When space is at a premium, intercropping is a good plan!
Fast growing crops are good for intercropping in the vegetable garden.
Vegetable plants can be grown quite closely together in most cases. Together with this, many vegetable are quick growing. An increase yield of between 30-40% can be obtained with a little thought.
It makes sense for plot utilisation, to plant some of the faster growing vegetables between the row of the slower maturing types. Or, even between the individual plants. This is known as intercropping and is practiced on most successful vegetable gardens.
Another reason - other than space - is the fact that the Legume group of vegetable plants - Peas and Beans of all types - release nitrogen into the soil. Nitrogen is necessary for leaf growth, so it is a good idea to plant quick growing lettuce and other leaf crops near to or in between Bean and Pea crops.
Fast growing vegetables for intercropping between slower crops .....
Lettuce - especially the smaller tom thumb, and Little Gem
Radishes - grow them alongside or between other 'root ' crops
Slower growing vegetables that will have a bit of space to spare in the early stages....
Swede & Turnip
Sweet corn is a good home for most quick-growing vegetables - also some dwarf French beans can grow between the maturing Corn stalks.