The growing season of spinach can be extended by overwintering plants to provide a spring crop long before a seeded crop is ready to harvest. The key is to grow the plants to the right size-10 centimetres in diameter; height will vary depending on type-before the coldest weather arrives. Plant four to six weeks before the date of your first hard fall frost and sow as you would spring and fall crops, providing the plants with all their needs to keep them growing steadily. Savoy types generally overwinter better than smooth-leafed varieties. ‘Bloomsdale Dark Green', ‘Giant Winter', ‘Tyee' and ‘Melody' are recommended.
In regions where winter temperatures fall below –7°C, mulch with a 7.5- to 10-centimetre layer of shredded leaves, straw or hay when the soil freezes. Use 15 centimetres in areas with severe winters. Where winters are more mild, especially when there is also a lot of rain, don't mulch or the plants will rot.
In spring, about the same time you sow your first spring spinach crop, pull back the mulch and side-dress the plants with compost. Allow the plants to start to grow again before beginning to harvest.
Diseases and pests
Good gardening practices help reduce problems with diseases and pests. Build up your soil with compost and supplement poor soils with organic fertilizer. Do a thorough fall cleanup and use a three-year crop rotation. To discourage moulds, don't water in the late afternoon or evening. When removing diseased plants, remember that they must be destroyed, not composted.
Downy mildew: Leaves have yellow spots with fuzzy, purple growth on the undersides. Purplish lesions then form on leaves and stems, which become covered with a downy, white fungus. Plants soon die. Remove infected plants.
Spinach blight: Leaves turn yellow and curl; plants are stunted. Remove infected plants. Blight is spread by aphids, so control the population (see Aphids below).
Fusarium wilt: The disease is generally carried in the soil. Plants turn yellow and wilt. A brown discolouration appears in the veins. Remove infected plants.
Mosaic viruses: Leaves are mottled and plants are stunted. Most viruses are spread by aphids, so control population (see Aphids below). Remove infected plants.
Leaf miner: Leaves develop irregular, light tan tunnels or blotches. Inside the blister-like area are droppings and maggots, which are the immature stage of a fly that lays its eggs on the undersides of the leaves. Pick infected leaves. Where leaf miners are a serious problem, cover the bed with a row cover after planting the seeds. Spinach that matures late in the fall, over the winter or very early in the spring may escape damage.
Flea beetle: Tiny, jumping black beetles pock the leaves with small holes. A heavy infestation can destroy young seedlings. Cover the bed with a row cover after planting the seeds.
Aphids: Leaves curl, pucker and become stunted. Aphids are visible on the undersides of young leaves. For light infestations, spray plants vigorously with water in the morning, every other day, for a total of three times. For heavy infestations, apply insecticidal soap, getting underneath the leaves. Repeat every three days until aphids are under control.
‘7-Green' (40 days) Plain, moderately bolt-resistant, full downy mildew protection; can also be sown in summer.
‘Bloomsdale Dark Green' (‘Bloomsdale Longstanding Dark Green', 50 days) Savoy, good for overwintering.
‘Bloomsdale Savoy' (50 days) Savoy, good for overwintering.
‘Giant Winter' (55 days) Semi-savoy, a special variety for overwintering; can also be sown in summer.
‘Melody' (45 days) Semi-savoy, tolerant of downy mildew and cucumber mosaic virus, bolt-resistant.
‘Olympia' (45 days) Smooth, long-standing (four days longer than ‘Melody' or ‘Tyee'), tolerant of downy mildew; can also be sown in summer.
‘Skookum' (45 days) Semi-savoy, tolerant of downy mildew. Can over-winter in coastal British Columbia.
‘Space' (40 days) Smooth, bolt- resistant, tolerant of downy mildew. Can also be sown in summer.
‘Spargo' (40 days) Semi-savoy, bolt- resistant. Can also be sown in summer.
‘Tyee' (45 days) Semi-savoy, most bolt-resistant savoy type. Tolerant of downy mildew and cucumber mosaic virus; good for overwintering; can also be sown in summer.
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