Have you ever bought a fresh bag of potting soil and discovered a swarm of fungus gnats when you opened it? Unfortunately, this is not uncommon and can hardly be avoided. Because potting soil magically attracts pests. Care errors can also lead to an infestation later in cultivation. Read how to get around this here.
How can you avoid fungus gnats in potting soil?
To prevent fungus gnats in potting soil, the soil should be stored dry and cool. Seal opened bags airtight. Place plants on a saucer to be watered on rather than directly on the substrate. Use perlite or quartz sand as an alternative.
No need to worry
Certainly a plant swarmed by fungus gnats is not a pretty sight. The plant itself hardly suffers from an infestation, because
- only the larvae feed on the leaves.
- These are fully grown after a few days.
- Flies only eat organic plant remains.
- Only weakened plants or young shoots are at risk.
This means that you only have to fight fungus gnats if there is a very heavy infestation.
Identifying fungus gnats
To detect fungus gnats on your plant, you can use two methods:
- Flooding the substrate
- Apply an organic paper strip
Flooding the pot
When there is waterlogging, the fungus gnats fly to the surface. Find out beforehand whether your plant can tolerate the procedure.
Organic paper strip
Since fungus gnats feed on organic plant remains, they will also nibble on the paper strip.
Pay attention to the care of the potting soil
Sad gnats love moist potting soil. It is therefore better to place your plant on a saucer that you water instead of the substrate. You should always store purchased potting soil in a dry and cool place. Opened bags must be sealed airtight.
Tip
If you're just not having any luck buying your potting soil, perlite (€12.00 at Amazon) is a sensible alternative. There is no risk of fungus gnats being in the substrate. If you don't want to do without potting soil because hydroponics seems too complicated, sprinkle some quartz sand on the substrate. This prevents the females from laying eggs.
