Spacing plants correctly gives them the best opportunity for growth, and understanding a little more about this will really help with getting good results from your veg patch.
Each plant needs a certain amount of room for their roots and leaves to maximise growth. Planting too close together can mean slower or stunted growth. As an example, in the image above we planted several lettuces in a single, small pot. They have grown considerably slower than those planted further apart in the raised bed (using the same compost).
The other thing that is important with plant spacing is leaving enough air to circulate in and around plants. This helps to prevent diseases from spreading, especially in damp, humid weather. This is particularly true of spore driven diseases, like blight and mildew, as well as things like chocolate spot on leaves and beans.
If you are restricted on space, you could get away with planting most things a little closer together, but we would always recommend that you stick to the planting advice if you can. The exceptions come when you are growing things like cut & come again lettuces (which is why we planted up our salad pot in the picture) – as long as you pick the baby leaves regularly and keep the plants small then you can get away with it. Likewise, if you enjoy eating baby leeks/beets etc, then you can plant these a little closer together harvesting every other leek/beet along the row whilst still small and leaving the others to grow to full size.
If in doubt, stick to the spacing in our growing guides for a healthier, stronger crop!