You can have crops ready for the table weeks in advance by growing under the cover of poytunnels and glass
Polytunnels and greenhouses
Greenhouses and polytunnels can be very valuable additions to allotments, but raise problems. They can be scruffy if home-made from scrap materials, and may be left derelict when, as often happens, their owner moves. With time, glass gets broken and plastic degrades and is dispersed by the wind. Because of this, many allotments ban structures over 1m (3ft) high, or require plans to be submitted for approval.
On a practical note, in summer, crops under cover need attention almost every day, and without taps and electricity, it is hard to tend them properly. One way round this is to have shared polytunnels or greenhouses, where the allotment society buys and maintains a tunnel, letting space within it to tenants.