I'm not familiar with the product and could not comment specifically on its use being good or bad. You could try it in a lower dosage if concerned.

Some plants take longer to wake than others. I have some that are just now starting to shine up at the tips and others have tufts of leaves at each tip.

Very often, root damage or poor root health is at play in plants slow to get going in the spring. Plants have internal chemical messengers that limit bud activity whenever the root system is unable to support what grows above the soil line. ..... not exactly a diagnosis, but a distinct possibility nonetheless.

Al

haven't used that spray myself - many of the folks on the HVH forums have plummies too - you might try the so cal hibiscus facebook page...