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vegetable growing techniques
Corn
raised bed corn growing method
The trouble with standard planting distances for corn is that they generally do not fit the dimensions of a typical raised bed, (around one metre wide).  Below is a step by step explanation of how to raise good sized corn within the confines of a raised bed.


1. prepare the bed
Add a shovel full of cow or sheep manure per metre length of bed.  Some blood and bone, compost and rock dust can also be added.  Mix in with a hoe and rake level.  I sometimes  also cover with a thin layer of mulch.

2. dig depressions

Illustration of corn planting spacings.  Each arrowed line represents a distance of about thirty centimetres (12").
Dig a series of shallow bowl shaped depressions about three centimetres (1 1/4")deep and twelve centimetres (5") in diameter in a three, two, three pattern down the raised bed.  When three depressions are dug the two edge holes should be pretty close to the sides.  I always start and end with a three depression pattern.

A general rule of thumb is that the centre of any one depression should be around thirty centimetres from any of it's neighbouring depressions.  If you have covered the bed with mulch then push the mulch aside when digging the depressions, leaving them bare.

3. plant seeds
Plant three or four seeds in each depression and cover with two centimetres (3/4") of friable soil but don't fill the dreprsssions all the way to the top, still leave a dip of around one centimetre (1/3").  Corn seeds should only be planted after the threat of the last Spring frost has passed.

Lightly water each depression.  These depressions naturally funnel the water to the seeds and allow you to easily identify where the seeds have been planted.  When starting out I only water the depressions.  Note that I use these depressions because I live in a fairly dry area.  If you are in a high rainfall area that is likely to result in waterlogged soil than do not dig depressions but plant your seed into flat ground.

If birds are likely to dig up the seeds then protect with wire mesh or small stakes driven into the ground.  For more details see the Deter - Birds webpage.

Protect against slugs and snails if they are a problem in your garden.  See the Pest Control section for more information on protecting vegetables from slugs and snails.


Photo of four young corn seedlings
Four young corn seedlings in a single depression.  These will be thinned down to just one mature plant.

Photo of mid sized corn plants
Mid sized corn plants in the three, two, three planting pattern.  After the corn had been thinned out extra mulch was added.
3. Thin seedlings
As the seedlings grow thin out to just one seedling in each depression.  I usually do that when the seedlings are between three and ten centimetres tall. 

Leave any removed seedlings right next to the remaining ones as they will act as a decoy for slugs and snails.

Pick the most vigorous seedling to keep and not the most central.

If all the seeds fail in a single depression then carefully transplant a  spare  seedling from a neighbouring depression.  Do not replant failed depressions with more seeds. This is because all the corn needs to mature at the same time if they are to be properly pollinated.

If enough seedlings do not survive then pull out all the remaining seedlings and start again.


4. growing stage
By the time the plants are twelve centimetres (4 1/2") high you should be down to one plant in each depression.

Heavily mulch around the plants and water fairly regularly, especially in hot weather.  As the ears of the corn begin to swell out give the plants extra water.


Concluding comments
I have used this method of growing corn in a raised bed for over twenty years now and it has produced excellent results.

By planting extra seeds and thinning out I get the right amount of mature corn plants where I want them.  And by spacing them in a three, two three pattern thirty centimetres apart they are in a tight enough block to ensure proper wind pollination but far enough apart to get corn plants that aren't stunted because of lack of space. 

I usually grow thirteen corn plants each year from which I get around thirty five to forty good sized corn cobs

For space reasons I only plant one crop each season though you can stagger a number of corn plantings over a season.  However I think you need a minimum of eight plants in each planting to ensure proper pollination.