Some Herbs to Grow Hydroponically
Basil (Sweet)
Ocimum basilicum
A kitchen must! Basil grows well in hydroponics producing lush and flavoursome leaves:
• Temperatures of 20-24°C are ideal.
• Needs continually moist but well aerated root environment.
• Needs good light conditions, although some shade may be needed in summer.
• The ideal media are rockwool or scoria and they do well in the NFT system.
• Basic formula of 700-1100 ppm nutrient – basil needs extra magnesium (mg) make sure that the formula has 80ppm.
• The pH should be 5.5 to 6.5.
• EC requirements are low.
Planting
• Seed germinates in 4 to 7 day at 21°C in rockwool cubes or perlite.
• Plant out at 20cm spacing in early spring.
• Trellis support may be needed.
Harvest
Start harvesting before flowering starts. This also prolongs the life of the plant – just pinch out new growth often. The plant will continue to send out new growth (and flowers) until about mid-autumn when the plant should be removed.
Problems
• Vigorous roots can clog NFT channels after a while.
• Whitefly.
• Planting too early – in cooler climates this can cause plants to sit and sulk rather than grow; it also makes them more prone to insect attack. Early December is the best planting time in cooler areas.
Mint
Mentha spp.
There are several species of mint available for culinary purposes (usually Mentha x piperita or Mentha x spicata or forms thereof – some have a coarser taste than others. Those with lighter green leaves are tasty and strong – darker leaves are hairier and coarser. It all does depend on your taste too. You may need to try before you buy!
• Mint likes wet conditions and medium aeration around the roots system. It grows best in milder temperatures (15°C to 20°C). NFT has been very successful for mint.
• Basic formula of 1400-1600ppm nutrient. pH 5.5 to 6.0. It will not grow at a pH level below 4.5.
• EC requirements are high.
Planting
• Plant cuttings or divisions in late winter.
Problems
• The main problem with mint is rust – it is almost unavoidable and although difficult to control if you cut back the first growth showing signs of rust right back to media level the new growth which appears a bit later in the season tends to be rust free.
• Aphis and mites can also be a problem.
• Vigorous root system can block NFT channels. Plants should be replaced periodically.
Harvest
Like basil pinch out growing tips (use in the kitchen) as this keeps young growth occurring.
Mint is usually dormant in winter re-emerging in spring.
Parsley
Petroselinum crispum
Parsley is another stalwart in the kitchen – versatile and nutritious so well worth trying hydroponically.
• Parsley is tolerant of cold temperatures.
• It needs good aeration, but constant moisture in the root zone.
• Does not do well in NFT as roots can tend to rot; media of 30% perlite/70% coarse sand at 20cm depth produces good results.
• pH 5.5 – 6.0.
• Nutrients 560-1260ppm.
• EC requirements are low.
• Space seedlings at 10 to 20cm intervals
for optimal growth.
Problems
• Few pest and disease problems but some
insects can mark foliage occasionally.
Harvest and post-harvest
You can start harvesting parsley once they are well branched - this can take about 10 weeks from planting. Parsley is a biennial plant which means it flowers and seeds in its second year. It is best to grow it as an annual in a hydroponic system.