Heat-Resistant Varieties of Spinach

Types

• When selecting varieties of spinach to sow in your vegetable patch, seed catalogs or print literature may refer to spinach as being heirloom or modern-bred. Heirloom spinaches are genetic varieties used generations ago, often prior to 1930. They may develop richer leaf flavors, but they tend to have limited tolerance to the warming conditions of late spring and early summer. They bolt quickly or may be more susceptible to disease. Modern varieties demonstrate more resilience to warm soils and warm weather, but too much heat still leads to bitter-tasting leaves and bolting.

Planting

• Spinach grows quickly and produces leaves worthy of picking anytime from 30 to 70 days after sowing seeds. These maturation times differ among spinach varieties, and the plants rejuvenate with new leaves after being cut back; heat-resistant types continue to grow longer into late spring and early summer. Sow all spinach in crumbly, fertile, moist but well-drained soil in early spring or very late summer. Light frosts do not harm spinach.

Germination Insight

• Even though heat-resistant spinach varieties are slow to bolt during warm weather, their heat-resistance does not extend to their seed germination requirements. All spinaches sprout best when soil temperatures are lower than 80 degrees Fahrenheit, which makes planting a crop for fall more challenging. Sowing spinach seeds in early spring supplies the proper cool temperatures for sprouting. If planting in August or September, chill the spinach seeds in the refrigerator for two weeks before sowing. Shade the garden soil to keep it cooler until seeds sprout if late summer/early fall weather is unusually hot.

Alternatives

• Some gardeners, especially those in mild winter and hot summer regions, only sow spinach in late winter for a nice crop yield across the spring months. Instead of battling against the heat of summer and trying to get spinach to last longer, other spinach-like vegetables are grown in summer. Malabar spinach (Basella alba) and New Zealand or everlasting spinach (Tetragonia tetragonoides) are not true spinaches, but grow well in the hot weather, humidity and warm soils common to the summer vegetable patch. Their leaves taste like those of Spinacia oleracea.