In spring, the hyacinths can almost overpower you, but there are also some more subtle surprises - narcissi, tulips and then the stunning smell of an entire wood or field full of bluebells. And I do tend to go on ad nauseum about lilacs (posts passim).
In summer come some very heavy hitters - some of the lilies are strong enough to take your breath away and I find them rather suffocating. But sweet peas and honeysuckle? I could stand for hours and just breathe them in, to become marinated in their scent.
In autumn, it's the smell of slowly decaying vegetation and of woodsmoke.
*I spent several minutes trying to think of the smell equivalent of "glimpse" but failed. Is there a suitable word? (Cue lots of people saying "Of course there is you fool, it's ......."). It seems that the British vocabulary is well able to deal with words relating to sight and sound but less so to the senses which aren't so well developed in humans.