Seed bombs are an excellent and inexpensive tool for the urban gardener to bring more life to an otherwise dull or neglected area. It can also help support a less than thriving ecosystem, attract helpful insects (bees, butterflies etc.).
Seed bombs are a fun and easy project you can do at home or at school, also, did I mention inexpensive?
Step 1: Materials
Seed Starting Mix
Air Dry Clay (paper pulp or confetti could also be used)
Plastic molds/cookie cutters (optional)
Grab one of Michaels or A.C. Moore's 50-55% off coupons and buy a 10lb box of air dry clay for less than $5. They clay will also last for an extremely long time. If it starts to harden, just add some water and let it become clay again.
Step 2: Locations
Before you engage in your guerrilla gardening activities, you may want to suss out areas in need of a little help and what type of sunlight these areas receive. Plants need sunlight, so throwing a seed bomb filled with full sun flower seeds might not work out in covered public garage. Seed bombs are designed for hard to reach places, so as long as your desired areas have the basic requirements for plants to survive (sun, water, etc.) you should be good to go.
Popular guerilla gardening spots include: schools, playgrounds, tree pits, neglected public planters. The pictures above were taken in Boston's North End right before we received unnecessary April snow.
Step 3: Selecting Seeds
Seed bombs can be made for a variety of purposes, beautifying an area, supporting the local bee population and more! Most people recommend getting seeds for plants native to your area as they'll be most likely to survive in your climate and won't be considered invasive. Usually the seeds you find in your local stores are appropriate for your region.
Step 4: Make!
The main purpose of clay is to hold the soil and seeds together and to prevent wildlife from eating the seeds. When you throw your seed bomb, the clay will start to break down as it comes into contact with rain etc. The seeds will start to germinate and as they get bigger, the plants will help break down more of the clay.
5-1-1 seems to be a good ratio for most things. So in a bowl or bucket, mix 5 parts clay with 1 part soil and 1 part seed. Water will be your supporting binding agent, adding in small amounts until you are satisfied with the consistency. Take a small clump of the mixture and roll into a ball in your hands.
An alternative method to try is not mixing the clay in with the soil and seeds. Mix the soil and seeds with a little water to moisten. Press out a couple of flat pieces of clay and add soil and seeds to the center. Fold the clay around the soil and seeds and then roll out the seams.
Let the bombs dry for a few days before you use them.
Step 5: Throw!
When you your bombs are ready, go out to your predetermined spot and throw! That's all you need to do, just throw the seed bomb and leave it to it. You don't need to plant, bury, or cover the ball with anything.
Check back periodically to see how things progress.