Hydroponic Herbs

Thinking of growing herbs? We recommend that you try hydroponics. This method offers greater benefits compared to growing herbs in conventional soil. Without soil, roots receive their nutrient solution immediately, water stress is never an issue, and herbs remain small and efficient – so plants are able to convert energy into their top growth. It’s easy and, best of all, you will have fresh, flavorful herbs throughout the year.

Some of our favorite hydroponic herbs include:

  • Basil
  • Parsley
  • Sage
  • Coriander
  • Oregano
  • Rosemary
  • Mint
  • Dill
  • Thyme
  • Chives
  • Chamomile

Benefits of Growing Hydroponic Herbs:

  • Outdoor plants are subject to many variables, including temperature, precipitation and lighting. Since herbs thrive in a mild, consistent and controlled environment, indoor hydroponics is a preferred method of growing. Normal indoor room temperatures are ideal, so this makes growing herbs indoors easier and less vulnerable to temperature fluctuations often found in outdoor growing environments.
  • Overwatering and underwatering is a constant challenge with soil mixes. Too much or too little water may result in the demise of your herbs. In contrast, hydroponic systems allow for a consistent supply of water and nutrients, eliminating the stress and guesswork involved with growing herbs in soil.
  • Not only will you avoid the mess caused by having a soil mix, growing herbs using hydroponics can result in a 20%-50% faster growth rate. That means more fresh herbs for your enjoyment, throughout the year.
  • Pests love soil. Gnats, flies, and other insect infestations can be a constant problem for those who use a soil mix to grow their plants. Since hydroponics uses no soil, this becomes less of a concern. No soil-borne diseases, no weeding, and the need to introduce those insecticide sprays into your indoor environment is less likely.
  • If those advantages haven’t sold you on growing your herbs with a hydroponic system, consider this. Research at The University of Minnesota concluded that hydroponically grown herbs have 20-40% greater amount of aromatic oils when compared to herbs grown in conventional fields. This ensures that your herbs are of better quality and have a more robust flavor versus herbs grown in soil. So let’s get started!

Requirements for Growing Hydroponic Herbs:

Consideration for growing hydroponic herbs include: light, nutrients, temperature, humidity, and pH level. Once these factors are controlled, hydroponics provides a less time-consuming and superior growing medium versus conventional soil.

While propagating herbs from cuttings is a viable option, starting your herbs from seed is the most popular method for growing hydroponic herbs. Moistened propagation cubes work well for seedlings, as does a conventional soil mix. Germination typically takes 1-3 weeks. Once the seeds are of adequate size and are displaying their true leaves, the plants may be transported to your hydroponic grow system. It should be noted that seed germination is difficult when growing lavender, bay leaf, rosemary, white sage, and flavored mint (such as chocolate mint or orange mint). In these cases, a plant from a cutting (or an established plant bought from a garden center) will likely be more successful than growing from seed.

Herbs need – at the very least – 6 hours of bright, unobstructed sunlight per day. A south-facing window may provide adequate lighting for herbs. Rotating the plant to ensure all sides receive sufficient coverage is advisable. Since many plants – including herbs – thrive on up to 10-12 hours of sunlight per day, grow lights are recommended for extra supplementation, especially if your plants are not receiving the minimum natural sunlight to remain healthy. Standard fluorescent lamps may be sufficient, but their yield is less effective compared to modern LED grow lights. High intensity discharge lights [HID] are also effective – especially metal halide, which are superior for growing leafy herbs. Since grow lights with blue spectrum lighting encourage lush, bushy growth in many varieties of herbs (such as basil), grow lights with blue spectrum capability may be the best choice to grow your hydroponic herbs.

Nutrients – specifically designed for hydroponics – are another key component of growing hydroponic herbs. Combining fertilizer and water create the “nutrient solution.”  It is recommended to drain, clean and re-add a new nutrient solution to maintain optimal conditions. This process should be done at least once a month, although more frequently is encouraged. Methods for providing the nutrient solution include the Passive method (which allows you to decide when and how much nutrient solution a plant needs, without the use of pumps and timers), the Flood and Drain method (when trays and pots are flooded with the nutrient solution using a pump), a Drip System (timer-controlled method using a pump to drip nutrient solution on to the plants), the Nutrient Film Technique (NFT) and the aeroponic method.

There are various mediums to choose from when growing your herbs hydroponically. Some of the most popular include coconut coir, lightweight expanded clay aggregate (L.E.C.A), perlite, vermiculite, lava rocks, and oasis cubes, as well as sand and gravel.  These mediums act as an anchor to the plant, but do not provide the essential nutrients for the plant’s health. Thus, the grow medium you choose is of lesser importance than that of maintaining a continuous supply of nutrient solution.

Room temperatures ranging in the 70-75-degree range are ideal, along with a relative humidity level around the 40-60% range.  As with all hydroponic gardening, maintaining adequate ventilation for your herbs is important. Oscillating fans, as well as ceiling fans, work well. pH levels should be consistently checked to maintain a healthy range between 5.5 and 6.8, depending on the type of herb you are growing. See table below:

pH/PPM/cF chart for Hydroponic Growing

Herbs pH cF PPM
Basil 5.5 - 6.5 10 - 16 700 - 1120
Chicory 5.5 - 6.0 10 - 16 700 - 1120
Chives 6.0 - 6.5 10 - 16 700 - 1120
Fennel 6.0 - 6.5 10 - 16 700 - 1120
Lavender 6.0 - 6.5 10 - 16 700 - 1120
Lemon Balm 6.0 - 6.5 10 - 16 700 - 1120
Marjoram 6.0 - 6.5 10 - 16 700 - 1120
Mint 6.0 - 6.5 10 - 16 700 - 1120
Mustard Cress 6.0 - 6.5 10 - 16 700 - 1120
Parsley 6.0 - 6.5 10 - 16 700 - 1120
Rosemary 6.0 - 6.5 10 - 16 700 - 1120
Sage 6.0 - 6.5 10 - 16 700 - 1120
Thyme 6.0 - 6.5 10 - 16 700 - 1120
Watercress 6.0 - 6.5 10 - 16 700 - 1120

Keeping the plants bushy allows herbs to be more productive. Pinching off the tops when your plant reaches 6-12” tall will prevent them from becoming too leggy. Herbs do not require a lot of attention once your hydroponic routine is in place, and are a perfect choice for those who want to grow fresh produce all year long in a controlled indoor environment.

The Herbs

hydroponic basil herb plant
Photo by aldenchadwick

Basil

  • basil is a bushy herb and can grow 12-24” tall
  • can be started from seed or from a cutting
  • daytime temperatures should range from 70 – 80 F
  • 65 F being the lowest nighttime temperature to remain healthy
  • good air flow is essential for the plant to remain vigorous
  • up to 10-12 hrs of daily light is recommended (supplement with grow light, if necessary)

Basil is – by far – the most popular herb grown in Europe, accounting for roughly 50% of the total herb market in that continent.  Americans also have a love affair with growing basil, as do those in Asian countries.

Basil, referred to as the “King of Herbs,” is thought to be native to India, where it has been cultivated for over 5,000 years. It plays a major role in both Italian and southeast Asian cuisine, adding a flavor infusion which closely resembles anise.  Most varieties of basil have a bold – yet sweet – smell. Italian cuisine is famous for their use of sweet basil (Genovese basil), and basil is one of the main ingredient found in Italy’s famous pesto sauce. Asian cuisine prominently features the use of Thai basil, holy basil, and lemon basil.  To prevent the flavor from being destroyed under high heat, basil is added in at the last moment of cooking to maintain the integrity of its flavor.

With the recent “locally produced” movement, restaurants have discovered the joys of growing their own hydroponic herbs, using homegrown produce to add a fresh twist to their menus. Basil is among the most popular herb grown for this purpose. Favorite types of culinary basil for hydroponic production include sweet basil, Thai lemon basil, globe basil, lettuce leaf basil, cinnamon basil, purple basil, and Siam Queen Basil.

hydroponic parsley plant
Photo by Bruce Guenter

Parsley

Parsley is an herb, native to the Mediterranean region of southern Italy, Tunisia, Greece, and Algeria.  These days, parsley is grown in all regions of the world, making it one of the most popular herbs to cultivate. American, European, and Middle Eastern cuisine incorporate parsley into their cuisine, and is often used as a garnish. It is not uncommon to find fresh green chopped parsley sprinkled on top of dishes served at restaurants. Parsley has two main groups: curly leaf and Italian (flat leaf). Because of its decorative appearance, curly leaf is often the variety chosen for garnishment. Italian parsley is the variety preferred by gardeners, and is one of the most popular herbs in the culinary arts. Parsley makes a fantastic choice for first-time hydroponic herb gardeners.

Rosemary plant
Photo by ndrwfgg

Rosemary

Rosemary is a popular culinary hydroponic herb. Native to the Mediterranean, rosemary’s aromatic, needle-like leaves are a highly-prized ingredient in beauty products and the culinary arts.  The fresh or dried evergreen leaves are traditionally used in Italian cooking as a uniquely astringent flavor-enhancer. Herbal tea is often made with the leaves of a rosemary plant. As previously noted, Rosemary does not propagate well from seed. Thus, starting from a cutting – or buying an established plant – has a higher success ratio than starting from seed.

Thyme

Thyme is another evergreen herb worthy of growing hydroponically. Ancient Greeks burned it as incense, Ancient Egyptians used it for embalming, and many cultures have used thyme for medicinal and ornamental purposes. And of course, thyme can be used to enhance flavors of any dish. Since it has a shelf-life of less than one week, growing your own thyme ensures that you will have a fresh crop within an arm’s length.

hydroponic mint plant
Photo by stevendepolo

Mint

Mint is one of the most recognized and popular hydroponic herbs to grow. With its characteristic aroma, fresh and sweet taste, mint is hard to resist. Between 13 and 18 species are thought to exist.  Mint display leaves of various colors – from grey green to dark green, green and purple, to sometimes blue and pale yellow. Flowers on mint are typically shades of white to purple. The most common and popular mints for commercial cultivation are spearmint, peppermint, apple mint, and Scotch mint. Besides its applications in cosmetics, medicines, insecticides, and aromatherapy, mint is prized in culinary circles. From sweets to refreshing teas, mint is one of the most popular hydroponic herbs to cultivate.

hydroponic herb dill plant
Photo by thomas pix

Dill

Dill leaves are another prized herb that is worthy of growing in your hydroponic garden. Fresh and dried dill leaves are popular additions to the cuisines of central Asia and Europe. Dill has aromatic, fern-like leaves, which complement dishes ranging from seafood to soups.  Like thyme, harvested dill loses its flavor quickly. Thus, using when fresh – or freezing drying – ensures that the full flavor stays intact.

hydroponic herb sage plant
Photo by quinn.anya

Sage

Sage is an evergreen herb with blue to purple flowers, and grayish-colored leaves. A native to the Mediterranean region, sage is now widely grown all over the world.  Sage is used in medicine, especially for helping those with digestive and memory problems, as well as people who suffer from depression. It is also a common addition to other products, ranging from incents to antiseptics. Because of sage’s subtly sweet flavor, it is highly-regarded in the culinary world as a flavor enhancer. This makes sage a popular choice for those who grow hydroponic herbs.

hydroponic herb coriander plant
Photo by flikr

Coriander

Coriander, also known as cilantro and Chinese parsley, is native to southwestern Asia, southern Europe and northern Africa. Greeks have cultivated cilantro for thousands of years, and early American settlers cultivated the herb as early at 1670, making it one of the first plants to be grown in the colonies. The fresh leaves, as well as the dried seeds, are traditionally in cooking. However, the entire plant is edible. Coriander would make a great addition to your hydroponic herb garden.