Pest Control Calendar

Plant Pest Control Planning


Most biological pest controls will only work if the pest is present, the pest is their source of food.  This guide focusses on growing outside and in greenhouses.  For houseplants pests may be present all year, they will grow in numbers when it is warm and there is more natural light so be extra vigilant in summer months.

Plant pest control calendar


  • Check over your notes from last year, what pests did you see and when did you start to see them?
  • Set yourself reminders to check for these pests earlier this year




  • Check for and treat fungus gnats (Sciarid Fly) with nematodes and sticky traps
  • Check for aphids (greenfly/blackfly), spray with Horticultural Soap everyday and order some live predators


  • Be vigilant, thrips and spider mite can spread quickly and cause serious damage
  • Look out for adult vine weevils, use vine weevil traps and keep up the nematode treatments
  • Treat for whitefly when you see them with the parasitic wasp Encarsia Formosa


  • June is peak pest season, you may feel under siege, it’s not just you!  Most plants will be able to withstand a bit of nibbling.
  • Aphid controls are a must, lacewing and ladybird larvae are great
  • Keep ant numbers down with nematodes, ants will farm aphids and stop the natural predators from getting to them


  • In hot weather spider mites can grow in numbers incredibly quickly, keep plants cool and damp and introduce Phytoseiulus predatory mites
  • Vine weevils will be busy laying eggs and nibbling the leaves of shrubs, replace traps and keep up nematode treatments


  • If you’ve been using nematodes, you may not have seen many slugs this year.  Now and into the autumn is key for treating them, they are laying eggs and the population is swelling
  • Thrips will remain a problem as they come across from farmland


  • Have you been noting down any pest issues you have had?  Now is a good time to review your notes (or make them!) so that you can be prepared for next year
  • Treat lawns for chafer grubs and leatherjackets, these may also be present on areas that were previously grass


  • Get your last slug and vine weevil treatments down
  • If you have had aphids, spider mites or thrips this year you need to have a really good clean up, these pests all overwinter and will come back in bigger numbers next year


  • Clean pots, trays and other tools thoroughly 
  • Disinfect greenhouses and other structures


  • If starting things off for next year, set up sticky traps 
  • Treat fungus gnats (Sciarid Fly) with nematodes

If you need help with a plant pest and you can't find the answer email