Pinus sibirica seed

Siberian cedar/Pinus Sibirica

The Siberian Pine is a useful ornamental tree for parks and gardens in ares where the climate is cold, growing at a steady rate on a wide range of sites. It is very tolerent of winter cold and wind exposure and is hardy down to at least -60C.

It can grow up to between 30 -40 meters in height with a trunk up to 1.5 meter diameter. It is also long lived with a possible lifespan up to 850 years. Closely related to the
Swiss Pine (pinus cembra)

Seeds of the Siberian Pine have a deeper dormancy than most pine species. This dormancy can be broken down by a period of cold stratification in the fridge.

You can easily do this by first soaking the seeds in water for 24 hours. Fully drain away all of the water and place the seeds in a zip-lock freezer bag. Place the seeds in the fridge, it is important that during this period that the seeds do not dry out or are waterlogged otherwise the pretreatment will be ineffective. Alternatively the seeds can be mixed together after soaking with a 50/50 mix of moist compost and sharp sand to help maintain moisture around the seeds for the pretreatment.

This pretreatment needs to last for between 16 and 20 weeks before the dormancy is broken down and the seeds are ready to be sown. In general many seeds will fail to germinate unless treated in this way, simply sowing untreated seeds in compost at room temperature will not break down the dormancy and germination will be disappointing.

Fill your chosen container with a good quality general potting compost. Suitable containers could be plant pots, seed trays or plug trays or even improvised containers with drainage holes. Firm the compost gently and sow the seeds on the surface. If you are sowing in plug trays, sow 2 or 3 seeds per cell.

Cover the seeds with a couple of millimetres of vermiculite or failing that a fine layer of sieved compost. Follow with a gentle watering and keep them at room temperature. Germination will begin a few weeks from sowing.

The seedlings are reasonably robust and trouble free and usually grow to a height of between 3 and 5 cm in the first growing season depending on the sowing date and cultural techniques. Densely sown seedlings are at risk from fungal diseases such as “damping off” which can cause rapid loss of many seedlings.

Developing seedlings should be fine in full sun, keep them well watered and free of competing weeds. Growth will accelerate in the second and subsequent years and the developing young trees should be re-potted as necessary preferably during the dormant season. After perhaps 3 or more years they are ready to be planted in their permanent position.