September in the Garden
September can be a tricky month with quirky weather. Our summer has been hot, with more predicted. Usually we have a dry Santa Ana weather condition or two, so pay extra attention to your yard when the weather gets hot and dry. By the end of the month, temperatures should be stabilizing and we can be pretty sure that the weather won’t be so hot as we head into our fall. ( Famous last words! ) Bottom line: water!
Mulching is the key to keeping plants happy during the hot months. Mulching to about 3-4 inches in-depth, keeping away from the trunks of your plants, keeps water evaporation down to a minimum, helps insulate to roots, keeps soil temperature more constant, and discourages weed growth.
Annual herbs prefer a composted mulch while perennial herbs like a bark mulch.
Clean out garden debris, dead flowers and leaves to keep the insect populations in check.
Probably my biggest job in September is the job of preparing the soil for the planting I will be doing during the next two months. Soil prep is so important to the health of our plantings. It’s worth taking the extra time to prep for the payoff you’ll get down the road. Once you’ve cleaned out and amended, let the bed rest for a couple of weeks. Turn the soil, water deeply, and wait a few weeks for weeds to germinate. Weed out these opportunists! Think: Turn…Water…Wait…Weed. Add a 3 – 4 inch layer of organic material: home-made compost, purchased compost or planting mix. Add an all-purpose food and turn in well.
Camellias are starting to bud out now. Thin the buds on your camellia plants this month and next to promote a better bloom next winter. Thin out a combination of smaller and larger buds so your upcoming bloom will span a longer period.
This month and next are my big pruning months of the year. It’s the time to really clean out by heavy pruning drought tolerant plants as they finish out their last few months of spectacular growth. Clearing them out now will give them a good head start for winter and the new growth will be so much more vigorous.
There is conflicting information about when to trim back red fountain grass, i.e. now or in December, but I compromised between the two times last year and got good results. In September I gathered up the center of the plant with string and trimmed away everything hanging low on the sidewalk. The center of the plant still looks vibrant and lasts for a few more months. In December I mowed the grasses all the way down as far as I could (about 3 inches off the ground). Within days new growth is popping up and the plants start over again for the new year.
Force your summer crops by pinching off new blossoms on melon, squash, eggplant, and tomatoes. This will force plants to ripen fruit already on the plant.
Fall is a great time to plant just about everything, except tropical plants. If you are planting natives and drought tolerant plants, wait until the second half of the month.
Bulbs are starting to appear at local nurseries so get your favorites while they are in stock. These wonderful drought-resistant bulbs and corms from South Africa including freesia, babiana, crocosmia, sparaxis, tritonia, watsonia and ixia. Plant bearded iris rhizomes in areas that get at least a half-day sun. Other Spring-flowering bulbs such as daffodils are planted later.
It’s time to get sweet pea seeds started for a winter bloom. Look for early blooming varieties in local nurseries. Spring and Summer flowering types won’t bloom until the days are more than 12 hours long. Soak the seeds over night to soften the outside layer.
It’s also time to get your winter veggie seeds planted. Start small batches and then every three weeks, start new batches, so you have a staggered harvest schedule down the road. Also, we know the hot weather is coming. Stagger your plantings so if your first batch or two of plantings get fried, all is not lost. Forge on…..
Spring and summer-blooming perennials can be dug up and divided now through early fall. Use the extras to fill in bare spots in your yard, or share with your neighbors and gardening friends. Keep them watered regularly for the next few months while they are getting established.
A Guide to Planting:
Flowers From Seed – these can be planted any time this month: African daisy, Alyssum, Bachelor button, Bells of Ireland, Calendula, California poppy, Candytuft, Canterbury bell, Carnation, Chrysanthemum, Cineraria, Clarkia, Columbine, Delphinium, Forget-me-not, Foxglove, Gerbera daisy, Godetia, Hollyhock, Iceland poppy, Larkspur, Linum, Mignonette, Nicotiana, Pansy, Phlox, Scabiosa, Shasta daisy, Snapdragon, Stock, Sweet pea, Sweet William, Verbena, Viola, Wildflowers.
Flowers From Bedding Plants: African daisy, Alyssum, Calendula, English daisy, English primroses, Gerbera daisy, Iceland poppy , Pansy, Penstemon, Primula malacoides, Snapdragon, Stock, Viola . Note: Better to wait until the weather cools toward the end of the month to set out transplants for these plants.
Vegetables: Beets, Broccoli, Brussels sprouts, Cabbage, Carrots, Cauliflower, Celery, Kohlrabi, Lettuce, Oriental greens, Peas, Potatoes, Radishes, Spinach, Sugar snap peas, Turnips.
Don’t water your Christmas cactus for the next month and a half to help set buds on your plant. It’s not an exact science but hopefully this will have your plant in bloom for the holidays.
When the weather gets hot and dry, it is important to keep your citrus evenly watered or the result can be split fruit.
Always make sure to water first before fertilizing, preferably the day before, especially during hot weather, or you will risk burning the plants’ roots.
This is the last time you will fertilize your citrus until the beginning of next year. Use a formula specifically for citrus to make sure your trees are getting the trace minerals they need, too.
My naturalized bulbs will start to peek through the dirt any day now, so I’ll spread some bone meal out there to fortify them a bit.
Roses can be fed one last time this year with a half strength dose of fertilizer. Add two tablespoons of Epsom Salts to each plant for a dose of magnesium.
Apply a half-dose of fertilizer to your bedding plants. We don’t want to encourage a huge flush of growth as we go into fall, but we do want to make sure the plants are getting the nutrients they need to stay healthy and fight off pests.
As the buds set on your azaleas and camellias, feed them with fertilizer tailored to their needs.
To get blue flowers on your hydrangeas keep the soil acidic at a pH @ 4.5 – 5.0. Fertilize with aluminum sulfate using 1 tablespoon per foot of plant height or 1/4 teaspoon per potted plant. Mix with water and apply it several times in the fall and spring beginning in September. This must be started before they start developing buds or it’s too late for this season.
If you are ready to promote bloom spikes on your cymbidiums, it’s time to switch to a lower nitrogen fertilizer. Higher phosphorous and potassium will encourage bloom spikes such as 15-30-15 or 10-30-10. Personally, I usually wait a few more months to change fertilizers so I can delay my blooms, in hope that blooming happens for the Coronado Flower Show in April, but the plants start shooting up bloom spikes earlier than I plan and the timing never works out! This year I think I’ll switch fertilizers sooner to promote better blooms for me rather than trying to time blooms for showtime.
Pest & Disease Control:
If you see little white moths flying around your cabbage, brussels sprouts, and broccoli, watch for their caterpillars and spray with Bacillus thuringiensus.
If you are seeing white fly flitting around your garden, locate the source, then blast the plants with a jet spray to wipe out the little nasties. Natural predators are ladybugs or lacewings, but if the white fly is out of control natural predators won’t be able to keep up. I’m washing my citrus trees twice a week in the morning with a cup of coffee in one hand, and the hose in the other.
Sunscreen, a hat and lots of hydration!!! Many gardeners follow the unwritten rule of gardening: Put on a wide-brimmed hat and some old clothes and, with a hoe in one hand and a cold drink in the other, show your husband where to dig while you read a great garden magazine!
Credit where credit is due: This monthly garden chores compilation comes from a lot of resources, past and present, including: Sunset Magazine, Union-Tribune, San Diego Floral Association, San Diego Horticulture Society, San Diego Home & Garden, Anderson’s La Costa Nursery, miscellaneous tidbits found on the web, in the library, from fellow gardeners, and personal experience in the garden.