Spring Onion 'North Holland Blood Red' Seeds 300 Spring Onion 'North Holland Blood Red' Seeds £2.00 Out of stock. Spring Onion 'North Holland Blood Red Allium cepaSow: April to August Harvest: May to October Height: 25cm Fantastic all-rounder. In our opinion, the finest Spring Onion with fantastic flavour and a little heat. Can be left in the ground to produce a full size Onion. Sowing instructions: Direct sow in late April when the soil has warmed a little; can be sown in March undercover. Sow thinly in rows 15cm apart. Growing instructions:Sow every 3-4 weeks throughout the growing season.