I'm struggling with a massive spider mite infestation on my outdoor ferns here in the Northwest UK, and I'm looking for advice. I've done some research, but a lot of the tips I find are more suited for the US, and I worry they don't apply here. I've tried Bug Clear Ultra 2, which works okay but doesn't hold up in temperatures over 25°C, which is just when those pesky mites seem to multiply like crazy. I've started cutting off infested fronds and pouring boiling water on them in bins as a last resort, but I'm not sure how effective that is overall. I'm also keeping my remaining ferns damp as much as possible since spider mites prefer dry conditions. I've ordered some Phytoseiulus Persimilis, but I've been told they might not do well in the UK climate, as I can't create the humidity they thrive in. I've heard about using a high-pressure water jet to blast them off, or trying Neem oil, but I'm wary of the impact on beneficial insects. I live in a pretty urban area, so constant watering isn't really an option. It's frustrating that there doesn't seem to be a solid solution out there. Has anyone successfully dealt with spider mites on outdoor ferns or other plants in the UK? What worked for you? Thanks in advance!
1 Answer
I've mostly dealt with spider mites indoors, so I feel your pain. I found that washing them off helps to reduce their numbers but doesn't completely eliminate them. I had good success with a systemic insecticide called Bug Clear, but it's a neonicotinoid, so I've avoided using it outdoors. I totally get your worries about the impact on wildlife and the ecosystem.
Thanks for sharing! I'm really cautious about using anything that can hurt the environment, especially with pollinators out there. It's good to know there's stuff that works, but I want to be responsible about it too. Let's hope that the predatory mites help!