Culture: Spinach does well with a combination of cool weather, short days, high soil fertility, ample water, and neutral pH (6.5-7.5). Sprinkle some limestone in the row as you plant if you think the soil is too acidic. Sow seed 1/2 in. deep directly into the garden as soon as the ground can be worked, and thin to 4-6 in. apart in rows 8-10 in. apart. Succession plantings can be made every 2 weeks. Temperatures above 60 degrees F for the first 6 weeks of growth may increase the tendency to bolt. Mulch the soil to reduce bolting by keeping the roots cool. As spring heats up plants get smaller and less sweet and bolt faster.

Fall Planting: High summer temperatures can kill small seedlings, so wait until a month before first fall frost to sow. Fall plantings give a more sustained harvest than spring plantings. Spinach grown in frosty weather has the largest and sweetest leaves. Some varieties tolerate 0 degrees F and over-winter to produce excellent spring crops.

Pests: For fall crops, sow seed 2-3 times as thick to help spinach survive grasshoppers.

Seed Savers: Grow only one variety or isolate by 1/4 mile for home use. For pure seed isolate by 1/2 to 1 mile.




Japanese Spinach
Link to heat tolerant varieties: http://www.kitazawaseed.com/seeds_spinach.html

Oriental Giant

'Oriental Giant,' an extremely fast-growing hybrid spinach bred in Japan, has amazing vigor and quickly produces giant leaves that are at least double to triple the size of other spinach varieties. Plan on truly bounteous harvests, because 'Oriental Giant's big and smooth, slightly arrowhead-shaped leaves produce their huge yields almost overnight. 'Oriental Giant' has excellent mild and sweet flavor, rich green color and a succulent crunchy texture. This fine variety has outstanding disease resistance to downy mildew, races 1-4. Wait until plants are well established and harvest just the outer leaves, leaving at least 4 younger center leaves so plant will continue to grow. Water and fertilize after cutting and plants will provide 2 or 3 pickings before weather gets too warm and spinach begins to go to seed. Plant again in late summer to early autumn for a succulent autumn harvest. - edited by dtd pbcouchman — http://www.digthedirt.com/plants/37981-spinach-spinacia-oleracea-oriental-giant