Mint

25.05.17

Renewed interest among consumers for healthier lifestyles has seen an increasing demand for culinary herbs, like mint. In Australia, interest among home cooks in multicultural cuisines and the increased popularity of television cooking shows has also led to greater interest in fresh herbs.

Native to southern Europe and the Mediterranean, mint is used extensively in Middle Eastern, Indian, South American and Asian cuisines. The two most widely available types of mint are peppermint (Mentha piperita) and spearmint (Mentha spicata). They are both low-growing plants, which under good conditions, should grow to about one metre.

Overview

The leaves of both plants look similar with a smooth downy feel, jagged edge and elongated shape, however they taste quite different. Peppermint has a strong, cooling aftertaste due to the high concentration of menthol, while spearmint has a lighter and sweeter taste. Spearmint is the type most commonly grown as a culinary herb.

Culinary herbs as a commercial crop differ from many other market garden/vegetable crops. They are not generally consumed as a principal source of nutrition, but as a flavouring or condiment and are consumed in smaller quantities compared to vegetables. They tend to have a higher value per kilogram and so the value per acre tends to be higher. Commercial production still requires adequate soil quality and water supply in order to offer good returns from a small area of land. Depending on the cropping system used and the types and amounts of herbs grown, a successful culinary herb operation could operate on as little as two hectares.

Because the harvested product is generally packaged for retail consumption in small bunches or punnets, packing is labour intensive and quite expensive, while storage and transporting to markets is usually less expensive to undertake than for many other crops.

While herbs have some advantages in terms of returns for a relatively small investment in land and infrastructure, growing culinary herbs commercially is labour intensive as they are harvested by hand. Further, the high standards of freshness and quality that consumers demand means producers must commit a high degree of technical skill and effort to the enterprise.

Fresh culinary herbs are grown in every state of Australia by a diverse range of producers including specialist herb growers, market gardeners, horticulturalists and cottage/lifestyle growers. The majority of culinary herb enterprises are located on small land holdings on the urban fringes of Australia’s capital cities.

Herbs are also grown for non-culinary uses including for cosmetics, herbal medicines and essential oils.

The peak body for culinary herbs is the Australian Herb and Spice Industry Association Ltd. Protected Cropping Australia is the peak body for greenhouse and hydroponic horticultural producers.

Facts and figures

  • Mint is native to southern Europe and the Mediterranean and used extensively in Middle Eastern, Indian, South American and Asian cuisine
  • The two most common varieties of mint are peppermint and spearmint — with spearmint most commonly grown as a culinary herb in Australia
  • Demand for culinary herbs is growing as consumer preferences shift to fresh produce
  • Culinary herbs are considered to have several advantages as a commercial crop. They can be grown on less land than other crops and in areas with poor soil or limited water supply
  • A successful herb operation could operate on as little as two hectares of land
  • Herbs can be grown as broadacre crops, in greenhouses or hydroponically
  • Culinary herb operations are labour intensive

Production status

Fresh culinary herbs are grown in every state of Australia with the industry essentially comprising four main types of growers.

Specialist herb growers, specialise in growing culinary herbs. These producers tend to have properties between 5–40ha and employ up to 100 staff. These growers may also produce dry herbs or other value-added products. It is estimated that these growers account for 60–70% of all production, whether for manufacturing or the fresh market.

Market gardeners produce vegetables and herbs all year round, are typically family-owned businesses cultivating up to 40ha and may have up to 10% of their land planted to one or two varieties of culinary herbs. They are frequently located on urban fringes close to central market precincts.

Opportunity growers (existing primary producers and horticulturalists) may grow herbs in some years, and in some seasons, to diversify their business mix, provide continuity of employment for staff or to capture seasonal price advantages. It is thought that these growers account for 5–10% of Australia’s culinary herb production.

Small scale growers, cottage industry and lifestyle growers who grow herbs may have operations of less than 1ha, may rely entirely on family labour and sell only locally or directly to the public. It is estimated these smaller growers account for 5–10% of production.

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Map of current and potential growing regions

Uses

The growth in markets for culinary herbs has been attributed to a number of factors including:

  • renewed consumer interest in fresh, healthy foods
  • an increasing interest among home cooks in multicultural cuisines
  • the increased popularity of television cooking shows.

In response, Australian supermarkets have increased the range of fresh cut herbs available, introduced a range of convenient sized, pre-packaged herbs and shelf stable herb pastes.

Apart from being sold as fresh cut herbs, generally herbs can be used for culinary use as dried herbs, processed into powder for herbal medicines or cosmetic products or processed for essential oils.

The use of mint has been traced back to Greek and Roman times, when it was used in cooking and as an essence in wine. Mint is used extensively in Middle Eastern, Indian, South American and Asian cuisine. It has a sweet aroma and a “cooling” characteristic making it a popular addition to summer fruit punches, iced teas and cocktails. Mint is a popular flavour in confectionery and ice cream, chewing gum and toothpaste. It is also used in personal toiletry items like shampoos and skin care products.

Mint is also a popular herbal remedy for abdominal symptoms including indigestion, nausea, bloating and abdominal pain.

Production Requirements

Growing regions

Mint is grown in all states and territories in Australia. As herbs can be grown in greenhouses there is some flexibility in growing regions, because the producer can control the production environment and soil type.

Soil type

Mints do best in deep, rich soils with a friable texture high in organic matter. The preferred pH range is from 6.0–7.5. Mint has a high water requirement so soils must be deep and well drained, but able to hold plenty of water.

Climate

Mint prefers damp, partly shaded areas. For maximum production, mint requires large amounts of water compared with other crops. To keep soil moist during periods of high evaporation, plantings should be irrigated at least twice a week. During the growth period in summer, plants can require up to 1500mm of water.

Varieties

A number of varieties of mint have been developed for Australian conditions. Depending on production method, location, seasonal planting preferences and target market, a seed company will be able to provide detailed advice about appropriate varieties and fertiliser requirements.

Planting and crop management

There are four main types of commercial herb production systems:

  • broadacre cropping with machine harvesting for manufacturing or seed production
  • intensive in-ground cropping for fresh market
  • hydroponic production for fresh market
  • greenhouse production.

Broadacre cropping is a larger scale operation that would suit an established farmer looking to grow herbs as an alternative crop. Broadacre operations may be 5–10ha in size and are mechanized. They are usually linked to the processing sector, where large quantities of fresh herbs are required for manufacturing pastes or other food products, or producing essential oils (where the oil content is only 1–2% of the raw product).

Intensive in-ground cropping is a popular production system with market gardeners and horticulturalists. While it usually has a lower capital investment cost in terms of harvesting equipment it is quite labour intensive and has a corresponding higher investment in irrigation and packhouse infrastructure.

Hydroponics is the process of growing plants in sand, gravel or liquid, with added nutrients but without soil. The costs of establishing a hydroponic enterprise can be very high and greater technical expertise will be required to crop successfully. However, hydroponics do have some advantages. Pest and disease problems are reduced in comparison to in-ground production. The crops can be grown at waist height, which reduces the effort required in planting, maintaining and harvesting the crops. Nutrient runoff can be controlled or minimised, and as hydroponic growing is ‘soilless’ it enables herbs to be grown even in areas not normally known for agricultural production.

Hydroponic production is not limited to greenhouses, however if using a hydroponics system outside, be aware that rainfall will dilute the nutrients and cause run-off. This may result in negative economic and environmental impacts.

Greenhouses may be expensive to establish but growing herbs in greenhouses allows a certain level of climate manipulation and protects crops from adverse weather events. Greenhouses allow for the extension of growing seasons for a few weeks either side of conventional planting and harvesting. Pests and diseases can also be minimised and crops can be grown on benches at a comfortable height.

Greenhouses can also be extremely useful for propagating planting stock, or for getting stock established early. High technology protected cropping systems using the latest glasshouses have made year round cropping possible in colder locations in the southern states. These systems make it possible to control air humidity; they have advanced boilers with CO2 harvesting; and heat storage systems combined with thermal screens to conserve energy at night and control radiation levels during the day. These systems are very capital intensive, highly sophisticated and heavily reliant upon consistent markets providing stable returns.

All commercial production is propagated from direct sown seed. Planting distance for mint will vary according to the type of equipment used to cultivate and manage the crop. But generally, if planting in an intensive-cropping system, row spacing of 50cm with runners planted 10cm apart within the rows is the standard layout.

Different production systems will have different crop management requirements but some common practices apply.

The soil moisture profile must be managed appropriate to the variety. If the soil is too dry, the herbs will not grow to their potential, they may flower too early, reducing foliage production, or they may fail completely. Wet soil will cause root rots and increases the risk of disease. The soil moisture profile should be checked regularly and the impact of the weather (if growing outside) considered when planning irrigation events. For maximum production, mint requires large amounts of water compared with other crops. To keep soil moist during periods of high evaporation, plantings should be irrigated at least twice a week. During the growth period in summer, plants can require up to 1500mm of water.

Soil nutrition should be managed to ensure optimum growth is achieved. It is important to ensure fertiliser is applied at the right time and in the right dose, and matches the characteristics of the soil as well as the type of herb or variety being grown. The New South Wales Department of Primary Industries suggests that an annual dressing of animal manure will supply mint with a good balance of major and minor elements. Care should be taken not to supply excessive amounts of nitrogen. If soil pH drops below 6.0 it may be necessary to apply dolomite or lime to raise the pH to the desired level.

Crops should be regularly monitored for weeds, pests and diseases, which is best done through regular inspections of the herbs as they grow. Weeds should be pulled out (by hand) in order to ensure no contamination of fresh herbs at harvest.

Weeds, pests, and diseases

Weed control in culinary herb crops is crucial to ensure no contamination by foreign plant material at harvest. Due to the lack of herbicides registered for use in culinary herbs in most states, regular monitoring of crops and hand weeding is the most effective form of weed control.

Mint rust is a serious disease that is caused by the fungus Puccinia menthae Pers. and affects the leaves and shoots. Rust is usually first detected as yellow pustules on the undersides of leaves in early spring. The pustules release spores as they mature, which infect newly developing leaves. This causes the development of powdery brown pustules, which in turn produce very large numbers of infectious spores, initiating a cycle of re-infection that rapidly repeats itself over summer. If not controlled rust will quickly defoliate the plant. The use of disease-free planting material and a sound rotation with other crops will help control the incidence of rust.

Infrastructure Requirements

Infrastructure requirements will vary with the production methods chosen and the scale of the culinary herb operation, but would generally include:

  • tractor
  • irrigation system
  • electricity or diesel pumps to obtain water from a dam, bore, stream, or irrigation channel
  • greenhouse/s
  • hail netting to protect plants
  • spray equipment with separate spray units for pesticides and herbicides
  • trailer and farm vehicle
  • farm shed
  • harvesting equipment (secateurs, bins)
  • cool room for controlled temperature storage
  • sorting/grading and packing equipment (scales)

It is also important to have on hand a good source of consumable supplies such as plant stock, fertilisers, pesticides, which will need adequate storage facilities.

Harvesting & Processing

Culinary herbs are generally harvested by hand to ensure blemish-free produce for the fresh market.

Ideally harvesting should take place early in the morning before the plants wilt, while the temperature is low and plants can be easily cooled to the desired storage temperature. Harvested herbs should be handled carefully to minimise damage and bruising, as this will lead to early deterioration and impact prices.

Mint’s intensity of flavour and aroma is dependent on the level of essential oil in the plant. Oil content is at its maximum at the commencement of flowering.

Once harvested, the appearance and flavouring compounds and essential oil content of the herb will rapidly decline if the plant material is not refrigerated to preserve quality. Temperatures around 1–5˚C will suit most leafy herbs and high humidity around 90–95% in the storage area will help reduce water loss from the harvested material during the cooling process.

Specialist producers invest in temperature-controlled storage technologies as this can greatly extend the lifespan of fresh herbs, and maintain quality of the product. However, this type of storage can be expensive to install.

Plastic wrapping will help prevent the herb from getting dehydrated whilst in cool storage, but be sure to check regularly for signs of any rotting. Sealed packaging, soon after the harvested product reaches storage temperature, will also help maintain moisture levels and conserve shelf life.

If selling to wholesalers, the most common way to pack herbs is to bulk package them in one kilogram boxes or Styrofoam cartons covered with paper or plastic. Approximately 70% of growers and distributors pack their herbs inside perforated polyethylene or polypropylene bags that are then placed in waxed cartons.

Large supermarkets require regular supplies of a very high quality product with an equally high standard of packaging and accreditation to their quality assurance and food safety programmes. All product will have to be packaged according to the supermarkets specifications.

Because all sectors of the wholesale and retail markets for fresh herbs demand reliable long-term supply of high quality product, producers are investing in improved postharvest handling practices. However, some in the industry believe that a lack of knowledge in this area is a barrier to the industry achieving its aims of consistent supply and quality.

Markets & Marketing

It is difficult to import fresh herbs into Australia because of strict quarantine requirements. Australia also imports dried herbs for use in food manufacturing, perfumes and medicines.

When planning to market any horticultural product, it is important to remember that wholesalers and retailers are generally looking for the following attributes from a supplier:

  • a great tasting product
  • high quality, fresh produce
  • on-time delivery and consistency of supply
  • an accredited food safety program.

The horticultural supply chain provides a useful framework for industry entrants to understand the potential marketing structure for culinary herbs.

A typical supply chain for horticultural production has the following linkages:

  • grower
  • packer
  • transporter
  • unloading agent
  • wholesaler/agent
  • (potentially a secondary wholesaler)
  • processor
  • exporter
  • retailer
    • chain retailer (e.g. major supermarket)
    • specialist retailer (e.g. a fruit and vegetable shop)
    • foodservice (e.g. a restaurant)
  • consumer

These are not necessarily listed as a sequential supply chain, for example some growers will bypass packers and wholesalers and sell directly to restaurants or consumers. Wholesalers will also sell to secondary wholesalers, who in turn on-sell to smaller retail buyers and provedores who may supply the food service industry.

Traditionally, wholesale ‘central’ markets in capital cities were the major way to sell and distribute horticultural products. Now the large supermarket chains prefer to deal directly with growers who produce larger volumes or alternatively with packers or agents who consolidate produce from a number of growers to ensure consistent supply.

Growers should actively monitor prices at the wholesale and retail level to understand any seasonal or other price factors that may inform their production system. It is often suggested that one of the best ways to monitor price signals and plan production accordingly is the establishment of good business relationships between the grower and the wholesaler/agent. This can add some transparency around market signals.

All the capital city wholesale markets have price reporting services that sell price reports on a daily, weekly or monthly basis. Because herbs are a relatively small component of the fresh produce business, the reporting is often cursory and slow to react to short term pricing fluctuations. Supermarkets do not publish their purchase pricing and so there is little or no transparency in the herb marketplace.

Success in producing and distributing a quality herb product include attention to pre-harvest management, good initial quality, good postharvest temperature management and reliable packaging to maintain quality.

Risks & Regulations

Risks/challenges

As with all agricultural pursuits, risk is inherent in culinary herb production and specific risks include:

  • unpredictable weather conditions that may affect yield or quality
  • prices falling during the growth period impacting on the returns projected at planting
  • a disease or pest outbreak that reduces yield or quality which may impact the price received, or destroy the whole crop
  • the availability and cost of labour, as culinary herbs are cultivated and harvested by hand
  • the relatively short amount of time available to transport culinary herbs to market before they start to deteriorate
  • the lack of control of post-harvest handling once the crop leaves your property can result in damage and ultimately, wastage
  • the challenges of understanding the marketing of culinary herbs with limited information available
  • not recouping the costs of inputs and capital invested in the crop, like fertiliser, water or staff costs, if the crop fails.

Regulatory considerations

The standard regulatory considerations that apply to all Australian farms, including laws applying to food safety programs for producers and food handling premises (varies from state to state), chemical use and management (varies from state to state), occupational health and safety and transport (including machinery movements and the loading/unloading of harvested product), apply to culinary herb operations. In addition there are a number of regulatory considerations specific to horticultural operations.

Before buying new land to plant crops, a thorough investigation of the land’s suitability for a horticultural enterprise and its cropping or land use history, should be undertaken. This may include identifying a history of chemical contamination (and residue levels) and potential disease risks. Some disease pathogens can survive in the soil for many years, so information about previous disease outbreaks will assist determining which crops are suitable for planting. Some of this information can be obtained from the relevant state agriculture department or local or state planning authority. Prior to purchasing a property for herb production, intending growers should consider undertaking soil sampling and testing for any residual chemicals such as dieldrin or other banned agrichemicals.

If planning to establish additional on-farm infrastructure, like greenhouses or access roads, liaison with the state and local government agencies responsible for planning, native vegetation laws and water licences will be necessary.

Some land use applications will also need to be considered by the relevant local government authority. Approval or a licence to clear native vegetation from land to develop infrastructure will be required from the relevant state department of agriculture, environment or planning. Failure to have the relevant approvals may result in prosecution.

Growers will also be responsible for regularly inspecting their crops for notifiable pests and diseases and reporting any incidence to the relevant state agriculture department.

Horticulture and food production businesses have strict requirements in relation to record keeping, registrations, and accreditations (as well as associated costs) for e.g. quality assurance, food safety, safe use of chemicals, environmental performance and intellectual property. Websites like Freshcare may provide a starting point for understanding these requirements.

Growers may need to investigate the need for minor-use permits if they are planning to use sprays of any type, whether certified organic or otherwise, or conventional spray chemicals on their herb crops. The manufacturer generally registers chemicals and biological agents used in major crops like lettuce or wheat. However, for smaller crops, like culinary herbs, individual growers may have to apply for a minor-use permit from the Australian Pesticides and Veterinary Medicines Authority, (APVMA) which must be regularly reviewed. The APVMA provides information on applying for minor-use permits. If chemicals are used on herbs a withholding period may apply. It is the responsibility of the producer to ensure compliance the withholding period.

All herbs, when sold fresh, dried or processed for either animal or human consumption in Australia, must comply with the Food Code, which is administered by the Federal Government authority, Food Standards Australia & New Zealand (FSANZ) in relation to microbiological contamination and chemical residues. This compliance is a fundamental requirement for all herbs and produce sold. Non-compliance with the Food Code in terms of chemical residues can result in criminal prosecution and the imposition of severe penalties.

All mints are invasive as the plant sends out runners that develop new roots and shoots. Without careful monitoring, mint can take over garden beds, and beyond. For this reason spearmint and peppermint are considered environmental weeds in Victoria and Western Australia. If establishing mint operations in these states, contact the local department of primary industries to discuss required containment strategies.

Publications

Publications/information

Commodity growing guide – Mint NSW Department of Primary Industries (2007)

Mechanisms for managing some important pests of culinary herbs RIRDC Report (2012)

The Australian herb growing industry RIRDC Report (2001)

Prospects for medicinal herbs RIRDC Report (2006)

Establishing a successful small horticulture enterprise: Principles and experiences Victorian Department of Environment and Primary Industries

Establishing a successful small horticulture enterprise: Key things you need to know Victorian Department of Environment and Primary Industries

Vegetable growing and management Victorian Department of Environment and Primary Industries

Other resources

Herb Society (WA)

Queensland Herb Society

Image Gallery

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Mint flowers

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Spearmint flowers - Mentha Spicata