Home growing: windowsill, balcony and terrace · Guides
Growing guides · Home growing: windowsill, balcony and terrace
Supplies
These supplies recur in university guides to home and small-scale hydroponics. The figures come from the same sources; fixture ratings and tent sizes are not invented.
Rule: we never invent figures. If a source has no exact value, we say so.
Circulation pumps
- NFT, recirculating DWC, ebb and flow and drip all need a pump to move the nutrient solution. UMN’s NFT parts list includes a circulation pump plus supply and drain lines. [1]
- Keep the reservoir level above the pump: UMN warns that the pump can be damaged if the level falls below the intake. Check plumbing regularly. [1]
- In NFT the solution usually flows continuously, so the circulation pump stays on (Missouri, Illinois). An ebb-and-flow pump is run on a timed flood cycle. [2][3]
Air pumps and air stones
- An air stone is a porous stone connected by tubing to an air pump; it releases tiny bubbles. UMN says it is the most common aerator in a single-container DWC, and the same devices are used in aquariums. [1]
- UNH: roots need oxygen; “overwatering” is often a lack of oxygen. In raft (DWC) systems aeration is critical, and it is done with an air pump and an air stone like those used for aquariums. [4]
- Illinois lists an air pump, air tubing and an air stone among the parts of an example homemade system. Nutrient solutions must also be aerated so roots get enough oxygen. [3]
pH and EC meters
- pH affects whether plants can use the nutrients. UMN: plants do best at pH 5.4–7; test the tap water and the solution after adding fertiliser. At home, pH paper or strips are enough (UMN mentions an inexpensive roll). [1]
- UNH: for home hydroponics a pH between 5.5 and 7.0 is fine; commercial growers fine-tune pH more tightly. [4]
- EC (electrical conductivity) gauges the overall concentration of dissolved nutrients (for example mS/cm). It does not show levels of individual nutrients. Excessively high EC can hinder water uptake and cause wilting (UMN). [1]
- Cornell’s home guide: for a home grower, pH matters more than EC, because without a suitable pH the nutrients will not be available. Handheld EC meters are available; Cornell gives a price example of US$60–100+. UNH suggests considering an EC meter once you have been growing for a while, to know when to add water or nutrients. [5][4]
- For crop-specific pH and EC targets, UMN refers readers to Oklahoma State’s Electrical Conductivity and pH Guide for Hydroponics. Those crop tables are not copied here. [1][6]
- Illinois: pH and EC must be tested and recorded regularly. [3]
Timers
- A light timer keeps the photoperiod consistent. Missouri notes that light sensors and timers can increase energy efficiency and help optimise yields. [2]
- An ebb-and-flow pump needs a timer for the 20–30 minute flood cycle (Illinois). An NFT circulation pump, by contrast, keeps the solution moving continuously, so it is not usually run on an on/off timer. [3][2]
- UNH’s 14–18 hour lamp period and Missouri Extension’s about 12–16 hours of light are in practice set with a timer. [4][2]
Enclosed growing space, tents and ventilation
- If the system is in a tightly built room or sealed chamber, UNH Extension says plants can lower the carbon dioxide in the air to about 200 parts per million in less than an hour. At that level photosynthesis effectively stops until fresh air brings in more CO₂. [4]
- UMN: ventilation is key. Avoid planting too close together, and adding a fan can help. UNH advises increasing airflow gently until the leaves are lightly fluttering — that can improve calcium uptake (lettuce tip burn, tomato blossom-end rot). [1][4]
- Missouri Extension: a general temperature range for mixed hydroponic crops is 65–75 °F (18–24 °C); plant health decreases significantly above 85 °F (29 °C). Relative humidity is often kept between 50 and 60 percent. Ventilation and air circulation are needed so humidity does not reach levels that reduce growth. [2]
- The sources do not give sizing or airflow figures for a grow tent. The same points apply to a closed cabinet, a room or a tent-like enclosure: you need fresh air, air movement, and control of heat and humidity as above. [4][1][2]
These are general guidelines. Always check the variety, seed packet or fertiliser instructions and current regulations.
Sources
- University of Minnesota Extension: Small-scale hydroponics
- University of Missouri Extension G6986: Controlled Environment Agriculture: Hydroponic Farming (July 2024)
- University of Illinois Extension (C. Hart): Home Hydroponics (PDF handout)
- University of New Hampshire Extension: Hydroponics at Home (August 2023)
- Cornell University (N. Mattson): A Guide to Home Hydroponics for Leafy Greens (2020, PDF)
- Oklahoma State University Extension: Electrical Conductivity and pH Guide for Hydroponics