I'm performing a research to see if artificial light from street lamps affects the growth and shedding of plant leaves.

In order for me to discuss my results I have to know if these plants are long-day or short-day plants.

The way I understand it from having researched, my plants are long-day plants as they are blooming in the spring when there is more than ~6hrs of sun per day.

But is bloom time only when actual flowers bloom or can it be when the leaves sprout? The way I see it it's when the plants comes out of dormancy, whether that be in the spring or in the fall. But trees such as a few varieties of Oak defy this as their flowers grow prior to their leaves. It really confuses me as to what can be called long-day plant.

The plants in question are:

Species 1. Lilac - Syringa vulgaris.

s.2. Cherry - Prunus avium

s.3. Maple - Crimson King

s.4. Spiraea

s.6 Sycamore

s.8 London Plane

s.10 Hawthorn - Crataegus sp.

s.12 Willow - Salix sp.