Ali's Garden

MyGardenTeam member with GardenAdvice.co.uk

Avoiding Blanket Weed When Adding New Pond Plants

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Blanket Weed

One of the most common ways blanket weed (string algae) gets into a pond is through new plants from nurseries or garden centres. Even healthy-looking plants can carry small strands or spores of algae without it being obvious at first.

🪴 Why it happens

  • Plants are often grown in shared water systems
  • Blanket weed can easily spread between plants
  • Small fragments or spores are hard to spot when buying

💧 Simple way to reduce the risk

Before adding any new plants to your pond, it’s a good idea to quarantine them for a couple of weeks.

How to do it:

  • Place the plants in a bucket or container of water
  • Leave them for 2–3 weeks
  • Keep them somewhere light, but not in full scorching sun

🔍 What to look for

During this time:

  • Check for any fine green threads or slime forming
  • If blanket weed appears, remove it by hand
  • Rinse the plants thoroughly before they go into the pond

⚠️ Extra tip

  • Don’t pour the quarantine water into your pond
  • If needed, wash off the roots and replant in fresh aquatic compost

🌱 The bottom line

Quarantining plants for a couple of weeks is a simple step that can help you avoid introducing blanket weed into your pond. It’s not foolproof, but it can make a big difference—especially if you’re adding several new plants at once.