We are about half way through the gardening season: we stand on the continental divide with the previous 4 months or so on your right and the next 4 months on your left.  Behind you is investment in a great looking (and productive!) garden and ahead of you are some great tomatoes and apples.  Or whatever.

This midway point on the gardening calendar produces a decided change in your approach to gardening: weeds slow in growth with shorter days and cooler nights (less weeding!), grass grows better in cooler weather (this is the best time of year to start grass seed and lay sod) and the harvest of most of your fruits and veggies are ahead of you - with apologies to asparagus, raspberries and the like.  

If you have been fertilizing winter hardy plants like roses and cedar hedges this year, now is the time to stop.  It will only serve to push new growth that is at risk of winter damage as it may not harden off in time for the arrival of winter.  

If you have frost tender plants that are either in flower (petunias?) or fruit (tomatoes?) keep fertilizing them as they are heavy feeders and lets face it, when the killing frost arrives they are dead anyway.

Perennials that flowered earlier in the season should be cut down, or, at least the finished flowers should be removed.  Day lilies, hostas peonies and veronica all benefit from a non -aggressive hair cut this time of year.   

All you really need to do is remove the spent blossom to preserve energy that the plant has available for root development and, ultimately, a healthier plant next year.  Not to mention a better show of colour.