Many people are familiar with the golden-yellow fruit growing in the fields, but did you know you can easily grow sweet corn yourself? Find out all there is to know about planting corn.
Corn (Zea mays), also known as maize, belongs to the grasses family (Poaceae) and originated in Central America. Today, our fields are predominantly cultivated with corn varieties which, due to their high starch content, are used as fodder crops or as a renewable raw material for the production of biogas, bio-fuel or biomaterials. Maize is one of the most important staple foods in the world and is consumed in many different forms.
The best corn types and varieties for consumption
There is a wide range of corn varieties and types. They can be classified according to their grain type, which in turn has different uses. Flint corn is made into cornflour (also known as corn starch) for cooking and baking, dent corn is used milled to make doughs and bread, and flour corn is used for making tortillas. There is also the delicious and ever-beloved popcorn as well as sweet corn that can be enjoyed barbecued on the cob for instance. What makes sweet corn special is that the sugar stored within the kernels is only slowly converted into starch during ripening. This explains the pleasantly sweet taste of the corn kernels.
Corn varieties for growing at home
The heirloom sweet corn variety ’Golden Bantam’, known since 1902, has delicious sweet and tender cobs. As it thrives in cold soil, this variety is ideal for planting early in the year. Compared to other sweet corn varieties, it has a long harvest window from early August to mid-October. As the sugar converts into starch quickly after harvesting, it is best to eat the corn cobs as soon as possible.
The sweet corn variety ‘Ashworth’ ripens very early, about two weeks earlier than ‘Golden Bantam’ in fact, making it particularly suitable for cooler regions of the UK. It grows up to 150 centimetres tall.
The variety ‘Mezdi’ is very sweet and flavoursome and grows up to 180 centimetres tall. Harvest from September to October. Unlike ‘Golden Bantam’, the sugar here is only slowly converted into starch.
Small sweet corn varieties for the balcony
Due to its medium growth height, the early-maturing sweet corn variety ‘Damaun’ is great for growing on your balcony. The corn cobs are somewhat smaller than those of the later maturing varieties.
The very early variety ‘Yukon Chief’ is a very good choice for those of us with limited space as it only reaches about 40 centimetres tall and has a ripening time of just 55 days. It bears golden-yellow, sweet corn cobs that are about 10 to 15 centimetres large.
If you are looking for something a bit more peculiar, the varieties ‘Jade Blue’ with deep blue cobs and ‘Luther Hill’ with white cobs have exceptional flavour as well as interesting colours. They are also dwarf corn plants, making them excellent varieties to grow in containers on the balcony.
In warmer regions, the corn kernels can be sown directly in the prepared bed or in the pot on the balcony. However, the optimum sowing time is important here. If the seeds are sown too early, there is a risk that the seedlings’ development will be impaired by too low temperatures. So, especially in cooler areas, it is better to plant corn plants in a sheltered place.
When to plant sweet corn?
Sweet corn needs sufficient warmth, so only sow or plant them out once the days and nights are frost-free. When sowing directly into the garden, sow the corn kernels as early as the end of April and protect them from the cold with a cover. Without a cover, sowing takes place in early to mid-May. If starting the seeds inside, sow them in mid-April and plant out the seedlings in the garden or in a pot two to three weeks later. Only early and medium-early maturing varieties are suitable for cultivating in the UK, as the growing period is simply too short for other varieties.
Tip: Sow the corn kernels indoors in a seed tray and plant out after the last frost. Starting sweet corn indoors has a considerable advantage over direct sowing as the sweet corn has more time to establish itself and the corn cobs are therefore more likely to be ripe.
Growing corn: where and how
Choose a sunny spot for sweet corn in your vegetable patch or on your balcony. Sweet corn loves heat and requires temperatures of 24 to 29 °C as well as plenty of sun to develop well. Sweet corn is a heavy feeder and has high demands when it comes to the nutrient content of the soil. The soil needs to be deep, moist and rich in nutrients and humus. Our peat-free Plantura Organic All Purpose Compost is ideal for planting corn in pots on the balcony.
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Starting corn plants indoors:
- When: mid-April
- Fill seed trays about 10 cm deep with soil
- Place the corn kernels with the tip pointing downwards 2 – 3 cm deep in the soil, spacing them about 5 cm apart, and cover with soil
- Keep soil moist
Planting out sweet corn:
- Carefully remove the corn seedlings from the seed trays
- Place in the soil keeping a planting distance of 45 cm
- Press the plants down well and water
Tip: By placing the root ball a little deeper in the soil than in the seed pot, the corn plant can develop more lateral supporting roots.
Sowing sweet corn:
- When: End of April to end of May
- Spacing: 45 cm
- Sowing depth: 3 cm
- Cover kernels with soil and press down lightly
Tip: Depending on the temperature, cover the kernels outdoors with a plant fleece for the first few days.
As sweet corn plants are pollinated by the wind, planting corn in groups is better than planting in rows. This arrangement ensures cross-pollination. To avoid pollination by low-sugar agricultural maize varieties, it is also advisable to maintain a distance of about 500 metres from the nearest maize field.
Summary: How to plant sweet corn
- Sow sweet corn: end of April to end of May
- Planting out sweet corn: Start sweet corn seedlings in mid-April and plant them out in the bed or pot 2 to 3 weeks later
- Sunny location; nutrient-rich, humus-rich and deep soil
- Planting distance: 45 cm, sowing depth: 3 cm
- Plant in groups to ensure cross-pollination
Tip: Corn enjoys being grown with sweet corn companion plants like winter squash and beans in what is known as a Three Sisters bed.
Corn plant care
Especially in the beginning, it is important to regularly remove weeds to ensure optimal plant development. Plant low-growing plants beneath your corn plants or add a layer of mulch to prevent weeds from multiplying too much and competing with the corn plants for nutrients and light. Water regularly and apply fertiliser occasionally to make the most of its yield potential.
How to water corn
Water corn plants regularly but do so sparingly. Though corn is relatively drought tolerant, a prolonged lack of water will lead to reduced yields. Moisten the soil especially during dry periods but avoid waterlogging.
How to fertilise corn
Like all corn varieties, sweet corn is a heavy feeder. As they absorb a lot of nutrients, it is best to apply a slow-release fertiliser when planting corn, such as our Plantura All Purpose Plant Food. Alternatively, mix compost into the soil. Apply fertiliser again when the corn plants begin to flower.
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When is sweet corn ready to pick?
Depending on the variety, the harvest time for sweet corn is between the end of July and the end of September. Unlike popcorn and dent corn, sweet corn is not harvested only once it is fully ripe. On the contrary, the right time to harvest sweet corn is when it reaches the “milk stage”. You can recognise that they are ripe by the fact that the kernels have already reached their final size and their typical variety colour. To be certain, puncture a kernel with your fingernail. If it contains a milky liquid, then it is ripe for the picking. The leaves and corn cobs will still be green at this stage. Only the corn silks at the top of the cobs are dry and brown around the time the corn is ready to be picked. To harvest the corn, either cut the corn cobs off or grasp the cobs firmly and then twist and pull them off.