Posted: 16/06/2017 at 14:27
Growmore isn't really ideal, but won't do any harm. You could use proprietary feeds for Camellias, and you may need to do that if the soil isn't great, for a while anyway. Each spring you could add a slow release general fertiliser (B,F&B) and that will be sufficient if the soil's good by then. I should have asked if you have other planting nearby too - that will also deplete water and nutrients, so keep an eye on the general condition of the bed/border.
A bigger, more established plant can actually be harder to work with, but so far, it seems you're doing fine.If you're needing to water it that much, you will need to address the soil long term, because the soil is key to good growing for shrubs like Camellias. If you were in an area with high rainfall, it wouldn't matter quite so much, but if the soil isn't retaining water, it makes it difficult. I'd make sure you add some decent soil based compost (or the aforementioned well rotted manure) to the bed, rather than just compost. Leaf mould or composted bark would also be good, and you can apply that as the mulch. You can do that on a regular basis throughout the year- especially in long, dry spells. Worms will also help drag it down into the soil. It's useful to put a decent application of that down in autumn after some rainfall when the ground's moist.
Anything that improves the soil and the moisture retaining properties will be very helpful