What to do in the Garden in September

Primroses - a surprise treat blooming well
outside of its usual season this time of year.

Maintenance and Clean Up

·  Harvest winter squash when rind is hard and deep colored and the "ground spot" changes from white to a cream or gold color.

·  Pick and store winter squash; mulch carrot, parsnip, and beets for winter harvesting.

·  Protect tomatoes and/or pick green tomatoes and ripen indoors if frost threatens.

·  Stake tall flowers to keep them from blowing over in fall winds.  For some plants, an alternative is cutting back the whole plant by half in May to encourage a shorter plant.  A third option is to replace the plant with something that does its job without flopping.

The Turtlehead on the left and the hardy fuchsia in the back don't require staking.  The sad Obedient plant on the right really could use some support.

Emily Mackenzie, pictured, is a cultivar of Crocosmia that stays upright and beautiful on its own.  Lucifer, a mostly red  cultivar, is notoriously floppy and could use some support.

·  Dig, clean, and store tuberous begonias if frost threatens.

·  Harvest potatoes when the tops die down. Store them in a dark location.

·  If you do such things, fall is a good time to aerate lawns.

European Crane Fly, photo courtesy of Michigan State University

·  If you have been irrigating your lawn, stop after Labor Day to suppress European crane fly populations.  Consider the water, time, money, and pollution savings of not irrigating (and then not needing to mow as often) lawn next year.  As a compromise, the irrigation could begin as usual, but be turned off at some point through the summer. Once the lawn goes dormant, irrigation is not recommended because it requires so much water to bring it back out of dormancy. 

European Crane Fly larvae, photo courtesy of
Michigan State University

·  Recycle disease-free plant material and kitchen vegetable and fruit scraps into compost. Don't compost weeds gone to seed or diseased plants unless you are using the "hot compost" method (120 degrees to 150 degrees Fahrenheit). See this article from Washington State University for some great advice and photos.

A plastic composter is just one option.  This is
 especially good if raccoons, etc. could be a

problem for you.

Some very good things to add to your compost pile:

leaves

grass clippings that contain no pesticides

fruit and vegetable trimmings from the kitchen

coffee grounds

manure from herbivores or chickens

yard trimmings

saw dust or shavings

spoiled hay or straw

tiny twigs 

wood chips

paper with with no colored ink unless it is soy

Things that do compost but that could cause problems-

dog or cat droppings (could contain germs so don't use near edible plants)

meat (could smell bad or attract raccoons, yellow jackets, or other pest problems)

Branches, bones, compostable 'plastic' made from corn (are very very slow to compost)

Horses generate loads of manure that makes good balanced compost.  Be aware that there is sometimes grass and weed seed present.  Turning the pile thoroughly a few times will usually take care of that.

Planting/Propagation

·  Divide peonies, iris, and other herbaceous perennials.  This is easier on you and the plants if you wait until rain has thoroughly moistened the soil.  If you’d like to get started before then, irrigate very thoroughly a day or two before you dig.  You might be surprised by how long it takes to soak more than just the surface of the soil, so check with a shovel to see how far the water has penetrated.  Note:  Peonies and Alstromeria are surprisingly deep rooted.

Bearded Iris

Bearded Iris

Iris crysantha, Black Iris

·  Plant or transplant woody ornamentals or fruiting trees and shrubs. Fall planting of trees, shrubs and perennials can encourage healthy root growth over the winter and the rain saves you from having to irrigate frequently.

·  Plant daffodils, tulips, crocus, and other spring blooming bulbs. It can be beneficial to work calcium and phosphorus into the soil below the bulbs at planting time. Remember when purchasing bulbs, the size of the bulb is directly correlated to the size of the flower yet to come in spring.

·  Plant winter cover crop such as annual rye or winter peas in vegetable garden.

Pest Monitoring and Management

·  Apply parasitic nematodes to moist soil beneath rhododendrons and azaleas that show root weevil damage (notched leaves).

·  Control slugs as necessary. Least toxic management options for slugs include barriers and traps. Iron phosphate baits are the safest available for slug control. Read and follow all label directions prior to using baits, or any other chemical control.

·  Monitor trailing berries for leaf and cane spot. Treat if necessary.

·  As necessary, apply copper spray for peach and cherry trees.

·  Continue monitoring late-season soft fruits and berries for Spotted Wing Drosophila (SWD).  If SWD are present, use an integrated and least toxic approach to manage the pests.  Learn how to monitor for SWD flies and larval infestations in fruit by clicking this link. 

Late blight, photo courtesy of
PNW Handbook

·  If late blight occurs on tomatoes or potatoes, See thislink.   We recommend following controls listed under ‘Management in Organic Production’ (only minimal use of copper sprays and Serenade if you really need to spray) rather than ‘Chemical Controls’. 

Bitter pit, photo courtesy of
PNW Handbook

·  Watch for bitter pit on apples and pears.  See this link for details on the condition and how to ameliorate it.  
We highly recommend the Pacific Northwest Handbooks for researching and learning how to treat insect and disease problems.  See this link.

Houseplants and Indoor Gardening

·  Clean houseplants, check for insects, and repot and fertilize if necessary; then bring them indoors before frost if they have been summering out of doors.