Spinach Viking Seed Tapes (Aimers Seed Tape) Heirloom Vegetable. This dependable heirloom spinach produces a heavy yield of glossy, tasty dark green savoyed leaves that are rich in vitamins.  Viking is a long standing variety that shows good heat tolerance. Harvest of mature leaves can be expected about 50 days after planting. Baby greens can be harvested at about 20-30 days. Introduced in 1933.