Yellowing leaves on Hibiscus
Really hoping someone can help me. I recently purchased a Hibiscus syriacus "Starburst Chiffon" from Notcutts and planted it about a month ago. Unfortunately, things have gone from bad to worse. A little before i planted it when it was still in its pot, a few of the leaves had started to yellow slightly. I put it down to not being watered enough, especially with the high temperatures we were experiencing at the time. But since i planted it, the leaves have yellowed even more and have begun dropping off. Most at the ends of the stems, but also some at the bottom too. Im watering it enough to keep the soil moist/damp and i planted it with some miracle grow compost mixed into the border soil.
Some of the younger flower buds have been yellowing and dropping off too, and the ones that do flower dont last long at all. Funnily enough, my mum also bought one of these and hers is doing worse than mine. All her leaves and buds have dropped completely. My friend also has 2 hibiscus (not the same variety) and hers are also worse off than mine and still in their original pots. Could it be just the time of year for the leaves to be falling off?
I checked the roots today and they are nice and white and healthy looking, and slowly spreading through the soil. My soil pH is around 5.8-6.0 so im wondering if this is preventing the hibiscus from obtaining the nutrients it needs? I have some lime i can apply to the soil in the hopes that this will help but thought i would get a few other opinions first. Checking the info on crocus.co.uk, it says this plant needs neutral to slightly alkaline soil. Doesn't say this on the info card that came with the plant!!
There are no bug infestations from what i can see, except for the odd slug chomping the flower buds and a small caterpillar also nibbling the flowers. No spider mite webs, aphids etc. There's 2 new leaves appearing on a couple of the stems near the top of the plant (one shown in photo) but not sure how these will develop.
Almost at my wits end with this plant but dont want to give up on it as its stunning! Would really appreciate some advice on this. Thanks