Plants can bolt or prematurely run to seed if they receive a check to their growth. In crops such as spinach this is likely to be due to dry soil conditions. In the case of beetroot, cabbage, carrots, celery, garlic and onions it is more likely to be temperature related.
Most plants of our temperature zone need a spell of comparatively low temperatures during their period of active growth or they cannot produce flowers and seed. Some weather conditions have effects upon plant growth which are beyond our control and Vernalization is one such effect. Even so it may sometimes appear that the seed at fault, especially when a variety which is described as being less susceptible to "bolting" has been grown.
When we use the term Vernalization in regard to "bolting" or prematurely running to seed, we infer that the weather pattern has induced the plant to accelerate growth and seed production because the seed stimulus has come at the wrong time. The ability of the plant to react to climatic conditions in this way can apply even to comparatively young seedlings and at almost any later stage in growth. All that is necessary to upset normal development is a short spell of cold weather after seed germination which will vernalize the plant and instead of beetroot producing an edible root, it will develop a flower and seed-head, or a cabbage will fail to heart and run to seed in the same way.