Here you can see the leaves in the field tinged with blue.
Sukumo is the composted leaves you start your vat with. The 40 liter vat I made uses 2 kg of sukumo. I use around 8 kg in the pots I normally deal with. To make the sukumo the leaves are collected and piled in a traditional wood and mud wall barn (kura/蔵) with a dirt floor and sprinkled with water and lime. As the leaves begin to compost they generate heat.
Here the compost is covered with burlap.
This process is different from the extraction process most commonly used in India where the fresh leaves are fermented in a high alkili solution to dissolve the indican and then stirred or beaten or actually run around in by laborers to oxidize the liquid which is then allowed to settle, the top liquid discarded, and the end sludge collected as pigment which can then be used in a reduction vat for dyeing.