Organic Colorado Blue Spruce Seeds (Picea pungens f. Glauca)

Organic Colorado Blue Spruce (Picea pungens f. Glauca)

When growing from seed the degree of intensity of the silvery blue colour will vary between individual seedlings and a range of seedlings varying from grey green to bright glaucous blue is usual.

A native tree to South-western N. America and the  Rocky Mountains it is now cultivated in many parts of the temperate world. It cannot grow in the shade and must be grown in an acid soil. It withstands strong winds and mountain exposure very well but is not suitable for planting close to the coast. It also cannot tolerate atmospheric pollution.
 

Colorado Blue Spruce seeds are relatively easy to germinate and grow. The dormancy within the seed is short and easily broken and reasonable success can be expected even when seeds are sown without any form of pre-treatment. The benefit of  a short period of pre-treatment is that a greater percentage of seeds will germinate and the germination of the seedlings will be syncronised with most seedlings germinating within a few days of each other.

The pre-treatment is done as follows.

Soak 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 pre-treatment will be ineffective.

t is important to keep checking the seeds every week or so to make sure that they are not drying out. You could also at the start of treatment incorporate a little damp vermiculite or perlite, this helps to keep the seeds moist but not waterlogged.

After around 4 weeks under these conditions the seeds are ready to be sown.

Seeds should be sown into containers filled 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 millimeters 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 within a 10-14 days of sowing.

The seedlings are reasonably robust and trouble free and usually grow to a height of between 2 and 10 cm in the first growing season depending on the sowing date and cultural techniques.

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 2 or 3 years they are ready to be planted in their permanent position.