Asparagus doesn't grow during the winter. All of the above ground shoots die after the first frosts, and new shoots sprout the following spring. Sowing in early spring is probably the best time for starting from seed, but you will get usable shoots much sooner if you plant small roots, which are readily available at garden centres.
If you wish to grow asparagus from seed it will take 1 year longer before you harvest the spears compared to growing from crowns. Even with crowns it is recommended that you do not harvest the spears until year 2. This link may help...... http://www.bbc.co.uk/gardening/basics/techniques/growfruitandveg_growingasparagus1.shtml If you buy seed you will get male and female plants. It is recommended that if you see the red berries which indicate a female plant that you remove these plants. Male plants are more productive. http://www.gardenaction.co.uk/fruit_veg_diary/asparagus-seed.asp http://www.allotment.org.uk/vegetable/aparagus/index.php