Few weeds can fight potatoes!

Ever wondered why we usually grow many veg in rows? Two main reasons: to make it easier to cultivate and weed between the plants, and so we know where they are!

What is the best spacing and arrangement for various crops? It depends how you grow them and what you want to achieve.

First you need to bear in mind my previous post: they must have sufficient light, water and nutrients. The more you want to produce from a given space the more effort you have to make to ensure none of these are deficient.

Water and nutrients you can maximise if you put in a bit of extra effort - relatively easy if you are cultivating a small plot. Attention to the soil is essential if you want to intensively crop. Incorporating plenty of compost or other organic material improves the structure, water retention and nutrients of the soil, this can make quite a difference to the crop you can squeeze out from a given area.

Double digging - going down 1.5 to 2 spade depth to break up the soil and incorporate organic material can make a big difference for crops like pole beans and some root crops like carrots and parsnips. This is hard work so best done selectively but once you have done that and eradicated any perennial weeds you can opt to use ‘no dig’ methods provided you keep off the soil when it’s wet (ideally at all times) so you don’t compact it.

You will need to ensure there is sufficient water especially if you want to grow intensively. If you won’t be able to water in dry spells, especially when crops are first germinating and when they are getting ready to crop, then you are wiser growing less intensively.

Incorporating a little general purpose (balanced N, P, K) fertiliser like blood, fish & bone for organic growers or ‘growmore’ type for chemophiles helps ensure the major nutrients are present. Top dressing with nettle and / or comfrey ‘tea’, diluted urine (best stop application a month before harvesting, I’ll talk about using urine as fertiliser another day), or chemical fertilisers biased towards N and K (crop dependent) when plants are growing strongly can make a big difference to yields.

Light is mostly a question of competition: with weeds and with other crop plants growing close. The key is to weed and thin as early and as often as possible. If you give your crop plants their best possible start so they can grow unchecked they will soon become sufficiently established to make life difficult for any new weeds.

When plants first germinate and emerge it’s likely a fresh crop of weeds will be doing the same and it’s usually quite hard to tell them apart when young. Annual weeds are easiest dealt with using a hoe between the rows in dry weather - you need about 8″ (20cm) between the rows to safely do that.

Many veg are relatively insensitive to different between row and within row spacings. Ideally they would like the optimum distance in all directions but most barely mind if the ratio is up to 2:1, so plant your leeks or garlic 9″ x 8″ apart or 12″ x 6″ apart they get the same space and you will get about the same yield. If using small beds that you can reach over easily I would make the spacing as even as possible, offset the rows and perhaps even grow a little denser, maybe 8″ x 8″. If the rows are long and you need to walk through them then you’ll certainly need at least 12″ between some rows even if you have dainty feet.

How does density affect yield? Up to a point increasing the density of your crop plants will increase total yield. But as you increase density some of that yield becomes too small to be usable. Generally if you want a bigger vegetable you should give it more space but you will lose some total yield. If you want smaller vegetables then give them less space, you will get a larger total crop but a greater proportion will be too small to use.

Many crops can be grown surprisingly close together provided you look after them. But beware of growing crops that are prone to ‘bolt’ and ‘go to seed’ too densely - spinach and chinese cabbage sometimes catch me out - they can get upset and rush into flower. It’s as if the plants decide they’re going to have a hard life so had best seed themselves before it gets any worse.

When you transplant growing plants or sow individual large seeds like beans, tubers or bulbs you can set the spacing more precisely. When you sow small seed it’s almost impossible to get between plant spacing ideal and often you can’t be too sure what germination rate you’ll get, so you will almost certainly need to thin. Some crops like carrots you can thin in stages and use later thinnings to eat. Others like lettuce - if you carefully lift them - thinnings can be transplanted elsewhere.