High Tech Seed Cleaning
Low Cost Alternatives
Initial Steps in Seed Preparation
• Adapted seed source (Often local)
• Locate mature flowering plants of desired
species
– Flowering in the spring is the first sign there
will be seeds to collect.
– Can make preparation to grow plants if we
know we will have seeds.
Initial Steps in Seed Preparation
• Monitor seeds as they are maturing and at
harvest
– Will there be enough for our plans ?
– Is the quality good enough to collect ?
• Are there good seeds ?
• Are they mature ?
– Need to know seed structure
– Cutting test or pinching is an option to evaluate seeds in
the field
After collection Before cleaning
Fruit type
How
handle?
Examples
Moist and
fleshy
Dry and can Dry but
be dried
must not
dry
Keep cool Keep cool Keep cool
Keep moist Allow to
Do not
dry
allow to dry
Juniper,
Most seeds Big leaf
dogwood,
maple
plum
After collection terms
• Keep Cool: If you would be hot then your seeds
are hot. Do not let your seeds feel hot.
• Keep Moist: keep fruit from drying and becoming
hard, but do not let it ferment – ventilate.
• Allow to dry: put up on racks in thin layers (1
inch) where air can reach seeds.
• Do not allow to dry: must keep in sealed container
(plastic bag) or a damp location or water.
Steps in cleaning
• Extraction: remove seeds from fruits
• Clean: remove trash from seeds
• Upgrade: eliminate additional trash, bad
seeds
• Prepare for storage
Extracting fleshy fruit
• Fruit must be soft enough to crush easily
with your fingers
– Water soak will soften
• Can take 1 to many days or a week or more
• Must change water daily to prevent fermentation
– Extraction will damage seeds if fruit is not soft.
• A juicer will macerate fruit
• Wash pulp away on a screen
Extracting dry fruits
• Dry fruit that opens (cyprus)
– Must give room for fruit expansion
– Shake fruit to remove seeds
• Dry fruit that does not open (mt mahogany)
– May require breaking fruit open (pods)
– Fruit may be the “seed” and require only drying
Drying fruits
• Open air drying on screens or sheets will
work
– Air movement over the seed will help
– Seeds must be in thin layers and turned often
• A seed dryer may help
– Easier drying
– Faster drying
What is a seed drier?
• Two boxes
– Screen-bottomed top box holds the seeds
– Bottom box has a fan to force air through seeds
– Boxes fit tightly together so little or no air
escapes except through the seeds.
• Device that dries seeds quickly, easily,
uniformly
When will seeds and fruits dry?
• Relative humidity usually less than 30%
• Heat may be needed to dry the air
–
–
–
–
When to add heat?
How much heat is needed?
Should never use heat above 110oF
Psychrometric table is our guide
Cleaning
• Seeds from fleshy fruits need drying
• Some dry seeds may need appendages
removed
– Tail on mountain mahogany – leather gloves
– Wing on pine seed – rubbing board
– Cotton on willow or aspen – vacuum cleaner
Cleaning - Screens
• Types of Screens
– Hardware cloth of different sizes
– Purchase hand screens (come in many sizes)
– Soil sieves very small seeds (aspen)
• Trash over/seeds through: sclaping
• Seeds over/trash through: sieving
• Separate by diameter or thickness, not
length
Cleaning - air
• Pour seeds out in front of a fan
– Lighter particles fall farther from the fan than
do heavier particles
– Work best with larger seeds
• Vacuum trash up from seeds on a screen
– Spread seeds out in a layer one seed deep.
– Come down on seeds slowly with vacuum,
stopping when trash is lifted up.
Upgrading
• Hand pick trash
• Water floatation
– Seeds float and trash sinks
– Trash floats and seeds sink
– Use a sieve or drink bottle
• Fan to blow out empty seeds.
• Check seeds to see if full
– Thin seeds on a light table
– Some can be pressed lightly
– Cut a few
Preparing for storage
• Dry the seeds over night on a drier or in a
dry room
• Seal in plastic bag or bottle to protect from
moisture
• Not need this step if sowing seeds in a few
weeks.