Corn is one of the oldest edible plants and traditionally it is grown in garden beds and fields however, not owning either, I have had great success in growing crops of corn each Summer in containers on my Balcony. This means that you too can grow in your small space!
Just a word of caution…whilst growing corn in my experience is not difficult, if you are a nascent grower, it would be better to start off with less ambitious plants that provide continuing fruit or yields through a season such as leafy greens, beans, tomatoes, capsicums etc.
Corn provides a limited yield that takes a long season to come to fruition. Typically you want to use largish containers to reproduce optimum external conditions as close as possible but of course, on a Balcony or small space you've got to be conservative and select containers that won't compromise your Balcony weight and still allow other plants to grow nearby as well.
Corn is typically wind pollinated so bunching them up assists to ensure pollination, however, I will explain a very good hand pollination technique that works in small spaces. I have 3 or 4 pots of corn growing at any time.
I look for varieties that are sweet or decorative/colour and is a dwarf variety which will grow easier in a small spaces.
I like to look for early varieties, and shorter varieties which are sweet and short. I raise the plants from seed however, your garden centre will have a great selection of seedlings available.
Most seed companies offer dwarf varieties for container growing. Select a variety that yields more than one ear per plant. This also helps with self pollination. A larger grouping ensures complete pollination. A few to consider are Golden Bantam, Jolly Roger.
Corn roots typically have an effective depth of 30 centimetres, although in the field some roots can reach much deeper. So in container gardens corn doesn't need a particularly large pot - a 30cm container for about 2 or 3 plants should be sufficient but if you can go larger that’s great. In our range of Root Pouch grow bags we have sizes from small to huge portable garden beds to grow your small space field of corn! Fabric bags are a great solution to the problem of how to store containers after cropping and makes moving your corn around to follow the sun or protect from extreme weather easy and portable.
A key consideration is the resulting height of the corn plants. It's a great accent piece and very architectural! Yet think about container placement as well as wind protection! They are fabulous for casting shade on to shorter plants.
For corn, use standard potting soil and make sure to add lots of slow release fertiliser such as a potting mix with Dynamic Lifter. If you are using old potting mix (I never throw out potting mix, always refreshing it with Balcony made amendments.)
Check out the Make Potting Mix at Home Recipe card written by Angus Stewart, an expert in the field. Ensure you add loads of organic matter such as compost and aged manures.
Corn needs full sun, no exceptions, and must have protection from strong winds. Ensure your corn plants have a regular supply of food and water. They are heavy feeders and thirsty. Never let it completely dry out. Provide fertiliser once a week or bi-weekly using a liquid fertiliser.
When the plants tassel, help them pollinate by gently shaking the stalks or hand pollinate if you have multiple varieties. You can see this technique on my Instagram.
The hardest thing with sweet corn is how to tell when it is ready to pick. Some indicators are roughly at the 2 to 3 week mark after flowering, when the tassel turns dark brown/black, feeling firmly along the cob to feel the size of the corn kernels, puII back part of the sheath and pierce a couple of grains using your fingernail, if a water liquid squirts out the cob is unripe, if the liquid is creamy then it is ready to pick.
Handy tip: pile up compost around the base of the stem. Called “hilling”, making mounds of compost about 15 – 20cm high will increase the amount and flavour of your sweet corn! This also helps to stabilise the roots. Some corn stalks get a little bendy in the winds if you are in a high-rise block so tying them to a few long Tomato stakes will help to keep them upright.
Sweet corn cobs freshly picked from the garden are far tastier than those from shops. The reason for this is that the sugar in sweet corn quickly turns to starch giving a very dull flavour after only a day or so.