Could be that it was frost damaged or that it is not getting enough water. Gardenias love high humidity days and low temprature nights. Water often and keep soil well-fertilized
No this isn't normal. but its hard to say why it is doing this.
too much water and or fertilizer,
Never.
You may be asking about the forsythia bush. It has small, bright yellow flowers covering the branches even before the leaves have leafed out. When pruning, last year's woody stems are removed near the base of the bush, leaving new growth to produce flowers and leaves.
No. Burning Bush leaves are simple! -Anonymous Smiley :)
Either it's not getting enough water, or it doesn't have enough acid fertilizer. Lack of water of fertilizer will cause yellowing leaves.
Mid Spring in TN.
When you want your rose bush to continue to bloom, best practices dictate that you cut the spent bloom from the stalk -- cut at the junction of the bloom stalk and the larger stalk -- so that the energies of the bush can be invested in forming more buds and blooms. Pulling them off can damage the bush. A small, clean, sharp pruning shear is a better tool.
yellow bush
the leaves make photosynthesis
Overwatering, pathogens, pests, soil chemistry and sun can account for japonica leaves turning yellow. Japanese quince (Chaenomeles japonica) and glossy-leaved paper plant (Fatsia japonica) have yellow leaves when the soil pH (power of hydrogen) impedes intakes of present macro- and micro-nutrients. They also show chlorotic shoots from fungal or viral diseases, heavy droughts or floods, improper light and shade and incorrect irrigation schedules.
gardenia may be the answer you are looking for ?