In today’s article, we talk about corn cultivation in the home garden, focusing on self-consumption, as it was originally intended for this important crop. Corn is a plant with ancient origins, still undergoing genetic evolution and not easily categorized. It has been used for human consumption since ancient times. In the past century, it was extensively grown in vegetable gardens in rural areas for self-consumption. With the resurgence of sustainable agriculture in recent years, many native varieties have been rediscovered, which can now regain value through seed exchange among the latest generation of farmers.
Let’s delve into the history of corn, its botanical classification, and the various possible variety choices. Finally, we’ll explore its integration into crop rotations in the home garden using organic cultivation techniques.
Corn: Origin and Spread
Corn is native to South America, specifically originating in a region between Honduras and Mexico. Although its exact ancestors have not been identified, it is known that corn existed as early as 6000 BC, as evidenced by archaeological findings in Tehuacan, Mexico.
Corn cultivation was introduced to Europe after Christopher Columbus’s second voyage in 1493. Later, it spread to Africa through Portuguese influence and, by the late 1500s, to the East, reaching China.
In Italy, corn cultivation began to spread in the early 1600s, likely with varieties from the Balkans. Due to these origins, it gained the popular name “granturco.” Historically, corn was primarily grown in the northern regions of our country. However, the central and southern regions also used it as a valuable contribution to the precarious food supply of rural populations, leading to its incorporation into regular crop rotations.
In the last century, our corn cultivation has undergone significant changes, shifting production towards large extensions for the market, transformation, and distribution. Corn slowly disappeared from marginal areas, concentrating almost exclusively in large irrigated plains. Here, thanks to the introduction of hybrid varieties, it ensured high yields and profits, but at the expense of biodiversity and food diversification. With this article, we aim to reintroduce corn into home gardens. But first, let’s start with a description of the plant.
Botanical Characteristics of Corn
Corn is a herbaceous crop belonging to the botanical family Graminaceae, subfamily Andropogonoideae, and tribe Maydeae. The species we are discussing is known by the scientific name Zea mays, a species characterized by high polymorphism that we will explore shortly.
Corn’s roots are of the fasciculate type, mainly spreading near the surface. Under optimal cultivation conditions, they can reach significant depths. There are three types of roots: seminal, adventitious, and aerial. Seminal roots originate from the seed and quickly exhaust their function; adventitious roots form the main root system; aerial roots are above the ground and serve a mechanical function.
The corn stem, also called culm or stalk, varies in height from 50 cm to over 5 meters, with an average of 2-3 meters for the most common varieties on our continent. It consists of a series of nodes and internodes, with the number varying from 12 to 24, depending on the variety.
The leaves are arranged alternately and consist of a sheath that wraps around almost the entire length of each internode, serving to protect the vegetative apex. The leaf blade is lanceolate and smooth. It is intensely green on the upper surface and lighter on the lower part. The leaf development varies both among varieties and within the same plant, reaching maximum size in the median leaves.
Corn is a monoecious diclinous plant, meaning it has both male and female flowers but carried on different inflorescences.
The male inflorescence, called tassel, is a terminal panicle with several branches where the flowers are located. These flowers are grouped in paired spikelets, one sessile and the other pedunculate.
The female inflorescence, known as the ear or cob, is an axillary spike, usually found at the sixth or seventh node below the male inflorescence.
The classic corn cob is carried on a peduncle formed by closely spaced internodes and nodes. Bracts emerge from the nodes of the peduncle and completely cover the ear, forming a protective husk.
The cob consists of the cob axis, on which the kernels are inserted, called cariopsis, which are the straight and regular spikes of corn seeds.
The corn seeds, as mentioned, are called cariopsis, which are indehiscent fruits formed by the embryo, endosperm, and involucres.
The cariopsis consists of the crown, which is the part facing outwards in the cob. Then there are two faces, the upper one facing towards the apex of the cob, and the lower one towards the base. Finally, there is the shield, with the embryo, located at the base of the grain on the upper face.
Corn seeds exhibit high polymorphism, meaning there are marked differences between different varieties. These differences primarily concern color, shape, and weight. For example, the color can range from yellow to white, violet, or red. The shape can be round, flattened, pointed, etc. The number of seeds contained in a single cob also varies greatly, ranging from a minimum of 400 to a maximum of one thousand grains per cob.
Different Corn Species
Due to the high polymorphism of the cariopsis, several subspecies of the Zea mays genus we are considering have been identified. Let’s see which ones they are.
- Zea mays sup-sp. everta or popcorn, to which the most primitive types belong. The cariopsis is cup-shaped, very small, and high in protein content.
- Zea mays sup-sp. indurata or flint corn, with a roundish cariopsis. Many old European varieties belong to this subspecies.
- Zea mays sup-sp. indentata or dent corn, a species named after the typical indentation present in the crown. This is caused by a decrease in volume due to moisture loss during maturation. The color in this species ranges from white to yellow to red, while the shape can be elongated, pointed, or flat. It is the predominant subspecies on which hybrids are developed.
- Zea mays sup-sp. amylacea or soft corn, a species used for starch extraction.
- Zea mays sup-sp. ceratina or waxy corn, including the original forms from China. It is used in the food industry as a substitute for cassava flour, as a dietary food, and in the textile and paper industries.
These are the main subspecies, and within them, there are hundreds of varieties.
Due to its adaptability and genetic variability, corn is the plant most subjected to genetic improvement and hybridization among cultivated crops. This genetic evolution has led to the creation of numerous hybrid varieties, aimed at improving productivity and resistance to climatic and environmental adversities (parasites and diseases). However, this genetic improvement has come at the expense of biodiversity, resulting in the loss of many local varieties that were traditionally grown for self-consumption.
Fortunately, in recent years, corn cultivation has been making a comeback in rural areas, marginal zones, and home gardens. This resurgence is thanks to traditional seed exchange fairs, which allow the rediscovery of the biodiversity preserved in our countryside. Thanks to these activities, many native corn varieties have been recovered and exchanged, and we want to list some of them:
- Pop-corn from Pollino
- Everta blue, Pollino
- White pearl, Vigianello (PZ)
- Sponcio, Tortora (CS)
- Indiana paesana, Decollatura (CZ)
As you can see, in a limited area, many ancient species have been rediscovered, and many others are waiting to be unearthed. This is a task that every conscious farmer should undertake!
Now, let’s explore corn cultivation in the home garden, starting with its biological cycle, which takes place between spring and autumn. In this timeframe, we can distinguish four fundamental phases: germination, vegetative development (or levata), flowering and pollination, filling, and maturation.
The temperature and light greatly influence corn cultivation. This plant produces less if the temperature exceeds certain limits. The optimal daytime temperature for development ranges between 24 and 30 °C. The nighttime temperature should not drop below 15 °C. Corn is usually not cultivated in areas where the average summer daytime temperature is below 19 °C. However, it can be grown in mountainous regions, but preferably in better-exposed and sunlit areas.
Regarding light, corn is a typical heliophilous plant, meaning it responds optimally to high light intensity, which is generated at temperatures above 30 °C. Consequently, low temperatures during the summer period slow down its vegetative development.
Sowing Time and Spacing
Corn is sown in spring when temperatures are stably above 12 °C. Below this threshold, the seeds cannot germinate, and late frosts may kill young seedlings. The seeds are directly sown into the soil, burying them about 1 cm deep. The spacing between plants is 20-25 cm, and the distance between rows is 70-80 cm.
Soil and Fertilization
The best soil for corn cultivation is one that has been worked to a certain depth. Its consistency should vary from loose to medium loamy, tending towards clayey. Additionally, it should be rich in organic matter and have high water retention capacity, while avoiding excessive waterlogging.
These are the ideal conditions, but corn can still produce good yields in other types of soil as long as they are not too cold or excessively wet.
For fertilization, given the plant’s high nitrogen demand, an abundant application of organic manure in the winter period would be advisable. Alternatively, corn can be grown after a green manure crop of legumes.
If summer rains are frequent and regular, corn cultivation does not require additional irrigation. However, in recent years, there has been a decrease in precipitation from spring to summer, from north to south. Therefore, during the hottest periods, it may be necessary to supplement with artificial irrigation. For this reason, installing a hose-based irrigation system or furrow irrigation can be beneficial.
In small corn cultivations in home gardens, which were widespread in the past in our country, companion planting with other crops is common. This is facilitated by corn’s rustic characteristics and its vertical growth. Together with sunflowers, corn is one of the crops that can add verticality to the garden without the need for supports.
Plants that are usually companion planted with corn include legumes such as beans, peanuts, soybeans, or long-cycle vegetable plants like squash.
The main cultural operation to be carried out on corn is weeding, that is, removing weeds. Unfortunately, in large-scale cultivation, this is done using chemical products such as glyphosate, which are highly harmful to humans and the environment.
In home gardens, we can safely proceed with manual weeding or use natural mulching with straw. This greatly reduces the laborious manual work and also allows for significant water savings.
Harvest and Uses
Corn is usually harvested in September when the ears are mature and begin to open. In industrial-scale cultivation, this process is done using large combines equipped with a special sheller head to harvest and clean the cobs. In large plots, corn is cultivated for both human consumption (production of dry and fresh kernels) and animal feed (wet or dry kernels, waxy corn, kernel-cob mixtures). The production of corn seed oil, cornstarch extraction, and cornmeal are also prevalent.
In home gardens, the harvest of corn is straightforward. It can be done manually, cob by cob. The cobs are detached from the plant, husked to remove the bracts covering them, and then left to dry before being shelled. Of course, this process is suitable when using dry kernels. In the case of consuming fresh cobs, naturally, there is no need for drying.
Fresh cobs have various culinary uses. The classic ones are the simplest, reminding us of the past when corn cobs were boiled or roasted and enjoyed as a snack.
Here you can find the nutritional aspects of the plant.
Biological Pest Control
In intensive corn cultivation, especially in highly exploited soils, there is a risk of several pest attacks.
In home gardens, with a better ecosystem balance and less intensive agricultural practices, these risks are significantly reduced. Nevertheless, for completeness of information, we will mention the main corn pests.
These pests can be divided into hypogeal (subterranean) and epigeal insects. The subterranean insects attack the underground parts, while the epigeal ones attack the vegetation.
Among the hypogeal pests, we can mention:
- Agrotids (genus Scotia) in their larval stages, which come out of the ground during the night and nibble on the plant’s collar.
- Elaterids (genus Agriotes), also in their larval stage, which attack the germinating seeds. They can also cause damage to the roots and collar of the plants.
- Specific species of root aphids that form colonies of green color in the root system. This causes a significant delay in vegetative development, in addition to leaf yellowing.
- Mole crickets (Gryllotalpa gryllotalpa), very active in humid soils rich in humus. They cause damage by nibbling on germinating seeds and cutting adventitious roots.
- White grubs (Melolontha melolontha) larvae also perform trophic activity on the root system.
Among the epigeal insects, i.e., those that attack the above-ground part of the plant, the main enemies of corn cultivation are:
- European corn borer (Pyrausta or Ostrinia nubilalis)
- Mediterranean stalk borer (Sesamia cretica)
The damage caused by these two insect species is very similar, often difficult to distinguish, and their effects can be cumulative. They primarily damage the leaves and, more severely, the ears.
For biological control against these pests, which, as mentioned, primarily act in their larval stages, the most effective product used in organic agriculture is Bacillus thuringiensis var. kurstaki, which we have discussed in detail before and is available here.
- Department of Agronomy, Iowa State University – “Corn management following cereal rye cover crop with strip tillage and starter N fertilization (2018-2020)” – This research evaluates the effects of a winter rye cover crop-free zone through the use of strip-tillage and starter fertilizer to improve seedling vigor and eliminate yield drag associated with winter cereal rye.
- WebMD – “Health Benefits of Corn” – Corn, also known as maize, is a starchy vegetable that comes as kernels on a cob. It’s one of the most popular vegetables in the U.S. and has various types, including sweet corn, popcorn, flint or Indian corn, and dent corn.
- Healthline – “Corn 101: Nutrition Facts and Health Benefits” – Corn, also known as maize, is a popular cereal grain rich in fiber, vitamins, minerals, and antioxidants. It may promote eye and digestive health. Whole-grain corn is healthy, but refined corn products offer fewer benefits. Corn comes in various colors and is used in many products like tortillas, cornmeal, corn syrup, and corn oil.