One of our tastiest and most rewarding crops can be sweet corn, easy in the southern counties but a tad harder further north. This is not maize but a very distinctly improved sub variety, and far superior in edibility to animal fodder or starch and oil producing maizes farmers grow, or the mealie types from developing countries. In fact Sweet corn is almost solely an Anglo-American result of relatively recent breeding. Surprisingly the French have mostly missed this treat- perhaps from chauvinistic self denial, though to be fair so have most other Europeans, indeed most other countries entirely. Although maize crops are hugely important almost everywhere and most snack foods contain starch or oil derived from the ripened kernels of other varieties the pleasure of a cob of quickly cooked sweet corn, dripping with butter, is just not generally known world-wide.
The original maize was South American and so long in cultivation there are no known wild precursors. The southern and central native Americans developed many strains and their farm economy was heavily reliant on this productive and easily storable crop. It was often grown combined with beans and squashes, the Three Sisters as they were known and a trio of companionable plants that still work well today, as mentioned further below.
One huge advantage of maize over wheat, rice and other cereals is the return per plant. One seed begets hundreds, a huge multiple. A direct result is the plants need much more space apiece. So sowing effort is also much reduced and instead of having to level and prepare large areas of tilth the ground can be left much rougher with station sowing at a patchwork of improved spots. Likewise harvesting was simple and rapid and threshing not required. There was thus much less need to develop mechanical aids such as plough, harrow, seed drill etc.
And this huge return per plant has resulted in a major reason for failed crops. I cannot believe the number of allegedly knowledgeable garden presenters I have observed over the years who obviously could never ever have succeeded with this plant. I am staggered over and over again by their sowing and planting densities. Even if you had soil made from nearly neat fish manure with continuous drip feed watering you could never get decent, if any crops at all, from the sort of spacing I’ve watched them demonstrate. At those spacings even wheat would be crowded let alone sweet corn.
Sweet corn plants need, must have, at least, the same sort of spacing we give courgettes, main crop spuds and the larger brassicas. Crowding just causes congested poor plants and miserable crops -which are usually blamed on the weather. In poorer or drier soils a couple of feet each way is necessary, in better conditions possibly half that but never less. You can likewise cramp sweet corn in containers- in small buckets they will just do, in big buckets one for each plant, they do much much better.
Obviously the richer your soil or compost and the moister, the more you feed and water, then the closer you can plant. But there is still the problem of limited sunlight- too crowded also means only the outer plants in a block get enough. Wider spacing ensures all get some light and thus better crops. (You know of course that we grow sweet corn in blocks not rows hoping to ensure better pollination - which can be aided by hand).
Given sufficient spacing and preferably rich moist soil, then squashes can ramble underneath enjoying the shelter and dappled shade as can dwarf beans. Climbing beans can run up the sweet corn but are rather competitive in our low light conditions- and occasionally pull the plants over. (All these companions are better sown and planted separately and later, but can be successful raised in the same pots as the later sweet corn batches.)
Closely related to timing is the amount of sun when the cobs are swelling- late crops up till the frosts are theoretically possible but earlier ones are sweeter, fuller and bigger by far. This means earlier sowing and planting are essential to get your cobs ripening, preferably before the end of August! (You can raise crops under cover to mature long before, these can be even sweeter though slightly trickier as the male flowers open too long before the females thus pollen needs saving and applying by hand.)
Those plants sown in situ, all other things being similar, are usually bigger and better cropping than those transplanted. However those sown in situ are also often entirely absent. Sowing in pots, under cover, and especially with warmth, is much more reliable. The best policy is to do both, with extra seeds at each station when sowing in situ, it may not be cheap but it’s worth doubling or tripling up seeds with later thinning.
The hillock method requires even wider spacing, a metre plus each way, between enriched hillocks with three plants on each- so sowing five or six and thinning. Sowing on a raised hillock is also slightly warmer, as can be ridges, and either are especially useful methods in colder wetter soils. It is cold wet roots that kill sweet corn which is nearly hardy if drier. Cold winds are detrimental and worth defeating with plastic bottle tubes when either sowing or after transplanting. (These can be left in place for the plant to grow through and then aid watering, feeding and earthing up basal roots.)
In drier soils small pits can also be useful for individuals or groups both sheltering them from the wind and conducting water towards the plants.
We tend to sow too late and whenever you have been sowing with success I suggest you hazard even earlier batches a fortnight or even more before. Especially if hillocks, ridges, tubes, pits or cloches are now employed. And of course even earlier sowings can be started indoors, hardened off and be planted out before the outdoor sown ones have yet emerged. I am sowing batches indoors from the end of March and outdoors from the end of April.
When planting out, even more than when sowing, it’s worthwhile enriching each site, especially with phosphate and nitrogen rich materials. Dead bodies, particularly fishy ones, are ideal, though may encourage vermin. Fish, blood and bone meal or powdered poultry manure are less problematical. However although each will increase yields, in drier areas giving sufficient water later is more crucial. (And peeing in the water works wonders.)
In very windy gardens it’s worth employing small pits not only to keep the plants more sheltered but to aid earthing up. Sweet corn once tall usually throws extra roots from the base of the stem which help stabilise the plant. Earthing up aids this and obviously is more effective where the plants were set in shallow pits.
Now well spaced plants in good moist soil should ripen at least two cobs apiece. You can get further cobs but these usually miss full pollination and are usually scantily filled. With careful pollination three are possible from the earlier batches but the later plants can seldom ripen three, in fact any more should be removed to prevent these runts robbing the other two.
Pollination is aided by running your hands over male tassels emerging from the tops of the plants then over female silks coming out the ends of the cobs. Now we are fed mal-information on pollination that is not exactly wrong but totally inappropriate. We are told that if we grow different varieties near each other they’ll cross-pollinate and not give good crops. This is rubbish, it may be true for the farmer able to sell only perfect cobs tosupermarkets but to the home gardener the odd kernel of a different hue or size is pretty irrelevant. I have, repeatedly, sown blocks of up to a dozen and a half intermingled varieties (each variety in triples). Most plants cropped normally and very few cobs were badly affected in any major way, only an odd looking kernel here or there. (One obvious reason is the flowering windows of each variety seldom coincide so cross pollination is much less frequent than feared.) Thus although I do not recommend such extreme mixing there is little danger of serious problems with growing several varieties especially with quicker and slower maturing sorts.
Indeed with a block of several varieties the major problem is how do you tell when any cob is ready? By peeling back the husk you can see if the kernels are regularly well swollen. Then press a typical kernel with your nail till it bursts. Runny and watery is not ready, thick and lumpy is too late, creamy is perfect. Over-ripe kernels wrinkle and are too tough to eat as sweet corn though they can be dried and used for grinding or animal and bird food.
Do not pick cobs till just before eating time- get the pan of water boiling, go pick and shuck the cobs and plunge them in straightaway, and boil no longer than twenty minutes! Any delay after picking and they will be less tender and sweet. The latest improvements in breeding are not to get modern varieties to crop sooner but not to go over so fast. Even so they rarely stay at their peak for long though some bred for the supermarkets can be picked to remain edible several days longer. However freshest is best.
Pop-corn is similar, slower to mature, it must be ripened fully so needs a really warm summer to enable the kernels to later ‘pop’ when heated. (Beautiful plants though with carmine silks.) If by chance you get a plant that matures without a cob then peel and chew a chunk of stem -the sap is quite sweet rivalling sugar cane. And one last tip- bundles of dried stems and leaves make excellent wild life hotels which seem especially appealing to ladybirds.