What to Do in the Garden: September

Get Ready for the Cool Season

During the hot days of September, it’s tough to imagine that the cool season is only a few weeks away!  But starting in the second half of the month it’s time to plant cool season plants and get ready for one of the busiest planting months in southern California:  October!  Here’s what to do in the garden in September:

Planning the Drought Tolerant Garden

Hopefully, you did not take out your lawn and replace it with drought tolerant plants over the summer.  Summer is a tough time to get new plants to thrive, even native plants and other low water users.  All newly planted plants require regular water while they are getting established.  If you did plant over the summer, be sure to closely monitor the new plants, test the soil moisture periodically (use a trowel to dig down a couple of inches), and water regularly.

Beginning in October and throughout the winter it is a great time to make the switch to a lower water use landscape.  Which means September is a good month to make your plant choices, review your irrigation system, and, if desired, hire a landscape designer and/or contractor.  For photos of some beautiful sample gardens, plant lists, fact sheets on landscape renovation, and watering guides for your new low water garden visit: Right Scape Resources.

Bulbs

My favorite and most exciting September garden task is to buy and start planting winter/spring flowering bulbs.  Daffodils, freesia, Dutch iris, anemone, and ranunculus are my favorites.  In September, plant the Tazetta type daffodils which include paper whites, ‘Grand Soleil d’Or’, ‘Minnow’, ‘Cheerfulness’, ‘Geranium’ and others.  You can also ‘force’ these in pebbles in pots for indoor blooms (see post on ‘Holiday Gifts from the Garden’).  The paper whites and ‘Grand Soleil d’Or’ reliably naturalize and provide blooms in late fall and winter for years and years.

Also plant in September the drought resistant bulbs from South Africa that are very well suited to our climate.  These include freesia, babiana, ixia, and watsonia which also often naturalize.  I have freesia in my garden that I planted over ten years ago that still reappear every year!

Wait until October/early November to plant non-Tazetta type daffodils, Dutch iris, anemone, and ranunculus.  Note that I have not included tulips, crocus, or hyacinths.  That’s because these need to be chilled for six to eight weeks prior to planting.  I personally can’t be bothered with this and so don’t plant them.  But if you must have tulips, put them into the refrigerator in October and chill for six to eight weeks.  See post on Fall Planted Bulbs for more tips.

Annual Flowers

The warm season annuals (like the zinnias and petunias pictured above) may still be going strong in September.  If so, leave them in and enjoy for another month or so.  If they are looking past their prime, though, remove and replace with cool season annuals such as calendula, foxglove, Iceland poppy, pansy, snapdragon, and stock.  I usually wait until the latter half of September to plant these as early September is still quite hot.  Note that these flowers are not drought tolerant and require regular watering.  I don’t plant big swaths of these any longer since I’m trying to conserve water, but save them for small planter areas or pots near the front door or pathways.  Always refresh the soil before planting by mixing in soil amendment and fertilizer in flower beds or use fresh potting soil in pots.

Perennials

September is the time to do a big clean up of the perennials in your garden.  Trim or pull off spent blooms and leaves on perennials such as daylily, shasta daisy, bergenia, acanthus, and sages.  Fall (late September through early November) is the traditional time to plant new perennials because the warm soil gets them growing right away.  They’ll slow down over the winter, but come spring they will be all settled in and ready to bloom and grow like crazy.

In the Veggie Garden

I have the same dilemma every September:  let the summer veggies keep going or pull them out and start the cool season crops.  I almost always leave the tomatoes and peppers for as long as they keep producing, because I miss them so much when they are gone!  The squash and green beans are usually looking pretty sad so out they go in favor of peas and lettuces.  Don’t feel that you have to replace everything at once.  The great thing about cool season veggies like the lettuces and root veggies, is that they can be planted in small areas.  As I remove a patch of bush beans or peppers, it’s easy to amend the soil and plant a few rows of lettuce or carrots.  September is a great time to direct sow seeds in the ground where they are to grow.  The warm soil speeds germination and plant growth.  Just be sure to keep the seed bed constantly moist until germination.  Hot days can sometimes require watering a couple times a day, especially if the Santa Ana winds are blowing.  See post on Time to Start Cool Season Seeds for more info on seed starting.