The basic rule with small scale city gardening is to pick little and often. Most vegetables will benefit from having almost mature fruit removed so to encourage new fruit. In this respect a kitchen garden should be visited for produce just as often as visiting the kitchen.
Tomatoes particularly benefit from regular picking. While it is nice to have plants covered in ripe tomatoes, in reality the fruits are ready once fully formed and green and will finish ripening off the vine. The main consideration with tomatoes is that the fruit is picked while firm and before it becomes soft.
Beans are the most obvious beneficiary of regular picking. If beans are left too long on the plant the mature beans will actually prevent the plant producing new beans. Picking the beans before the actual beans show through the skins provides tender young beans ideal for daily use.
Cucumbers do not continue to ripen once removed from the plant. That said, cucumbers left too long on the vine become yellow and bitter. With two or three plants in a garden cucumbers can be picked every other day over a long season providing a healthy fresh component to the diet.
The main benefit of all this regular picking is that the weekly household diet can become orientated towards fresh garden produce. Combined with salads, herbs, peppers and courgettes, about 50% of a family diet can be met from the garden during the few months of summer.