September in the Garden

September is a great time to catch up in the garden. Weeding, seeding, planting and dividing are all good chores for September, and in many cases it is the best time for landscape projects. Here are some suggestions to get you started.

Fall is a great time to also plant many trees and shrubs. Look for plants with healthy leaves and strong stems or trunks. Also take a tour of the Arnold Arboretum to see what those shrubs, trees and vines may look like in a few years. They have free, guided tours available as well easy self-guided gardens such as the Leventritt shrub and vine garden.

Divide and replant perennials such as Iris, Shasta Daisy (Leucanthemum), Hosta and others that have thrived in your yard. Share the surplus with friends and neighbors, also many perennials freely self-sow (Echinacea, Digitalis, Coreopsis and others), these “Babies” are easy to dig up and share as well.

Chances are if they work in your yard they will work in others.

Reseed bare spots in your lawn, September is best time of year, whether you are repairing bare patches or creating a new lawn. And remember that seed needs a little bit of water every day to germinate effectively, just enough water to moisten not drown the seeds.

Later this month, dig up your ‘tender bulbs’ Gladioli, Cannas, and Dahlias. Trim off the brown shoots and roots and store in a cool dry place for the winter.

Start repotting houseplants in preparation to bringing them back indoors. I scatter my houseplants all over my yard, under shrubs or in bare spots in the garden and typically I forget one poor plant and lose it to frost.

Thank you to everyone who has sent in ‘Questions for Cory’. I will try my best to answer those questions here.

Q. My Hydrangeas are huge this year and I want to prune them back. Is this a good time to do it?

A. Great question. And for the most part I would say yes, but there are several species of Hydrangea and not all have the same requirements, so here is a more thorough answer. Smooth Hydrangea (Hydrangea arborescens) – Big white blooms in June, this shrub blooms on new wood, so I would prune this shrub in winter or early spring. Most common cultivar is “Annabelle”. Bigleaf Hydrangea (Hydrangea macrophylla) – Probably the most common Hydrangea, white or blue blooms of mophead or lace cap form. This shrub blooms on old wood so pruning should happen right after blooming stops or you run the risk of pruning off next year’s flowers. That said, the new Endless Summer hybrids have taken out all the guesswork and worry for us. These plants bloom on new and old wood, and bloom for a full 3 months, so prune these shrubs whenever you feel like it with little consequences. Panicle Hydrangea (Hydrangea paniculata) – This shrub has made a huge comeback in standard form and with prettier cultivars. The latest blooming of the Hydrangeas, this shrub also blooms on new wood so winter or spring pruning is best. Oakleaf Hydrangea (Hydrangea quercifolia) – The easiest to tell apart due to the leaf shape (shaped like Oak leaves), this shrub blooms in June on old wood so DO NOT PRUNE now! Pruning is best done in early July right after it blooms, and the flower buds can be subject to winter kill with temps below -15’. Also, keep in mind the 1/3 rule – “Never prune off more than 1/3 of a plant in one year”.