Sweet Corn
Home-grown sweet corn is a must for the garden, if you have the space (and enjoy corn!). For maximum sweetness and flavour, sweet corn must be consumed as soon as absolutely possible from the time of picking. This is because the sugars within the corn kernels begin to transform into starches, which reduces the cobs sweetness. This means, that the corn you buy from the shop will never be as sweet and tasty as the corn you grow yourself!
Today I harvested my first four sweet corn cobs, and I have another 6-7 almost ready to be picked on my plants.
Growing Sweet Corn
Sweet corn is a fairly easy vegetable to grow. It is a hungry crop in that it takes a fair bit of nutrients from the soil during its growing process, especially nitrogen. Because of this, it is not a good idea to plant corn in the same area as a previous corn or other nitrogen hungry crops. Instead, try planting in a bed that has had legumes such as peas or beans growing, as these plants fix nitrogen into the soil through symbiotic relationships with soil bacteria.
Fresh packet corn seed germinates very readily. The seeds should be planted directly into the bed where the plants are to go. For corn, it is best to plant in blocks, as the plants need to be pollinated by wind, and close contact will help this. Plant each seed a minimum distance of 30cm apart. In warm soil, you can expect germination within about 10 days.
Corn is a warm season crop, and will start to die when average temperatures drop below about 16oC. In Canberra this occurs by about the end of April and into May. If, possible corn prefers a warmer temperature than this, around 25oC.
From sowing to harvest, sweet corn will need between 10-12 weeks before cobs are ready to harvest. The plants from the photo above were planted in the first week of January, and were harvested on the first of April. In Canberra, January plantings of corn may fail if early Autumn temperatures arrive, and would preferably be planted earlier, after the last frost in November or December. To prolong the corn harvest period, plantings should be staggered.
Fertilising Sweet Corn
Each sweet corn plant produces both male and female flowers. Male flowers are produced on the top of the corn stalk. They can also be identified by finger-like straight flower. Male flowers produce copious amounts of pollen, which is blown by wind onto the female flowers;
Male sweet corn flower
Female flowers look like strands of fine golden silk, and are generally located toward the middle or bottom of the plant. Corn plants will generally produce between 1 and 3 female flowers per plant, and each of these female flowers can develop into a corn cob. If all the strands are fertilised successfully then all the kernels in the cob should develop, and corn cobs with missing kernels mean that not all the silk strands were pollinated successfully.
To aid with pollination it can help to give each of the corn stalks a shake whilst the female flowers are still young and still golden. If you wait until the strands have turned brown then it is too late. Typically this lasts for about 2-3 weeks.
Female sweet corn flower with new, golden strands and old, brown strands. This cob will be ready for harvest soon.
Harvesting
Sweet corn needs to be picked as soon as it is ready to ensure maximum sweetness. This can be recognised in two main ways. Firstly the silk tassels on the female flower will all die down into a brown colour and no, or very little golden strands will remain. The second test you can do involves peeling back a small piece of the husk until the kernels are visible, and then pierce one with your fingernail. If the liquid that comes from the kernel is clear, the corn is not quite ripe, but if it is cloudy then the corn is ready to pick.
When picking the corn, grab the cob and pull downwards twisting at the same time and the cob should come right off easily, without damaging the plant.
