September To-Do List For Your Southern California Garden

Written by Susan B.

September may conjure mental images of hot spiced apple cider, earthy Autumnal colors, and crisp air, and shorter days, but Southern California isn’t like the rest of the country. We’ll continue to enjoy warm weather, and our gardens will continue to feed our stomachs with food crops and our eyes with blooming flowers, green plants, shrubs, trees, and container plants.

We’re sharing our list of critical September to-dos for your Southern California garden.

Purchase Spring and Summer Blooming Bulbs to Plant in October

Start looking for your spring and summer-blooming bulbs now. Many bulbs that start to bloom in early spring and summer will need refrigeration to simulate the cold conditions that they get while they’re in the ground over the winter in cold climates. You should purchase bulbs early enough to allow them to stay in the refrigerator for six-to-eight weeks.

Choose bulbs that are free of blemishes, tissue injuries, signs of rotting (black areas), or soft spots. Make sure your bulbs are clean and thoroughly dry before you refrigerate them.

Aerate Your Lawn

Aeration is a technique that removes soil plugs to loosen the soil under your sod. It is common for soil below the earth’s surface to become compacted from foot traffic, lawnmowers, and other activities that you and your family may engage in on your property. Soil compaction prevents your grass’s roots from absorbing water or getting necessary air circulation. St. Augustine grass is especially prone to thickening and developing thatch.

Remove Thatch from Lawn

Thatch occurs naturally on healthy grass. It consists of plant crowns that are dead or dying, plant tissues that lie between the bottom of grass blades and the soil line, and rhizome sheaths that ordinarily protect the grass. Thatch buildup looks unsightly, but more importantly, it inhibits water flow to your sod’s roots and air circulation around grass blades and under the ground’s surface.

A power rake is the most effective tool for removing thatch, but it will disturb your sod’s roots. That means that the timing of this task is critical to ensuring the recovery of your lawn. Schedule your thatch removal for around Labor Day – or as soon after that as possible.

Post-Aeration and Post Thatch-Removal Reseeding

The ideal time to reseed bare spots or holes is immediately after aerating your lawn and removing thatch. If there are areas where the grass is growing sparsely, sprinkle seed there, too.

Mow Less Often and Cut Grass Shorter

During the summer months, you let your grass grow longer because doing so protects the crowns from sunburn. It is also an effective way to promote deeper root development. Now that fall approaches, we should mow the lawn to a shorter height to force grass to focus on increasing root growth.

Mow fine-leaf fescue, Kentucky bluegrass, and perennial ryegrass to a height of 2-inches throughout the fall.

Mow tall fescue turf grasses to a height of between 2 ½-3-inches during the fall.

Although you will be mowing less frequently during the fall months, you should lessen the frequency as grass enters dormancy. Not all cultivars will go dormant.

Don’t worry about removing grass clippings. As long as their presence isn’t inhibiting air circulation or water penetration, their presence will add valuable nutrients to the soil as they decompose over time.

Feed Your Lawn Twice More During the Fall

People typically assume that nitrogen-rich fertilizers are only necessary during peak grass growing season. The most crucial fertilizer applications occur during the fall. Apply the first feeding around Labor Day or soon after that. Then apply your final feeding sometime after Halloween.

Your sod will store the nutrients from your fall feedings in its crowns, rhizomes, roots, and stolons. At the beginning of spring, as soon as ideal growing conditions return, your sod will use the stored up nutrients to jump-start new growth.

Prepare Garden Beds for Fall Planting

Although you won’t be planting most bulbs and some vegetables yet, it’s never too soon to prepare the garden beds where you plan to plant these things.

Fill your beds with 2-to-4-inches of organic soil or compost. Avoid tilling or digging the organic matter into the soil. Use a large fork instead. The fork is a more effective tool for loosening the soil to improve aeration and drainage. The looser soil will also give plant roots more room to spread.

Herbs and Vegetables to Direct Sow Now

Fine Gardening Magazine notes that now is the time to plant perennial herbs in our area. Pineapple sage is an ideal herb to grow in USDA hardiness zones 9 through 11. Rosemary thrives in USDA zones 8 – 11. Thyme grows best in zones 5 through 9, while Lemon thyme will survive as far north as zone 4 and as far south as zone 11. Orange thyme works well in zones 6 through 11.

If you want to grow beans, you can plant them now. We recommend soaking your bean seeds to soften the hard outer shell before planting. It helps them sprout faster.

Broccoli Rabe is an ideal vegetable to grow now because it is more tolerant of warm weather than regular broccoli.

Mustard greens are chock full of healthy nutrients, and if you choose to grow them, you’ll be able to get multiple harvests from a single planting. And you can continue to plant mustard through February. And you won’t have to worry about damage from wildlife because mustard tends to be wildlife resistant.

Watering

Be mindful of how and when you water. If you’re using overhead irrigation from underground sprinklers or garden hoses, plan to water as soon after sun-up as possible. When you water early in the morning, you can rest assured that all plant leaves will dry off before the sun goes down. Allowing leaves to stay wet overnight increases the risk of fungal and other diseases and/or insect infestation. You can also spray plant leaves in the early morning to remove dust, debris, or spider webs that may become nesting places for insects.

Early morning watering lessens the stress on local water supplies, where the greatest water demand typically occurs between the morning hours of 6 and 9 AM.

Give your container plants regular deep watering because this is the time of year when they dry out the fastest.

Our team of garden and landscape experts is always available to answer your questions or help you find seasonal plants, seeds, or other products. Your September gardening chores can provide you with a way to bond with your family and spend some quality time together outside.

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