you can broadcast them immediately in public wastelands or parcs - doing some seedbombing activism!
Seedballs don’t need to be burried or watered. They can lay dormant in place until released by rain. No matter where a seedball has landed, something from the mix inside will be at home on the spot, so all possible habitats are covered into one broadcast application.
In 4 to 6 weeks, the wasteland will change looks and become a flowered meadow!

Tubinger and Brandenburger seed-mixes
Phacelia seeds are the main component in the Tübinger seedmix. Sequential sowings of the Tübinger-seedmix provide nectar and pollen from early summer to late autumn and fill the gaps when food for pollinators becomes scarce.
The flowers attract a diversity of visiting insects, including the honey bee and many species of bumble bees. Different insect species are favoured by different plant species.
Bees play an important role in pollinating plants, and are the major type of pollinator in ecosystems that contain flowering plants, vegetables and fruittrees.
It is estimated that one third of the human food supply depends on insect pollination, most of which is accomplished by bees, especially the domesticated European honey bee.
Many bees are opportunistic foragers, and will gather pollen from a variety of plants, while others are oligolectic, gathering pollen from only one or a few types of plant.
Honeybees live in a matriarchal society. The group consists of a mother and her daughters. The mother is considered the ‘queen’ and the daughters are ‘workers’.

guerilla gardening
Seedballs and seedbombing are perfect tools to put guerilla gardening into practice. Guerrilla gardening is political gardening, a form of direct action, primarily practiced by environmentalists. It is related to land rights, land reform, and permaculture.
Activists squat an abandoned piece of land which they do not own to grow crops or plants. Guerrilla gardeners believe in re-considering land ownership in order to reclaim land from perceived neglect or misuse and assign a new
purpose to it.

info on seedballs and guerilla gardening
http://en.wikipedia.org/wiki/Seed_ball
http://en.wikipedia.org/wiki/Guerilla_gardening
http://en.wikipedia.org/wiki/Permaculture
http://libarynth.org/permaculture
http://libarynth.org/urban_permaculture_concepts
http://brussels-farmer.blogspot.com/
http://thoughtsandtalks.so-on.be/2010/03/25/tubinger-seedballs-for-diversity-graz/
http://thoughtsandtalks.so-on.be/category/ecology/city-honeybees/