Hydroponic methods and indoor gardening allow a world of exciting cuisines to be experimented with by growing a diverse range of popular and lesser-known ethnic crops. By dialing up just the right climatic conditions, nutrients, and some cultural know-how, some popular as well as slightly more unusual fruits, herbs, and vegetables can be grown. Mexican cuisine crops are ideally suited to warm, brightly lit indoor gardens and can bring an aromatic and spicy punch to many dishes. With a base of succulent tomatoes, fiery chilies, exotic tomatillos, combined with familiar herbs such as cilantro and the more acquired tastes of epazote and papalo, Mexican crops are both exciting and highly productive to grow hydroponically.
Mexican Fruiting Crops
The mainstay of many Mexican dishes are of course tomatoes, which are native to South America, but to maximize flavor, the selection of tomato variety is important. Mexico produces both red tomatoes and green tomatoes (tomato verde) for local markets, and both have different culinary uses, with green tomatoes usually cooked and most often fried during preparation. Green tomatoes are simply unripe fruit that haven’t gone through any color change, however, there are a few heirloom varieties that remain green when ripe (such as green zebra). Vine ripened red tomatoes most commonly utilized in Mexican cuisine, are “meaty” types with high levels of solids such as beefsteak varieties. The sweet cherry types are also popular and perform particularly well under hydroponic production.
Tomatillos (Physalis philadelphica), also known as Mexican husk tomato, and Mexican groundcherry produce small greenish yellow or purple fruit inside a papery husk which is a staple of Mexican cuisine. Tomatillos have been cultivated in Mexico since pre-Columbian times and are the main ingredient in salsa verde. While green tomatillos may look a little like an unripe tomato, the flavor is completely different. Young fruit is often quite tart, but as they ripen, a more fruity, savory, and completely unique flavor develops with a firm, if somewhat seedy flesh. Tomatillos can be grown alongside tomatoes and chilies on the same nutrient solution as these all prefer similar warm temperature conditions with an optimum of 79°F and moderate to high light levels. There are several tomatillo varieties to select from with the most productive for hydroponics being Toma Verde, which produces almost golf ball-sized green fruits. A number of smaller fruited, heirloom, purple-skinned types also exist which are slower to mature but highly decorative to grow. While the green-skinned tomatillo varieties are fairly tart in flavor, the darker purple types are sweeter and high in pectin and may be used to make preserves and jams. Most tomatillo varieties will need support as these grow to a similar size as large capsicum plants (up to five feet) and will produce a profusion of husked fruit. It’s also advisable to grow at least two to three tomatillo plants in a closely spaced group to assist with cross-pollination. Fruit is ready for harvest when the husk turns a papery tan and starts to split open at the sides.
Chili peppers originated in Mexico and Central America and the fruit provide not only heats of varying degrees, but also intensive color, flavor, aroma, and texture, making them a very versatile plant. While there are a number of Mexican chili types, the main varieties grown hydroponically are habanero, poblano, mulanto, and jalapeno. The heat experienced from eating chilies comes mainly from compounds called capsaicinoids, although other pungent compounds have been identified in hot capsicum fruit. What gives hydroponic growers a major advantage when it comes to growing Mexican chilies is the pungency of the fruit, and even the flavor, can be manipulated somewhat by the growing conditions provided. The concentrations of capsaicin in the chili fruit increase with plant stress factors such as a lack of moisture, high temperatures, high electrical conductivity (EC), and high salinity. Capsaicin concentrations also increase throughout the development of the fruit and are always highest at maturity. So, allowing chilies to ripen and fully mature on the plant (even to the point of starting to shrivel) will maximize the heat factor.
Chili plants can be grown in a wide range of hydroponic systems, although media-based systems are most commonly used as some chili types can grow into large plants at maturity. For NFT, the smaller, bush types of chili are often a better choice and these may need support if the plants become tall and lanky under low light. The best way to obtain plants is to raise these from seed, which germinates readily between 72-82°F in an inert media such as stonewool or small pots which can be later transplanted into the hydroponic system without too much root disturbance. After germination, seedling temperatures can be reduced back to 68-77°F and light levels gradually increased to harden off seedlings before transplanting. For strong flowering and fruit set, the night temperature should be a little lower than the day temperature with an optimum of 77°F during the day and 64-68°F at night. Chilies, while self-pollinating, do benefit from some pollination assistance such as gently tapping or shaking the plants when in flower to help release the pollen.
Most chili types perform well in standard grow and bloom hydroponic nutrient products. Electric current levels should be between 0.8-1.0 for seedlings, gradually increased to an EC of 2.0 before planting out. For those looking to intensify heat, increasing the EC up above 3.0 and allowing the growing media to dry slightly between irrigations will help concentrate flavor and heat in the fruit, but may reduce yields somewhat by lowering fruit fresh weight.
Mexican Herb Crops
Like many cuisines, Mexican dishes make use of a wide range of native and introduced herb and spice crops. Some are well known hydroponic crops such as cilantro (leaf coriander) and mint, while others are new flavor sensations that can really bring the taste of Mexico into dishes which are already old favorites. Epazote and papalo are two such Mexican herbs that perform well under hydroponic cultivation, take up minimal space in an indoor garden, and are relatively trouble-free to grow.
Epazote (Chenopodium ambrosioides) is a classic Mexican herb, little known in the rest of the world and with a flavor profile that can be somewhat challenging to the uninitiated, and an acquired taste. Epazote is often considered to be an essential ingredient in many traditional Mexican chili and bean dishes and has a flavor described as camphor or turpentine-like with a strong aroma. While its usual flavor doesn’t seem that attractive on its own, it does add something unique and special to many Mexican dishes that make it worth trialing in hydroponic herb gardens. Easily grown from seed, epazote is a small but rapid growing herb requiring temperatures between 64-79°F, moderate to high light and with similar nutritional requirements to other hydroponic herbs such as basil and cilantro. Being easy to propagate from seed and an annual crop, epazote grows exceptionally well in NFT and other solution culture systems and can be combined with lettuce, herbs, and other small vegetables.
Cilantro (Coriandrum sativum) is sometimes referred to as leaf coriander, Mexican parsley, or simply as coriander, and is a quick-growing, warm-season annual herb. Cilantro and coriander are the same plant and are both used in Mexican cuisine, however, cilantro refers to the flat, fan-shaped leaves, while coriander refers to the seeds that are ground and used as a spice. Cilantro leaves have a characteristically different aroma and flavor profile than the ground seeds, but both are frequently used in the same dish. Cilantro is a fresh herb with a limited shelf; its flavor and aroma diminish with shipping and storage and the delicate foliage is easily damaged. For this reason, it is an excellent herb to grow in an indoor garden to be harvested just before use when its flavor quality is highest. Since cilantro has a habit of going to seed (bolting) fairly rapidly, it’s important to select cultivars that will not only grow large, quality foliage but are also slow to bolt in the warm protected environment of an indoor garden. Varieties such as calypso, santo, and marino are well-suited to hydroponic production being slow to bolt and allowing two to three harvests or cuts before plants need to be replaced. Cilantro seed is large, rounded, and easy to handle and is best sown into individual cubes, cells, or pots of sterilized, free-draining substrate as seedlings are not suited to transplanting. Germination occurs within five days at 68-78°F, with seedlings requiring warmth (more than 68°F) and moderate light levels to prevent elongation and tall, weak growth. Under hydroponic production many growers sow several seeds into each planting site or pot and grow these mini bunches for just a few weeks before cutting. For small-scale indoor gardens, cilantro can be harvested at any stage from young seedlings (microgreens) through to mature plants depending on the flavor intensity required. Younger plants are more tender and the flavor milder, while older plants, particularly those about to flower, develop stronger, sometimes slightly bitter taste.
Papalo (Porophyllum ruderale) is a lesser known, ancient Mexican herb which predates the introduction of cilantro and appears to be well-suited to hydroponic herb gardens and NFT systems in particular. The flavor of papalo is similar to a combination of cilantro, arugula, and lime with an aromatic, yet nutty, sharp flavor that is particularly well-suited to incorporating into salsas and many other Mexican dishes as a cilantro alternative. Papalo is a heat-loving plant and has less tolerance to cooler conditions than cilantro, (and is thus sometimes called summer cilantro), however, its bolder and more complex flavor makes it a great addition to tomato, bean, and chili dishes. Papalo, with its higher degree of heat tolerance, is also a great plant to grow in conditions where cilantro typically bolts and goes to seed rapidly. The aromatics and flavor of the papalo foliage mostly originate from the large oil glands which look like dark green spots on the undersides of the leaves and are a distinctive characteristic of this unique herb. Papalo comes in two different leaf forms: narrow and broad leaf, with the broad leaf being more suited to hydroponic production and having a more palatable flavor. Papalo seeds are available from seed supplies, however, germination can be somewhat slow, so buying in small plants is another option for hydroponic systems.
For those with very limited space, epazote, papalo, and cilantro can be grown as microgreens, harvested in the seedling stage after the development of two to four leaves. Even at this delicate stage, these herbs develop their characteristic flavor in a milder form, well-suited to many culinary uses
Setting aside some space for Mexican cuisine crops adds an extra dimension of flavor to a hydroponic garden. While we are all familiar with the traditional tomato and chilies, growing a few tomatillos alongside these perennial favorites will give months of great tasting fresh salsa ingredients. Experimenting with a few of the more unusual Mexican herbs such as epazote and papalo is also one way of obtaining that truly authentic flavour, and there are also many lesser known Mexican herbs which are worth some investigation.