Your forsythia shrub now is probably a fountain of gold. Or maybe it isn’t. Blooming season is when a less-than-forthcoming forsythia makes itself very plain. Wonder why?
Forsythias always make this year’s flower buds last year. And most of the time when they don’t bloom it’s for two reasons related to pruning. Yours might not be blooming because:
A) if it has a bald spot, like the one above, you pruned your forsythia too late in the season, after the flower buds had formed. By removing the new season’s branches in let’s say summer or fall, you also removed the flowers for the following spring. The time to prune your forsythia is either during flowering (to enjoy those golden boughs indoors) or immediately after flowering.
Cut the branches back much lower than the height you want the shrub to be. The new growth will proceed from the top couple of buds, in a Y pattern, and if you cut the branch too high, then the two new stems shoot outward rather than upward. That’s how older specimens end up with that higgledy piggledy look.
B) or, if it’s a raggedy old shrub like the one to the right here, your forsythia might be badly in need of pruning to rejuvenate it. If the base of the shrub is congested with stems, cut one-third of the oldest, thickest branches to the ground, and do this for each of the next two years. This will open up the shrub to more new, vigorous flowering branches. If possible, allow the forsythia to have an open, vase shape. It really is the most attractive form.
However, the older varieties of forsythia tend to be large, huge in some cases, and people tend to lop them back so they don’t feel they’re being invaded by triffids. If your shrub is too large, find it a suitable home elsewhere, where it has room to roost. In its place, select one of the newer compact cultivars such as Forsythia ‘Happy Centennial’ which remains about 3 feet (1 metre) tall, and spreads a little wider.
Forsythias bloom best in full sun, though will take part shade. However, if yours is deeply shaded, it will not be as flamboyant as it would be in a sunnier position.
A last reason for non-blooming is when they’ve gone through a particularly harsh winter, which damages the flower buds. That didn’t happen in Toronto’s winter of 2009/10, but when it does you can tell by the fact that only the lower branches (the ones covered with snow) are blooming.
So go for the gold, and treat your forsythia the way he likes to be treated.