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Wild Flower Fellowship

Seed Drying – an extremely important part of the process

Published by lucy grove on Fri 09 September 2016
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I’ve quickly learnt that harvesting seeds is very much only the start of the process. Instinct will tell you that freshly collected seed is likely to need some preparation before storage and that storing seed wet is not a good idea. As soon as a seed is harvested we started the drying process. You don’t want to keep newly harvested, unprocessed seed in bags, as the living plant material will continue to respire and result in decay. There is also a second stage of decay that would occur if drying was delayed, due to the respiration of the resulting microbial action. Temperature increases the rate of respiration (for every 10°C increase in temperature there is roughly a doubling in the rate of respiration). Therefore ensuring the seed does not heat up too much is also important.  

Freshly unloaded harvest needing to be dried before it heats up too much
Freshly unloaded harvest needing to be dried before it heats up too much

 

Drying seeds collected at home from the garden, or on wild forays, is relatively simple. However on the scale undertaken on Emorsgates’ farms, processes need to be scaled up somewhat. Large tarpaulins are laid out in the sun and freshly harvested seed is unloaded from the trailer. Then the raking begins – lots of raking! Getting the seed into as thin a layer as possible will aid drying and speed up the process. Then throughout the day the seed needs to be turned to ensure all the seeds are dry. Like any other farming, the weather has the controlling hand of when seeds can be harvested and when and for how long seeds need to be left drying. I’ve quickly become an ardent weather watcher, checking the forecast, checking the skies, and on more than one occasion running for the tarpaulins when I’ve felt a speck of rain!

I really enjoy the raking of the harvest with this lovely yellow rake!
I really enjoy the raking of the harvest with this lovely yellow rake!

 

 

There is lots and lots of seed to dry
There is lots and lots of seed to dry

 

Properly dried seed, if stored in the right conditions, can remain viable for many years. In nature this is an important strategy for many plants.  Nestled down in the soil are living bank of seeds, little capsules of potential just waiting for the right conditions to allow them to germinate and grow. This is often most noticeable in newly cleared areas of woodland. Following the opening up of the woodland canopy and the associated increase of light, foxgloves emerge in great carpets – their seeds having laid dormant in the soil for years.

I quickly found that some seeds need more careful drying than others. The Woolly thistle seeds were dealt with using pitch fork and gloves.  The Orchid harvest on the other hand needed a much more gentle approach. With thousands of tiny, dust like seeds bursting from each capsule, any turning that is too vigorous or any gusting wind, would see the seed puffing into the surrounding air and being lost from the harvest.

Bagging up the dried woolly thistle seed heads
Bagging up the dried woolly thistle seed heads

 

These orchids will need a lot more drying before we can collect the seed
These orchids will need a lot more drying before we can collect the seed

 

After drying the harvest, the seeds then go on be further processed- removing any non-desirable seeds from grassland mixtures or sorting the seeds into pure form to be distributed to Emorsgates’ clients. This all happens in Norfolk – and I will be following the seeds there shortly!