Spinacia oleracea

Spinacia oleracea is a ANNUAL growing to 0.3 m at a fast rate.
It is hardy to zone 5 and is not frost tender. It is in leaf all year, in flower from June to September. The species is dioecious . and is pollinated by Wind. The plant is not self-fertile.
Suitable for: light , medium and heavy soils. Suitable pH: acid, neutral and basic soils. It can grow in semi-shade or no shade. It prefers moist soil.

Plants grow best and produce their heaviest crop of leaves on a nitrogen-rich soil. They dislike very heavy or very light soils. They also dislike acid soils, preferring a neutral to slightly alkaline soil. Plants require plenty of moisture in the growing season, dry summers causing the plants to quickly run to seed. Summer crops do best in light shade to encourage more leaf production before the plant goes to seed, winter crops require a warm dry sunny position. Young plants are hardy to about -9°c. Spinach is often cultivated for its edible leaves, there are some named varieties. These varieties can be grouped into two main types as detailed below:- Forms with prickly seeds. These are the more primitive forms. Their leaves are more lobed and they are in general more cold tolerant and also more resistant of summer heat. They were more often used to produce a crop in the winter. Forms with round seeds have been developed in cultivation, These have broader leaves, tend to be less cold hardy and were also more prone to bolt in hot weather. They were used mainly for the summer crop. Most new cultivars are of the round seeded variety and these have been developed to be more resistant to bolting in hot weather, more cold tolerant, to produce more leaves and also to be lower in calcium oxalate which causes bitterness and also has negative nutritional effects upon the body. Some modern varieties have been developed that are low in oxalic acid. Edible leaves can be obtained all year round from successional sowings. The summer varieties tend to run to seed fairly quickly, especially in hot dry summers and so you need to make successional sowings every few weeks if a constant supply is required. Winter varieties provide leaves for a longer period, though they soon run to seed when the weather warms up. Spinach grows well with strawberries. It also grows well with cabbages, onions, peas and celery. A fast-growing plant, the summer crop can be interplanted between rows of slower growing plants such as Brussels sprouts. The spinach would have been harvested before the other crop needs the extra space. Spinach is a bad companion for grapes and hyssop.