NFT stands for Nutrient Film Technique. It was developed in England during the 1970s as a way of giving plants' roots constant access to water, nutrients and the all-important oxygen! Plants grow in a shallow 'film' of moving nutrient solution. You can grow anything from lettuce to tomatoes and cucumbers in NFT (with the right plant supports!) and the results can be very impressive indeed. What's more, there's little or no growing media involved which can seriously cut down on your regular costs as a grower.
Here are 15 great tips for growing in NFT systems (especially NFT Gro-Tanks) - all learned through blood, sweat and tears!
- Dial in your growing environment! Of course, this is something that all growers need to do, but it's especially important for those using NFT. Why so? Well, no growth media around the root zone means less insulation so less protection from extremes in temperature.
- As with all hydroponic growing applications, the temperature of your nutrient solution is crucial. Try to keep your nutrient solution at around 65°F for high levels of dissolved oxygen and optimum nutrient uptake.
- Many NFT growers start their plants in 3" rockwool starter blocks and place these directly into the grow tray through neatly cut squares in the Correx. If you go don't this route make sure that the ridges at the bottom of the cube are in line with the nutrient flow, not perpendicular to it. Otherwise your nutrient flow will be unduly impeded.
- Plants grown indoors under lights will take up water at a greater rate than they take up nutrient. Over time the EC (CF) of the solution will rise. Regularly top up your tanks with water or 50% strength nutrient solution. Keep your top up nutrient solution in a separate barrel rather than using water straight from the tap.
- Maintain the pH of your nutrient solution at around 5.8 - 6.2. Check regularly as it can rise as the plants feed. It's okay to turn your pumps off for half an hour while you adjust your nutrient solution's pH and strength.
- As a general rule, drain your nutrient solution and replace with a fresh batch every 7 to 10 days for optimum yields. Obviously bigger tanks can get away with less frequent changes whereas bigger plants prefer more regular fresh nutrients.
- Do not let any light leak into the root zone. Ensure the holes in the Correx cover are just big enough for your plants to fit through. Cover the bases of your plants to prevent green algae forming - especially important if using rockwool cubes.
- Thoroughly clean your tanks in between crops with a soap solution and rinse thoroughly.
- Use a half strength nutrient solution to start your plants off, moving to two thirds to full dosage rate (as detailed on the bottle) after the first nutrient solution change (about 7 - 10 days after planting).
- Take the opportunity to observe your plants' root growth directly by simply lifting up the Correx cover!
- Make sure you completely remove plastic wrapping from rockwool cubes or remove pots if using soil or coco. This allows the roots to access more oxygen.
- NFT is a bare rooted growing technique. When they start fruiting, all but the smallest of plants will need additional support, i.e. yoyo's or pea netting.
- Cut lengths of spreader mat long enough to allow an overhang of a few inches from the channel into the tank. No trickling water sounds!
- Don't crowd them! Plants grow incredibly fast in NFT Gro-Tanks - many growers are overwhelmed!
- Last but certainly not least-wait until roots are bursting out of your starter blocks before inserting them into your NFT system. This is absolutely crucial! Be patient - don't go transplanting at the first sign of roots. Use air pruning techniques to really make sure that the propagation media is full of roots before transplanting to your NFT system.