Spicing Things Up
For many beginners, part of the fun of hydroponics is being able to serve something fresh and fragrant to spice up meals and impress dinner guests.
While a succulent tomato with a sprinkling of aromatic basil straight from the hydroponic garden is certainly a good start, it's just that –a start. There are plenty of gourmet flavors that the hydroponic gardener will find easy to grow. Some of our most treasured herbs and spices really are better fresh, and you don't need to be a gourmet chef or a highly experienced gardener to have these growing readily on hand.
Many of the plants from which we obtain spices and flavorings are not delicate plants at all – lemon grass when mature tough and fibrous and can handle a lot of mauling round, pulling apart and crushing to release its lemony lime scented oil. Many of the species of edible ginger that grow from underground rhizomes can handle a lack of water and even humid, over-heated grow rooms with ease.
Even saffron, the most delicate of spices, is adapted to hot dry summers and cold winters, so a comfy grow room or window box can produce a nice harvest of golden strands.
Hydroponic hobbyists have even produced vanilla orchids indoors; although these plants can get quite large and could easily fill a room with their trailing vines.
For those who like Asian inspired dishes, there are a good range of exotic herb and spice plants which mesh well together – Kaffier lime leaves and fruit, fresh ginger, sliced galangal, lemongrass and garlic can all be grown hydroponically in a relatively small space provided they are kept trimmed and compact. For those who like hot spicy curries, chilies, curry leaf and turmeric can also be grown in containers, although they need a little more space than the average herb garden.
And for lovers of delicate dishes saffron, produced by the crocus bulb, is perhaps one of the easiest of all hydroponic spices to grow in a small space, with the advantage of also providing beautiful autumn blooms.
Spice garden basics
Most of the spice and exotic herb-flavoring plants that can be grown hydroponically originate in tropical or subtropical climates. This means they are generally not fussy about day length, but they do like some heat. Most ginger species, vanilla orchids, cardamom, turmeric the curry leaf plant, lemongrass and chilies like year round warmth with an optimum of 70 to 86 degrees F (22 to 30C,) making a well-lit grow room a good choice. Many of these plants can be grown in a heated greenhouse or outdoors in summer and then brought inside to over-winter in containers. Some, like Kaffier lime and lemongrass are ready for harvest year round – the aromatic leaves can be plucked and used in cooking whenever they are needed. Others, such assaffron, need to be harvested at a certain time of year and dried for longer storage.
Many of these plants are perennial or at least, like the gingers, are self perpetuating and continue to grow from rhizomes contained in the growing media. Others, such as lemon grass and garlic, are best started as new offsets or seedlings every year or so.
Setting up a spice garden
A designated spice garden can be a wonderful achievement for someone new to hydroponics and perhaps produces some of the most rewarding crops for the home gourmet. Herbs and spices grown in this way are not only guaranteed to be fresh but also free from contamination with preservatives and many of the agrichemicals which may have been used in production of commercially available spices. Herb and spice gardens are also wonderfully aromatic and attractive as well as being something a little different.
Hydroponic systems for spice gardens should incorporate a large pot, container or grow bed area with plenty of vertical space for the larger plants. The area needs to be divided into the smaller and larger or longer term herbs and spices. Growing media should be free draining – perlite and vermiculite mixtures are great for small 'trees' such as kaffier lime, while cocofibe is a great media for those that develop tubers and rhizomes, such as the different types of ginger and turmeric, making selective harvesting from the plants much easier. Saffron needs a free draining, sterilie media but can be grown in shallow trays or pots since the plants don't grow much taller than around 20 cm.
It's also a good idea to have a small propagation area with a bottom heat pad and some form of misting (even manual) where replacement plants can be raised from seeds, cuttings, rhizomes and bulbs.
Most of these plants like moderate to good levels of light, which is usually sufficient outdoors or in a greenhouse in summer, but indoor grow rooms and low light winter areas need artificial lamps. HPS lighting is great for many of these crops; they can handle much of the heat and humidity of a well lit grow room, although some ventilation is still needed to control disease and allow the plants to transpire.
Specific herb and spice plants The Ginger family (Zingiberaceae) There are a few different species of the Zingiberaceae family used in a huge range of cuisines, all of which grow well hydroponically. The most well known is the traditional ginger spice (Zingiber officinale) we can buy as a rhizome or in powdered form in the supermarket. There is also Myoga or Japanese ginger (Zingibar mioga), of which the young flower buds and leaves are used to flavor soups and various dishes. Another member of this family, galangal or Thai ginger is similar in appearance to ginger, with a much milder flavor, and is used sliced in many Thai dishes.
All gingers are relatively easy to grow provided they have sufficient warmth – optimum is 75F (24C) – high humidity and moderate light, in fact in some climates they can become invasive weeds due to their rampant growth and rate of spread. Thus ginger plants need to be confined to a container when grown outdoors.
Ginger, which is widely used as a spice, is an easy plant to start in hydroponics. The plant can be grown from fresh, healthy rhizomes, which can be purchased at supermarkets, produce stores or Asian markets. The thick, light-brown colored rhizome consists of many knobbly buds which form at the end of each 'branch.' If these are planted into a warm, moist media and given sufficient light they will sprout into large shoots with roots developing from the rhizome.
Rhizomes used to grow new ginger plants should be fresh and firm, not withered looking, which occurs when they have been stored too long. The cut ends of the rhizome can be prone to rotting when planted out. However, these can be dusted with a fungicide powder if necessary.
The new shoots form within a few weeks, and once this has occurred the rhizome in the media will begin to develop new buds and expand outwards producing a good supply of fresh ginger.
Harvesting of the new rhizome growth can be carried out once the plant has become fully established with many new shoots and plenty of active growth.
In hydroponic systems the whole plant does not need to be pulled out – by digging down alongside the plant a piece of fresh rhizome growth can be cut from the main rhizome with a sharp knife and the plant left to continue growing. Young ginger can be harvested after only three months growth for use fresh, although stronger flavor develops in rhizomes that are harvested after six months of development. The delicate young shoots of the ginger plant can also be harvested when around three inches high – these are considered a delicacy in many dishes and in vigorous hydroponic plants a few shoots can be regularly harvested in this way.
Under good conditions, ginger plants can become too large and outgrow their container or pot. In this case the plant can be removed for harvest and small pieces of rhizome used to start a new smaller plant in its place. Young ginger also makes an attractive hydroponic house plant and can be grown in the kitchen or bathroom where warmth and humidity levels help maintain growth rates.
Of the many different type of ginger, Galangal seems to grow particularly well in hydroponics and is very forgiving of new and inexperienced growers. This type of ginger seems more cold tolerant than others and although the foliage might die back in a cool winter greenhouse or outdoors, it resprouts in spring.
Yet another member of the Zingiberaceae family is Turmeric, which like ginger grows from a rhizome which can often be purchased in Asian specialty stores. Turmeric can be grown hydroponically in much the same way as ginger and used with fresh or dried and ground to create the distinctive yellow powdered spice.
In the next articles in this series on spice gardens will examine how to grow exotic saffron, kaffier lime, garlic, chilies, lemongrass and curry leaf.
Lynette Morgan is a regular contributor to The Growing Edge Magazine. She is co-owner of Suntec Hydroponic Consultants in New Zealand.
