Hydroponic Crop Selection: An Easy Guide

Hydroponic Crop Selection - Crop

Hydroponic Crop Selection Chart

Greens

Arugula

Arugula is a brassica, like mustard or kale. It carries a spicy punch in a tender leaf, making it a great addition to salads, pizzas, and sandwiches. Some varieties are spicier than others, with the Rocket variety being considered the spiciest of the three most popular (astro, rocket, and sylvetta). Though arugula grows like lettuce (some varieties are ready for harvest in just 3 weeks) and is in the family of brassicas, it’s often considered an herb.

 

Growing Arugula

Planting: Germinate from seed

Harvesting: Full harvest

Pests and diseases: Rare, most common are aphids and flea beetles. Disease problems rarely occur.

pH range: 5.5–6.5

EC/PPM: 0.8–1.4/400–700

Light hours: 12–18

Temperature Range: 50–75°F (10–24°C) Ideal: 65°F (18°C)

 

Bok Choy

Bok choy—also called white Chinese cabbage, Chinese chard, Chinese mustard cabbage, and pak choi, among others—belongs to the leafy vegetable pak choi family of Chinese brassicas. Bok choy has white or green, thick, crunchy stems with light to dark green wide leaves. All parts, stems, and leaves can be eaten, with the leaves being soft and buttery, while the stalks are crunchy and slightly bitter. Size can vary from 4 to 12 inches (10–30 cm) tall—bigger if lengthier grow-out times are practiced.

 

Growing Bok Choy

Planting: Germinate from seed

Harvesting: Full harvest

Pests and diseases: Rare, most common are aphids and powdery mildew

pH range: 5.5–6.5

EC/PPM: 1.5–2.5/750–1250

Light hours: 14–18

Temperature Range: 55–75°F (13–24°C) Ideal: 65°F (18°C)

 

Kale

Kale has been hailed as a super food and has found its way into home and restaurant menus alike. There are a lot of different varieties of kale, like the scaly looking dinosaur kale (also called Tuscan kale) and curly kale. Some varieties display shades of red and purple, like Russian red kale. Kale’s wide EC range makes it compatible with many different herbs and greens. Fortunately, kale is another crop that when grown indoors is targeted by only a few pests and diseases, such as aphids and powdery mildew.

 

Growing Kale

Planting: Germinate from seed

Harvesting: For partial harvest, only take 30% of the plant at one time

Pests and diseases: Rare, aphids and powdery mildew most likely indoors

pH range: 5.5–6.5

EC/PPM: 1.6–2.5/800–1250

Light hours: 14–18

Temperature Range: 45–85°F (7–30°C) Ideal: 65°F (18°C)

 

Lettuce

Lettuce is one of the most popular crops in the world. This cool season crop grows sweet and tender, and it’s a perfect addition to any fresh dish. Lettuce grows well in almost any gardening system, whether hydroponic, aquaponic, or traditional soil gardens. It takes up relatively little space and has a short (5–6 weeks from transplant or 9–11 weeks from seed) growing cycle.

 

Growing Lettuce

Planting: Germinate from seed

Harvesting: Harvest lettuce as a whole head (or whole plant) and store at 32–35°F (0–2°C). Keep temperatures as consistent as possible.

Pests and diseases: Aphids, leaf miners, and powdery mildew

pH range: 5.5–6.5

EC/PPM: 1.0–1.6/500–800

Light hours: 14–18

Temperature: Range: 45–75°F (7–24°C) Ideal: 65°F (18°C)

 

Mustard Greens

Mustard greens are another member of the brassica family (a relative of kale and cabbage). The ruffled leaves of mustard taste similar to radishes and can add a spicy bite to a salad or a sandwich or can be eaten by themselves (often steamed). Mustard is often cultivated for its seed, which is used in brown mustard (the condiment) and has been used for centuries in folk remedies for aches, arthritis, and even to promote cow milk production in some areas of the world. A favorite among many growers is the Southern Giant Curled variety; however, many varieties have been bred with different flavors and colors ranging from green to dark purple.

 

Growing Mustard Greens

Planting: Germinate from seed

Harvesting: For partial harvest, only take 30% of the plant at one time

Pests and diseases: Potential pests and diseases are minimal—cabbage loopers, flea beetles, cabbage worms, and clubroot

pH range: 5.5–6.5

EC/PPM: 1.2–2.4/600–1200

Light hours: 14–18

Temperature Range: 50–75°F (10–24°C) Ideal: 65°F (18°C)

 

Swiss Chard

Chard is a French green popular in greenhouses and kitchens around the world. The tender leaves add freshness and a mild buttery flavor to dishes like soups, salads, or on BCG (beet, chard, and goat cheese) sandwiches. Chard leaves grow on elegant stems that range in color from red to yellow and white and can get larger than a dinner plate. Chard is a great crop for beginners due to its easy-to-grow nature. This cool season crop is not only tasty and easy to cook, but it’s also easy to grow in almost any hydroponic system.

 

Growing Chard

Planting: Germinate from seed

Harvesting: Only harvest 30–35% of the plant, leaving the rest of the plant to support another harvest

Pests and diseases: Rare, potential pests and diseases include aphids and powdery mildew

pH range: 5.5–6.5

EC/PPM: 1.6–2.3/800–1150

Light hours: 14–18

Temperature Range: 55–75°F (13–24°C) Ideal: 65°F (18°C)

 

Herbs

 

Basil

There are dozens of basil varieties, from spicy bush basil to lemon basil and Thai basil, all of which bring a delightful twist to any dish when paired well. Favorites are the classic sweet basil, Genovese basil, and dwarf basil. Basil produces large harvests and is so fragrant and delicious you won’t want to stop growing it once you start.

 

Growing Basil

Planting: Germinate from seed or start from clone

Harvesting: You can start picking leaves when the plants are at least 6–8 inches (15–20 cm) tall

Pests and diseases: Potential pests include aphids, thrips, and whiteflies. Diseases include root rot, leaf spot diseases, and downy mildew.

pH range: 5.5–6.5

EC/PPM: 1.6–2.2/800–1100

Light hours: 14–18

Temperature Range: 65–90°F (18–32°C) Ideal: 75°F (24°C)

 

Chives

Common chives are the variety most used. A few other varieties, like garlic chives and Chinese chives, are also available. Chives are a tough crop that will survive a wide range of temperatures and can even go without water for a while without it impacting quality. Chives are also rarely infected with diseases and rarely targeted by pests. Chives propagate rapidly from roots and can be planted by division (this is ideal, since germination times on chives are relatively long). 

 

Growing Chives

Planting: Germinate from seed or from root by breaking apart mature plants and replanting

Harvesting: Harvest every 2–3 weeks by cutting the plant to 1–2 inches (2.5–5 cm) from the crown

Pests and diseases: Rare, most common in hydroponic systems are fungus gnats

pH range: 5.5–6.5

EC/PPM: 1.6–2.2/800–1100

Light hours: 14–18

Temperature: Range: 55–80°F (13–27°C) Ideal: 70°F (21°C)

 

Cilantro (Coriander)

Cilantro (coriander) can be a tricky crop to grow since it bolts very easily, especially in hot conditions. If bolting is triggered, trim the bolts, and adjust environmental conditions. Be aware that the flavor of the greens becomes more bitter and harsh once the plant has bolted. You can purchase slow bolting seeds to minimize the potential for crop failure.

 

Growing Cilantro (Coriander)

Planting: Germinate from seed

Harvesting: Harvest completely cutting at the base of the plant

Pests and diseases: Cilantro (coriander) can be attacked by aphids and powdery mildew

pH range: 5.5–6.5

EC/PPM: 1.2–2.0/600–1000

Light hours: 14–18

Temperature Range: 50–80°F (10–27°C) Ideal: 65°F (18°C)

 

Fennel

A mildly sweet herb with a taste reminiscent of anise, fennel is edible both as bulbs and greens. The greens may be harvested once before a full-plant harvest a few weeks later. Fennel prefers a lower EC and moderate pH. Fennel is a hardy plant—it often proves to be drought tolerant, heat tolerant, and cold tolerant. Fennel rarely struggles with pests if it’s kept healthy, although aphid infestations could affect the crop. Fennel has a wider range of germination rates, from about 60% to 90%. Be sure to get good seeds. Seeds take 1–2 weeks to germinate and are typically ready to plant 3–5 weeks later. The bulbs can be harvested as soon as you want, but 0.5 to 1 lb (227–454 g) bulbs are typically sold at supermarkets. From seedlings, it takes most plants 6–8 weeks to reach the harvesting size.

 

Growing Fennel

Planting: Germinate from seed

Harvesting: At first harvest only take 30% of the greens, and take the full plant on the second harvest

Pests and diseases: Rare, aphids and damping off are most common

pH range: 5.5–6.5

EC/PPM: 1.0–1.8/500–900

Light hours: 14–18

Temperature Range: 55–75°F (13–24°C) Ideal: 65°F (18°C)

 

Mint

There are dozens of types of mint, but the main varieties are spearmint (Mentha spicata), peppermint (Mentha x piperita), and pennyroyal mint (Mentha pulegium). Some other varieties, like lemon mint (Monarda citriodora), are actually not mint at all. When mint is used in the kitchen, it’s usually spearmint. Mint can be grown from seed, but using cuttings or rootstock is much quicker, especially on a commercial scale. From cuttings, mint roots out and grows to maturity within a few weeks.

 

Growing Mint

Planting: Germinate from seed or start from cuttings or rootstock

Harvesting: Multiple harvests through pruning, the last of which the entire crop is harvested completely

Pests and diseases: Occasional powdery mildew

pH range: 5.5–6.5

EC/PPM: 1.6–2.6/800–1300

Light hours: 14–18

Temperature: Range: 55–75°F (13–24°C) Ideal: 70°F (21°C)

 

Oregano

Oregano is a small, bushy herb with a strong, unique flavor that’s especially pungent when the herb is fresh. The leaves are used fresh and dried in most types of cuisine, but especially Italian and French. There are three main kinds of oregano used for culinary purposes: Greek (Origanum vulgare hirtum), Mexican (Lippia graveolens, which actually isn’t oregano at all), and Italian (Origanum x majoricum). Oregano has small, rounded leaves that are fuzzy in some species—this makes it harder for them to deal with high humidity.

 

Growing Oregano

Planting: Germinating from seed works, but propagation from cuttings is best

Harvesting: Multiple harvests through pruning, the last of which the entire crop is harvested completely

Pests and diseases: Pests include thrips, whiteflies, aphids, spider mites, and leaf miners. Diseases affecting oregano plants are primarily caused by fungi.

pH range: 5.5–6.5

EC/PPM: 1.5–2.0/750–1000

Light hours: 14–18

Temperature Range: 55–80°F (13–27°C) Ideal: 70°F (21°C)

 

Parsley

Parsley is native to the Mediterranean, and it’s used worldwide both as a garnish and as a popular addition to savory dishes. Several varieties of parsley exist, from the more bitter and frilly garnish parsley to the flavorful, tender large leaf varieties. Though popular mostly as a cooking ingredient, parsley has been used in a variety of ways, from a medicinal ingredient to a symbol in ceremonies like the Seder dinner. Parsley’s tolerance of a wide temperature range and EC range make it an easy crop to grow. Large leaf varieties, like Italian flat leaf, grow abundantly in hydroponics.

 

Growing Parsley

Planting: Germinate from seed

Harvesting: Multiple harvests—it’s common to harvest parsley twice before replanting

Pests and diseases: Pests and diseases are rare, the most common pests are thrips and aphids

pH range: 5.5–6.5

EC/PPM: 1.4–2.4/700–1200

Light hours: 14–18

Temperature Range: 55–80°F (13–27°C) Ideal: 70°F (21°C)

 

Rosemary

Rosemary is a great fit for indoor farming because it can be very compact. Rosemary prefers “dry feet”—this means that you should give roots a dry period between watering. Starting rosemary from seed can be a finicky process—seeds need consistent moisture, and germination rates tend to be around 30–50%. It’s easier to propagate rosemary from cuttings, although some argue that best flavors and aromatics come from seed grown plants.

 

Growing Rosemary

Planting: Germinating from seed is very difficult, propagation from cuttings is fastest and easiest

Harvesting: Multiple harvests are common through pruning

Pests and diseases: Pests and diseases are rare, the most common are gray mold and powdery mildew when overwatered

pH range: 5.5–6.5

EC/PPM: 1.2–1.8/600–900

Light hours: 14–18

Temperature Range: 60–80°F (15–27°C) Ideal: 75°F (24°C)

 

Vegetables

 

Tomatoes

There are lots of varieties of tomatoes and most of them can be grown hydroponically. Tomatoes love light and warmth. Once the tomato plants start getting big, you’ll likely need to start pruning them so that they don’t get out of control.

 

Growing Tomatoes

Planting: Germinate from seed

Harvesting: Full harvest

Pests and diseases: Aphids, whiteflies, spider mites, fusarium, and fungal diseases

pH range: 5.5–6.0

EC/PPM: 2.0–3.5/1000–1750

Light hours: 14–18

Temperature Range: 60–90°F (15–32°C) Ideal: 75°F (24°C)

 

Cucumbers

Cucumbers thrive in hydroponics. They are a vining plant, so they will require training and sometimes a trellis to support them. They need to be pruned as well.

 

Growing Cucumbers

Planting: Germinate from seed

Harvesting: Full harvest

Pests and diseases: Aphids, whiteflies, spider mites, fusarium, and fungal diseases

pH range: 5.0–6.0

EC/PPM: 2.0–3.0/1000–1500

Light hours: 12–14

Temperature Range: 65–85°F (18–30°C) Ideal: 75°F (24°C)

 

Peppers

Peppers need lots of oxygen, so you’ll need to make sure your nutrient solution is well oxygenated. They need to be spaced 18–24 inches (45–60 cm) apart.

 

Growing Peppers

Planting: Germinate from seed

Harvesting: Full harvest 

Pests and diseases: Aphids, whiteflies, spider mites, fusarium, and fungal diseases

pH range: 5.5–6.0

EC/PPM: 2.0–2.5/1000–1250

Light hours: 14–18, most peppers grow well with 16 hours of light

Temperature Range: 65–80°F (18–27°C) Ideal: 75°F (24°C)

 

Berries

 

Strawberries

You can order strawberries from most big seed companies, with dozens of varieties available. The two main types of strawberries are ever-bearing and June-bearing—I recommend ever-bearing (or day-neutral) varieties for hydroponics. Strawberries are best grown from rootstock rather than seed. Vegetative growth (runners) tends to be much faster than sexual reproduction (seeds), so you can cut the time from planting to production by months or years by using rootstock. Strawberries are prone to pests and diseases.

 

Growing Strawberries

Planting: Germinating from seed is very difficult, growing from rootstock or propagation from cuttings is fastest and easiest

Harvesting: Multiple harvests are common throughout the growing season

Pests and diseases: Strawberries can be affected by spider mites, Pythium, and other fungal pathogens

pH range: 5.5–6.5

EC/PPM: 0.8–1.4/400–700

Light hours: 14–18

Temperature Range: 65–75°F (18–24°C) Ideal: 70°F (21°C)

 

For more great content check out the Proponics YouTube channel below!

 

Proponics on YouTube

 

 

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By Max Barnes

Max Barnes is a long-time homesteader and author. Max grows the majority of his own food year-round using a variety of different methods, including hydroponics. Hydroponic gardening plays a huge part in his homestead and self-sufficiency goals.

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