Total-control Indoor Gardening with Modern Hydrop

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I have little $10 digital humidity—gauge/thermometers all over the place. Frequent water baths, transpiration, and a steaming kettle on the wood stove in winter keep the relative humidity at a comfortable (for people and plants) 40% or higher in winter. Relative humidity is the percentage of air's potential carrying capacity at a given temperature; dew point is the percentage at which water vapor precipitates out of the air as fog or rain. If you boil too much water into the air, you'll exceed the dew point, and water droplets will accumulate on every cool surface and encourage the growth of mildew everywhere—bad news for hydroponic plantings.

Plants suffer as much as humans from excessive heat. In northern New England, we seldom have overheating problems, but a large window fan over the plants will generate a sufficient, cooling breeze during a brief heat wave.

Where you have greatest latitude for active growth management is in the formulation and supply of the water used to nourish your plants. In soil, plant roots are bathed in an irregular downward trickle of rainwater that dissolves plant nutrients out of natural organic soil or brings down chemical fertilizers ... and carries off the mineral salts that are left over when plants have extracted what they need. Lacking adequate drainages in waterlogged garden soil, a planting pot lacking a drainage hole, or ultimately in Utah's Great Salt Lake or the Holy Land's Dead Sea-the salts can build up to the point that the water can float an egg ... and kill most plant and animal life.

In "active" hydroponics, plant roots receive periodic drenchings in warm aerated nutrient solution that is pumped to them and allowed to drain off. The solution is tested for pH and nutrient strength and is reinforced periodically with nutrient. Before salts accumulate to harmful levels, old solution is replaced-typically after one to two weeks' use.

Wetted periods depend on the growing medium, plant type, and the water flow system. Systems include: passive self-watering planters; open-mesh-bottomed pots that are given a twice or three-times-a-day hand-poured drench- and-drain soaking; shallow water tables where pots sit in a periodic pool of nutrient; scores of pots in an array connected by water supply and drainage tubing to a controller; and sophisticated nutrient film technique (NFT) systems, where there is no rooting medium, but roots are maintained in an air-permeable film of nutrient, gotten from a mist created when solution is pumped rapidly beneath them in long growing channels.

System mechanics are fun to design and can get as complicated as your tinkering aptitude wants to make them. But home-grade systems are more for operator convenience (and entertainment, dare I say) than growing advantage. More important than the mechanics is the makeup and management of the nutrient solution. First consideration is the water, the basis of all life.

H20

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