Update #15: Preparing seeds of Pinus nigra, Pinus peuce and Abies alba for planting / April 11, 2023

This year we are focusing on improving and scaling up our tree nursery in Fushë Lurë. We are processing seeds to grow 11 000 seedlings, and we want to share details about this process.

Our tree nursery has been a long-term goal of Trees for Lurë. By producing our saplings, we will be able to reduce the cost of our reforestation efforts, but mainly - we will be allowed to plant at the highest protected area of the Lurë National Park.

We established our tree nursery in 2022 and tried to grow 5 000 Pinus nigra seedlings. We learned a great deal from this effort, but the results are not good enough, with no more than 1 000 seedlings surviving the 1st year.

The results were not as good as we hoped due to errors we made through out the year so this time we’re implementing many changes in the nursery to improve our results.

It all starts with the seeds

Growing seedlings starts (as with any plant) with the seeds. The seeds for our trees were collected by the local team in 2021 (Pinus nigra) and 2022 (Pinus peuce, Abies alba). The seeds are collected manually in the Lurë National park.

Seed collection & extraction

The seeds have been extracted from the cones exposing them to warm temperatures and manually working the seeds out from the cones. Unprocessed seeds are stored in Lure in a dry, cold area in cloth bags.

Cleaning & sorting seeds

After the winter, we collected the seeds from Lure and started processing them. Cleaning is the first step, and its goal is to sort out residual remains of the cones, remove the “wings”, and, most importantly, separate the healthy or “full” seeds from the dead or “empty” ones. The goal is to achieve the highest possible percentage of healthy seeds to minimise costs in the nursery when growing the seedlings.

For Pinus nigra and Pinus peuce the process of cleaning seeds is the mechanical removal of the wing and the seed crown. The waste material is then separated using precisely directed airflow (fancy words for using a hair dryer). Separation of the healthy seeds is done using airflow and uses the fact that healthy seeds are much heavier than dead ones. Using this method, we managed to clean Pinus nigra from the initial 37% to 76% of healthy seeds. Due to the small amount of Pinus peuce we decided to stratify and germinate all the seeds and do only basic cleaning.

Abies alba must be handled gently as the seeds are coated with resin which must remain on the seed. Therefore, we have just removed the wing mechanically and separated the seed from the waste by the trusty hair drier. As the healthy seeds were at 66% we did not attempt to sort the seeds more.

Stratification - breaking seed dormancy

Seeds which are collected or purchased are dormant - they sleep. To wake the seeds up for germination, they must go through the cold stratification process. This process simulates the spring cold and wet conditions in nature, waking the seeds up.

Stratification starts by soaking the seeds in the water for 24 hours at a temperature of 3—5℃, regardless of the species.

When initial soaking is done, water is, drained and the seeds are kept wet at 3—5℃ for up to 30 days in the case of Pinus nigra, 210 days for Pinus peuce and 60 days for Abies Alba.

It is essential to monitor the seeds, prevent them from drying, and maintain the temperature.

Next steps

We started the stratification process on 6th of April, which means that Pinus nigra seeds will be ready around 10th of May, and we will plant them. Abies alba will be prepared a month later at the latest.

While seeds are undergoing the stratification process, we’re working on many other tasks in the nursery, such as building greenhouses, preparing soil and growing systems.

On behalf of the whole team,
Pavel