(and a more proper model studied later in the case studies)
pH can be measured with colour changing papers or liquids, or by electronic meters.
pH is important because it effects nutrient absorption. Here’s a graph showing availability of nutrients in hydroponic applications at different pH levels (width of band represents availability).
Net cups are plastic cups with holes on the sides and bottom. They’re used in many hydroponic systems to suspend a plant over a nutrient solution so that the roots dangle in the solution. The hole to plastic balance is important. Holes should be:
Net cups are sold in hydroponics stores in a few standard sizes:
As a general rule, you can get away with a smaller net cup if you will have good support, and you can get away with less support if you have a bigger net cup.
Improvising net cups from household plastics like yogurt cups, pudding cups, etc:
These are commonly made from landscaping fabric, which is a fabric designed to breathe and let water through while being impenetrable to roots. They’re easy to make with a sewing machine. Using grow bags, the bag is filled with media and the whole root system lives in media, unlike with net cups where only the base is in media and the lower roots dangle in air and/or water.
Plants in grow bags benefit from air pruning, so they develop short, dense root systems and can be very well rooted even in a relatively small bag.
The three main nutrients every plant needs are NPK:
All necessary, but ideal strengths vary by plants and by phase of growth. Other micronutrients are also needed in trace amounts, but any purchased nutrient solution system will include them.
Although plants in hydroponic systems do not need to take their nutrition from soil, soil in traditional gardening serves other purposes which must be taken into account:
To serve generally these same purposes, we provide plants with a rooting medium, commonly called the media or substrate. Continue reading Hydroponics workshop: Rooting medium