A Kratky garden is a simple way to grow a plant. There is no pump and no electricity.
Kratky Problems
Mosquitoes in Kratky containers are mainly an outdoor problem. Female mosquitoes lay their eggs on the surface of still water, and a Kratky container is a reservoir of still water by design. If there is any gap a mosquito can get through, such as around a net pot, an unused lid hole or a loose lid, it may lay eggs inside.
Indoor containers rarely have this problem, but a container on a porch, patio or balcony in warm weather should be checked.
Lift the lid and look at the water surface with a light. Larvae are easiest to see in the morning or evening.
The best defense is to stop mosquitoes reaching the water. Make sure the net pot fits the lid snugly and fill it well with clay pellets. Cover unused holes in the lid with tape or a cap. Check that the lid sits firmly on the container. For larger containers, a piece of fine mesh under the lid around the net pots adds a barrier.
Sealing the top also blocks light, which helps prevent algae. More in Algae in a Kratky Container.
Rain can wash through net pots and fill an outdoor container, which raises the water level, drowns the air roots and dilutes the nutrient. A well-fitting lid and a spot under a roof edge or awning keep both rain and mosquitoes out. If heavy rain does get in, check the water level and the roots afterward.
Larvae take some days to become adults, so acting quickly matters. Lift out the plant, keeping its roots damp, pour the solution away somewhere it will not form a puddle, rinse the container, and set it up again with fresh solution. Then seal the gaps that let the mosquito in.
Mosquito control products made for standing water are sold, but read the label carefully before using anything in a container that feeds a plant you will eat, and follow it exactly. Sealing the container is usually the simpler fix.
A Kratky container is only one source. Saucers under pots, buckets, watering cans and clogged gutters near your garden also breed mosquitoes. Empty or cover them so your plants are not sitting next to a nursery.
Heat is the other big outdoor risk. See Kratky Root Rot.
Yes, for many growers. Outdoors, plants get strong natural light, and leafy greens can do very well on a porch or balcony in spring and fall. The extra care is simply sealing the container, keeping rain out and keeping the water cool. Every other issue is on Kratky Problems.
A sealed container solves several outdoor problems at once. It keeps mosquitoes out, blocks light so algae cannot grow, and stops rain from raising the water level and drowning the air roots. Treating the water only deals with the larvae already there. Spending a few minutes on a tight lid saves checking and cleaning later.
More on choosing containers in Step 1: Pick a container.
If mosquitoes are a constant problem where you live, growing indoors on a bright windowsill avoids them almost completely. Leafy greens and herbs grow well inside with good light, and you can move containers outdoors in cooler, drier months.
After heavy rain or strong wind, lift the lid of each outdoor container. Look for larvae, check that the lid is still seated, and make sure rain has not raised the water level over the air roots. A quick look after bad weather catches most problems while they are still small.
Tip: Check outdoor containers every few days in warm weather. Larvae are easy to deal with if you find them early.
Nutrients, pH and safety guide