***This list is courtesy of Mark Cullen 🙂
Peonies. September is ‘peony splitting’ month. If you have one that is too big for the space that it is in or if you just want to move it, now is the time. If you divide it, do so with a sharp, serrated kitchen knife. Plant peonies no more than 10 cm (4 inches) below the surface of the soil and in a bright, sunny place in the garden.
Seed and sod. If your lawn looks amazing right now skip this part. If it has some brown spots, weak areas or is tired looking, now is the best time to thicken it by over-seeding with lawn seed. First spread 3 to 5 cm of lawn soil over the area to be seeded, rake smooth, broadcast the seed by hand, rake again and step on it to firm the soil/seed into contact. Water well.
Fertilize early in September with the regular formula and apply the fall formula in late October through November to winterize your lawn.
Prune. Cut back the flowering shrubs that bloomed in July and August. Remove spent blossoms on Butterfly Bush and Rose of Sharon to encourage more blossoms later on in the season. Unruly evergreens can also be pruned back this time of year.
Harvest. Tomato plants are producing like they have never before this year. Mind you, they ripened a little late but that was due to the cool evening temperatures. Now that they are coming along, pick every day to keep them from rotting on the vine or splitting after a heavy rain. Harvest early ripening apples and pears.
Plant. As your annual flowers begin to wane, now is a good time to plant fall flowering mums, New England asters, sedum and ornamental grasses. No reason to put up with mediocre performance in your garden when you can have a show stopper. All winter-hardy nursery stock can also be planted now. You may have better luck with fall planted trees, evergreens and the like than I do come spring.
Reward yourself. If you have kids that are heading off to school be sure to spend some time in your garden alone over the next few weeks. Take the time to enjoy the quiet and solitude. Take pictures – come mid winter you will be glad that you did! And observe the many birds that visit your garden this time of year. Note that many are ‘new’ as they are passing through right now on their way to their southern winter home. Enjoy.
Holland Bulbs. Tulips, daffodils, hyacinths and the like are in the stores now. I know that it feels early, but the Dutch harvest was a good one and the selection of these bulbs is best in September. I urge you to buy yours early to get the pick of the crop: by October all of the hard to find and unusual varieties are gone.
Deadhead roses. Remove the finished blossoms to encourage more.
Apply dormant nematodes to your lawn to control common grubs. Available at participating Home stores and many independent garden centres.
Wisteria. Cut back the ‘whippy’ growth that occurred this summer to encourage flowers next spring.
Raspberries. Prune out the canes on which fruit occurred this summer (July bearing). Allow the new growth room to produce a crop next season.