The Urban Patch

If you’ve noticed tiny black flies hovering around your seedlings or landing on your soil, don’t panic – your veggie patch isn’t under siege. These little visitors are usually fungus gnats, common in moist, organic-rich soil. While harmless to adults, their larvae can nibble on roots and stunt young plants, so a little management goes a long way.

In my new garden corner which I created a few months ago, every time I lift back the canopy of nasturtium a stormcloud of fungus gnats come flying out, grrrr! Let’s dive into where to find them, and how how to control the little beasties.

🕰️ Best Time to Notice Them
Fungus gnats tend to appear during warmer months or whenever soil is kept consistently damp. Seedlings and newly potted plants are most susceptible because their delicate roots are a tasty treat for larvae.

📍 Where They Hang Out
They’re mostly found in the top 2–3 cm of soil, especially in pots, seed trays, and raised beds with rich compost or mulch. You’ll see the adults fluttering around plant bases or near windows if your garden is indoors.

🧑‍🌾 How to Manage Them

• Avoid overwatering: Let the topsoil dry out between waterings – dry soil discourages larvae from thriving.
• Good drainage: Ensure pots and beds don’t hold stagnant water.
• Sticky traps: Yellow sticky cards can catch adult gnats and give you a sense of population size.
• Beneficial helpers: Nematodes or predatory mites can target larvae if the infestation is serious.

💧 Watering & Feeding Tips
Water plants from the base where possible to keep the top layer drier. Avoid adding too much organic matter at the surface; compost or mulch should be mixed into the soil rather than piled on top.

🍽️ Harvesting While They’re Around
These flies rarely damage mature veggies, so you can continue harvesting as usual. Focus your management efforts on seedlings and young plants.

👋 Best Companion Plants
Herbs like basil and mint don’t repel gnats directly but keeping your patch aromatic can attract beneficial insects that help with overall pest control. I also like to tuck spring onion plants in various places as pests generally don’t like the smell of alliums!

💡 My Urban Patch Take
A few little black flies aren’t the end of the world – they’re part of the garden ecosystem. The key is balance: don’t panic, reduce overly damp conditions, and keep your seedlings happy and strong. With a few simple steps, you can reclaim your veggie patch without harsh chemicals and keep it thriving for summer crops.