Seedballs, Seedbombs or earth balls are used for “seed bombing” where the balls are thrown or dropped by hand  or from the air into the area where they are to germinate .

Sowing Seedballs directly in the field was a technique used in ancient Egypt and by North American First Nations’ tribes and is now being used  for the large-scale regeneration of land.  

Seedballs dropped from the air usually contain the seeds of trees to create forests while those thrown by hand  are often used for planting wildflowers in abandoned vacant and neglected areas of towns and cities. They also provide a means of sowing wild flowers in school grounds and allotment sites.

Clay based Seedballs

The conventional Seedball is  made by  rolling the  seeds in a ball of  compost which is coated with a layer of  wet clay  or,  in a variation of the method, the seeds, compost and clay are all mixed together when making the ball. The compost and clay act as a carrier for the seeds so they can be thrown into inaccessible areas. Each seed ball provides the seed(s) with a mini ecosystem. Where the balls are made commercially, they are normally about a 1cm in diameter a size which makes scattering, but home-made versions tend to vary and are often larger.  The clay provides a  shell   protecting the seed and nutrients  in the compost from  predators e.g.  as birds,  ants and rodents.   However, as this technique  will normally require the purchase of clay there is an alternative  suitable for allotment sites and schools using flour instead of clay. 

The completed balls  are then placed, or more often thrown, into the garden or  ground where it is hoped the plants will grow. There are techniques where the seeds are spread form aircraft, but my view is that this is unlikely to be used on  allotments or school grounds and  domestic gardens, so no further details are given here.   Seedballs can also be used for planting in pots and raised beds.  The seeds will remain dormant until their environmental needs are met. When enough rain has permeated  the clay, the seeds germinate with the initial growth of the plant being helped by the nutrients and minerals in the compost.  After about three weeks the first seedlings work their way through the seed bomb and root into the ground below.  As they grow the seed bomb begins to dissolve.

There are variations to the basic recipe one used by  Seedballs (https://www.seedball.co.uk/ ) are made with the addition of  chilli to help protect  the seed from predators.

Choosing Seed Mixes:
If planning to create a wild seed meadow it is important to choose the right seed mix and to prepare the land first. (Most specialist wild seed suppliers offer advice e.g. https://www.wildflowershop.co.uk/Info%20&%20Advice/meadow%20creation.htm

 https://hub.suttons.co.uk/childrens-corner/how-to-make-seed-bombs

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. The use of measures speed the activity enabling one composter to dispense compost , flour and seeds into the pots for mixing.

Flour Seedballs

1/2 cup compost,

 1/4 cup of flour,  

 1/2 tsp seeds (or 1/4 tsp if the seeds are  very small)

Equipment

Plastic measuring  scoops/measures 1/2 cup, 1/4 cup, 1 tsp ), 1/2 tsp  or  1/4tsp for very small seeds

A mixing bowl or plastic "take away" container for each person

Lolly sticks for mixing the compost, flour and seeds

Water 

Plastic  trays to contain spillage

Grease proof/wax paper or kitchen towel   for drying the seed balls

Cardboard egg boxes if seedball are being taken from the site

Disposable vinyl  gloves and plastic apron (optional)

 Method

Measure out 1/2 cup of compost and mix in 1/4 cup  of flour. Stir in  1/2 or 1/4 tsp of seeds and mix well.

Stir in 1tsp of water and mix first with the lolly stick and then by hand. Continue mixing until the mixture can be formed into a ball. It may be necessary to add  up to three teaspoons of water if the compodst is dry. The mixture should change colour from grey to brown when squeezed

Divide  and roll into 8-12 seedballs. The 1tps measure can be used to  measure the size 

Put the balls in the egg 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. They are best thrown immediately after a shower or when rain is expected.

1. Wearing the gloves weigh or measure  the 25g seeds and the 200g compost  into a bowl or plastic container
2. Gently mix the seeds and compost with a spoon or by hand.
3. Add the dry red  clay and mix again.
4. Slowly add water while continuing to  stir and mix  the seeds, compost, and water to form an evenly mixed  paste.
5. Line the  plastic tray with wax paper
6. Hand roll the material containing the seeds,  compost and  clay into a ball of about 25mm in diameter 
7. Put the seed balls on the tray and allow to airdry for at least a day.  If the seed balls are to be taken away from the session before they are dry gently wrap them in the wax paper to air dry at later.

Once the balls are dry throw