Many thanks for your recent enquiry concerning the non-flowering camellia you are trying to nurture back into bloom.
From your description below, it seems that it has been under attack from spider mite and camellias are also susceptible to the attentions of scale insects and mealybug with the roots a delicacy for vine weevil larvae – so there are a few pests we need to potentially take care of first!
Glasshouse red spider mites are not actually red (as you say) for the majority of the summer but instead are yellow/green with two darker markings on their back, giving rise to one of their other names of two spotted mite. Once the webbing these creatures produce to protect themselves and move around can be seen, they have reached infestation proportions and you will need to spray them to regain control.
A Natural Power Bug Spray will also take care of mealybug but due to the protective waxy covering this pest enjoys, you’ll need to spray twice in a week to firstly break down the coating and secondly to kill the bug.
Scale insects shouldn’t affect the ability of the camellia to produce buds and flower but they can cause the plant to suffer. It’s likely that soft scale are to blame and if these are present, it’s the best time to control them. Spraying now will target the newly hatched nymphs which are vulnerable before they develop their protective shell.
Moving on, I’d certainly suggest you remove the camellia from its long term home and replace the compost. Camellias are acid loving plants so an ericaceous compost should be used and you could also start to feed them with a potassium rich fertiliser later in the year to help bud and flower development in the winter and spring, which you can incorporate into regular watering. Moving forward, it’s good practice to replace the compost every couple of years to make sure the plant is as happy as possible.
Re-potting will also give you the opportunity to examine the roots for evidence of vine weevil larvae, which you will need to treat, we supply nematodes, supply, which can be applied in September and again in March for the maximum effect.
Hopefully re-potting, feeding, regular watering and dealing with any pests present should see an upturn in the fortunes of the plant but if you’ve any further questions or queries, please don’t hesitate to ask.
Many thanks once again for your enquiry and the best of luck with your garden this year.