Use a clear jar with a sleeve that slides off. Students lift the sleeve to look at the roots and the falling water level, then slide it back. Algae needs steady light, so brief looks don’t cause a problem. Why Not Just Use a Clear Jar? Light reaching the...
Loose-leaf lettuce. It germinates quickly, grows well in a single jar, doesn’t need much space, and gives children something to harvest within a school term. Basil is a good second choice in a warm, bright room. Why Lettuce Fast, visible growth that keeps...
Use a liquid pH test kit or pH test strips. Both work without power: you compare a color against a chart. Liquid kits made for hydroponics are usually easier to read in the range that matters for growing. Liquid Test Kits Put a small sample of solution in the test...
Yes. Rainwater collected from a clean surface and stored covered works well for Kratky. It’s naturally low in minerals, so your nutrients make up most of what’s in the solution. You still need to add a complete hydroponic nutrient. Why Rainwater Works Tap...
Yes. An unheated greenhouse can drop below freezing on clear winter nights, and nutrient solution freezes at close to the same temperature as water. Frozen solution damages roots and can crack containers. Why Greenhouses Still Freeze A greenhouse traps heat during the...
Ventilate the greenhouse, shade it, and keep the containers themselves out of the sun. Warm nutrient solution holds less oxygen and encourages root rot, and a still container in a hot greenhouse warms up quickly. Ventilate Open vents and doors early on warm days,...
No. Give your plants a dark period every day. Leafy greens and herbs grow well with long days, but running lights around the clock uses more power and can stress some plants without a worthwhile gain. Why Plants Need Darkness Plants do part of their growing and...
Start at the height your light’s manufacturer recommends for leafy greens, then adjust based on how the plants look. Lights differ so much in power that there’s no single right distance. Signs the Light Is Too Far Away Long, thin, pale stems Plants leaning...
Close every opening to the water. Mosquitoes lay eggs on standing water, and a Kratky container is standing water, so snug net cups, sealed lids and fine mesh over any gaps stop them breeding there. Where They Get In Gaps between the net cup and the lid Unused holes...
