Hydroponic & Container Basil Guide

Unlike some field crops that can grow with little attention for extended periods of time, hydroponic crops, basil included, require daily management and will do best when environmental variables are tailored to crop-specific needs. Of primary importance are temperature, pH, light, daily light integral (DLI), electroconductivity (EC), and nutrient composition. In general, basil prefers warm temperatures, a moderately acidic pH, and relatively low EC levels, and responds well to high light levels. Specific requirements can vary, however, depending upon the growing system, time of year, and other factors. We recommend the following general conditions for hydroponically grown basil:

• Temperature: 65–70°F (18–21°C).
• pH: 5.8–6.2 (slightly higher in aquaponic and organic systems).
• Light: Minimum 14 hours per day.
• DLI (Daily Light Integral): Minimum 12 mol per m² per day or higher; basil performs well with high light levels.
• EC (Electroconductivity): 1.0–1.4mS/cm, depending on the season; during winter, crops need a higher EC than during summer.
• Nutrient Solution: Choose a solution specific to herbs and leafy greens and appropriate for your water type, and follow package directions to achieve the EC level listed above.

For more information on monitoring and managing nutrient and light levels, take a look at our comprehensive article on Hydroponic Seed Starting for Healthy Hydroponic Seedlings.

If you are new to hydroponic growing, you may also wish to read our Introduction to Hydroponics, which covers the basics of the most common hydroponic growing systems.

It is advisable to grow basil in isolation from other crops so that you can adjust the nutrient solution and other environmental variables as needed; basil grown under conditions optimized for another crop may not perform well.

We encourage you to conduct your own on-site trials to determine the input levels and environmental conditions that work best in your growing system.

Most commercial growers use 3–6"-diameter pots for retail herb production. For basil, we recommend a 4"-diameter pot to provide a balance between efficient use of growing space and producing plants of a size optimal for market appearance and value.

Seeds can either be sown directly into the retail container or into a plug tray and after 2–3 weeks of growth, transplanted into the retail container to finish.

The seeding rates (number of seeds per container) that we recommend below represent a wide range: Using fewer seeds will produce an attractive container, provided the plants are grown under optimal conditions, with plenty of light, space, and time for plants to fill out. Using more seeds per container will produce a fuller appearance for finishing at an earlier stage of production, but the plant will outgrow its pot sooner than a single plant would.

For additional cultural recommendations, refer to our Basil Key Growing Information.

Nearly all basil types and varieties can perform well in hydroponic and container growing systems, but which ones will perform best for you? Here is a list of characteristics that we will discuss below. These characteristics vary between types and varieties of basil:

• Growth rate
• Disease resistances
• Plant habit
• Leaf types
• Yield
• Preferred uses
• Flavor–aroma profile

By considering each one of these features, from production needs to market demand, you'll be better prepared to match your system to the best basil varieties for your desired outcome. Here is some guidance to help you get your container/hydroponic basil production off to a successful start.

Sleeved and ready for market, these 'Genovese' basil plants were grown using an ebb-and-flow table.

Image courtesy of Paul Gallione, Johnny's Territory Sales Representative (retired).

When selecting a variety, it's important to consider how you plan to market the final product. There are several primary ways that full-size (non-microgreen), container- or hydroponically-grown basil is marketed:

• Live plant with growing medium still attached.
• Live plant in nursery container/pot.
• Individual leaves or bunches packaged in bag or plastic clamshell container.
• Baby-leaf crop grown in hydroponic raft system, harvested at 4–6" in height, packaged in bag or plastic clamshell container (less common end product).

Placing the live product within a protective sleeve can help prevent plant damage at market and extend shelf life.

For live plant sales, varieties that produce compact, attractive, full, and uniform plants are ideal.

If individual leaves or bunches are the primary end product, however, variety selection is driven more by leaf type, yield, and flavor–aroma profile than by plant habit.

Regardless of the end product, slow-to-bolt varieties extend the harvest window and fast-growing varieties speed crop time for a faster turnover.

Side-by-side-comparison of the two primary types of green basil: Genovese (left) and Italian Large Leaf (right).

There are two primary types of green basil, each with distinguishing flavor, yield, and leaf type features.

• Genovese basil is prized for its classic pesto flavor and characteristic, heavily cupped, spoon-shaped leaves. Genovese is largely the preferred type for culinary use.
• Italian Large Leaf basil is known for being highly productive. Plants are dense and produce large, pointed, rugose (wrinkled) leaves that are typically thicker and more durable than the leaves of Genovese type varieties. That durability, coupled with strong yields and quick growth, are the reasons why some growers prefer the Italian Large Leaf type, although its lighter green leaves and sweeter flavor profile is considered less refined than those of the Genovese type. Discerning basil consumers will pick up on the stronger notes of anise or cinnamon commonly present in this type of basil.

In addition to the standard green basil types commonly grown in North America, there are Red/Purple, Citrus, Asian/Thai, and Lettuce Leaf basils. Each offers specific features and qualities of color, flavor, and culinary use.

For more information, see our tech sheets on Basil Downy Mildew Awareness & Prevention and Basil Pests & Diseases. Learn how plant breeders today are developing superior organic basil options in our interview, Basil Downy Mildew and Prospera^® DMR Basil • Breakthrough Breeding Innovation Provides Solutions.

The two most common diseases of basil are basil downy mildew (DM), a water mold, and Fusarium wilt (F), a fungus. Selecting disease-resistant varieties can be helpful when disease pressure is a problem.

• We offer a series downy mildew-resistant (DMR) varieties that offer a stronger level of resistance than the first-generation varieties. The pathogen is a rapidly evolving one, however, and multiple strains (or races) of downy mildew have been identified in different geographic regions, so we suggest trialing a few different varieties to see which work best for your region.
• We recently connected with 3 individuals whose line of work puts them face-to-face with basil downy mildew. Read our report of our interview on variety development, grower success, and monitoring, reporting and management: Basil Downy Mildew and Prospera^® DMR Basil • Breakthrough Breeding Innovation Provides Solutions.
• For more information on identifying and preventing this disease, see our Basil Downy Mildew Prevention Tech Sheet.
• All of our basil seed lots are lab-tested to confirm the absence of seedborne Fusarium, and we also offer a range of Fusarium-resistant varieties.

Refer to the following resources for additional guidance on growing hydroponic and container basil.

• Downloadable, printable version of this article • 4-pp Brochure (PDF)
• Basil • Key Growing Information
• Basil Downy Mildew Awareness & Prevention • Tech Sheet (PDF)
• Basil Pests & Diseases • Tech Sheet (PDF)
• Basil Downy Mildew & Prospera^® DMR Basil • Breakthrough Breeding Innovation Provides Solutions • Interview