This activity is suitable for use at those parts of the year when seeds will germinate outdoors usually April – June in the UK but do check the labels of the seed to be used. Two recipes are given. The traditional
clay ball and a flour and compost ball which avoids the need to order clay.
At schools I normally make seedballs in groups of three with each child making three balls to take away at the end of the session. However,
if the plan is to seed bomb a school garden each student may only make one bomb and the bombing will take place in small teams with each team bombing a marked off section of the garden. When the seeds have germinated the students can see
how effective they have been in covering the whole of the target area.
Costs of 100g of wild flower seed will cost about £20 -£26. The number of seeds per gram will vary considerably depending the
plants in the mix e.g. a gram of Yellow 20 1 g of Flag iris will contain approximately 20 seeds while 1-gram Common centaury (Centaurium erythraea) will contain approx. 80,000 seeds. Seeds of common garden flowers can be colected for free
and used immediately or be saved to be sown next year.One of my favourate plants for this activity is the Poppy as seeds can be easily collected and saved.
The compost used in this activity can be purchased
from the local garden centre, but it is better if homemade seed compost is used as this will demonstrated a use for the compost produced from the kitchen ,fruit and garden waste. Follow the link to find a recipe to make seed and potting compost Seed & Potting Mixes
It saves time and wastage if the teacher/trainer has weighed the seed in advance and dispensed
them into containers or has provided pre-marked plastic measures. I have modified the quantites used in the activity below for use with common kitchen measuring spoons
60g (1/4 cup) of cheap flour,
125g (1/2 cup) compost,
2.5 ml (1/4 tsp) seed
Plastic measuring scoops/measures 1/2 cup, 1/4 cup, 1 tsp (5ml), 1/2 tsp (2.5ml)
A mixing bowl or plastic "take away" container
Grease proof/wax paper or kitchen towel for
drying the seed balls
Disposable vinyl gloves and plastic apron (optional)
Measure out 125g of compost and mix in 125g of flour. Stir in
2.5ml of seeds and mix well.
Stir in 5ml of water and mix first with the lolly stick and then by hand. Continue mixing until the mixture can be formed into a ball.
roll into 8-10 seedballs the tps measure can be used to measure the size
Put the balls on the tray or take-away container and leave to air dry for at least a day
The seedballs can be put dropped or thrown onto
the area being seeded. If thrown these flour seedballs are more likely to break up on impact with the soil than those coated in clay and are best thrown immediately after a shower or when rain is expected.