September in the Garden

Perhaps you have noticed the days are getting shorter? A sure sign that summer is winding down and fall is around the corner. I think of the garden year not from January-December, but from autumn to autumn, since so much of our garden creation and re-creation happens in the fall. The first half of September is preparation, and the second half is when the action really begins.

Planting: The vegetable garden transitions from warm to cool season, so there will be some of each in the beds this month. My tomatoes must stay in longer because they are setting better fruit now than they did in summer. But I’m cleaning out the rest of my old tired, buggy squash and melon plants and will let the beds rest a few weeks, before planting seedlings of broccoli, cabbage, and cauliflower. You can also plant seeds of carrot, lettuce, parsley, green onions, peas, radish, chard and other greens, turnips, seed potatoes and flowers like calendula, alyssum, snapdragon and poppies. You can also start planting trees and perennials or wait another month.


Above: Vegetable seedlings we started in August will be ready to transplant in a few weeks. They still need a little time to grow and then harden off out of the greenhouse.

Maintaining: Pay attention to anything you plant this month. In the vegetable garden, aphids and white fly may still be active, and earwigs will be emerging from summer siesta. Continue with ant baits in edible and ornamental beds. Trees and perennials you plant need to be monitored closely if the weather remains hot all month.

As in the vegetable garden, September is also clean up month in the ornamental beds. Trim and prune shrubs, evergreen trees, and flowers. Trim and divide bulbs, corms and tubers if you haven’t yet. They need to be replanted by Thanksgiving. Dispose of any remaining fruit and nuts on trees or on the ground. Aerate cool season lawns. Keep plants free of dust to discourage spider mites.


Above:Towards the end of the month, I’ll give these spring blooming native sage shrubs a good trim.

Fertilize cool season lawns, following package instructions closely. Err on the side of too little instead of too much.

Apply ¼ cup each of Epsom salts and Ironite to each of your rose bushes around the base and top off with compost.

You can apply pre-emergent herbicide for cool-season weeds starting this month or wait until the rain will water it in for you. Watch for annual blue grass, brome (foxtail) and other non-native weedy grasses to emerge and use a hoe or hand pull to reduce their numbers.

In addition to the roses, compost can be top-dressed in all beds, and go ahead and add mulch beginning this month. Check soil moisture with a monitor or your hand to adjust watering as the weather changes. Heat waves may occur, so be ready to pre-irrigate as needed to keep plants stress-free.

Conserving: While you’re trimming and slashing your way through the garden, keep an eye out for wildlife you want to conserve. Lizards, spiders, toads and moths are still active and all of them have a place in the well-managed garden. Keep the bird baths full. Trim flowers off tropical non-native milkweeds, or better yet, replace with a species that is native to your area. Consider replacing a few more high-water-use ornamental plants with those that thrive on less water. Consider creating a seasonal garden, including some plants that are dormant in summer. Is that a new idea to you? Growing to understand and work with our particular climate is part of our role as gardeners of a true California garden. It’s a lot easier than fighting against weather, lack of water and wildlife. Have a great September!

Peyton