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Fall gardening in Southern California’s Mediterranean climate means long, mild autumns and an extended summer growing season. This guide is meant to help you respond to Fall gardening challenges and make the most of this time of year.
Characteristics of a Fall Garden
Fall gardening differs from spring or summer gardening in a few key ways. Days are growing shorter, and nights are starting to cool. Rather than robust and increasing growth, plants stall as shorter days provide fewer sunlight hours for photosynthesis. As the sun creeps closer to the southern horizon, longer shadows reduce sunlight even more. Cooler nights cause soil temperatures to drop, another factor stunting plant growth. Fall also ushers in the Santa Ana season, with periodic arid desert winds that suck moisture from plants and soil alike.
Despite all this, Fall is a great time to be in the garden. The oppressive heat of summer has passed, and if we’re lucky, we’ll be blessed with a little rain. Another reason to celebrate is that crops like kale and cabbage taste their best after cold weather!
Top Five Fall Gardening Tips
- Pull weeds and spent summer crops, but let a few crops go to seed (attracts beneficial insects).
- Add compost. Add more.
- Amend your soil with a complete organic fertilizer.
- Broad fork your beds to loosen compaction and allow air and moisture infiltration.
- MULCH, MULCH, MULCH! Mulching is key to moderating soil temperatures sufficient for sustaining microbial life and keeping moisture in!
Use 40% shade cloth
Shade cloth is the most important tool on our farm. We use it all year round but it is vital to our fall seed starting success. We must have 40% shade cloth to protect our baby seedlings, keep our greenhouse from getting over 100 degrees, and keep the moisture in the soil. Because we believe that shade cloth is vital to good gardening practices in Southern California, we have a specialty shade cloth made for our customers. Learn about it here: Shade Cloth
Use seed starting mix that can hold onto moisture
When you start your seeds in the heat of the summer, you need to make sure that your soil will not dry out between watering. To do this you need a seed starting mix that is heavy in peat moss and holds on to moisture. We recommend the Sungrow propagation mix that can be found online and at local farm suppliers.
Provide seedlings with proper airflow
Hot stagnant air can hinder the growth of a seedling. A small fan can make all the difference allowing seedlings to create stronger plant fibers as they move from the wind produced by the fan. The airflow also helps with insect issues by not allowing hot stagnant air around the seedling which is a prime environment to breed pests.
Avoid the Fall Effect! Plant Cool-Season Crops Early!
The Fall Effect happens as days grow shorter, the sun’s angles are lower, and evenings turn cooler — factors that cause plant growth to stall. By starting your cool-season crops while days are longer and warmer in July and August, your starts are strong and sturdy enough to plant out by the time cool weather arrives.
Seed Starting in the Fall
When starting your seeds in the Fall, keep in mind that high temperatures and low humidity mean that you need to check your seedlings often for moisture (see Tips for Germination Success).
Fall Vegetable Gardening for Zones 9 and 10
These are collectively called Cool Season Crops.
- Garlic and Onions
- Mustard greens
Fall Flowers for Zones 9 and 10
Growing flowers in your Fall garden is easy because of the cool weather and seasonal rain. Flowers such as borage, sweet peas, flax, and nasturtium easily pop up from direct seeding in cool, moist soil. Scabiosa, poppies, and cosmos are quickly started in pots and transplanted out into cool, moist soil.
- Sweet Peas
- Wildflower Mixes
Succession Planting for Continuous Harvest
If you’re growing a Fall garden in Southern California, plan to succession plant your cool-season plants so you have several rounds of the crop at different stages of growth. This allows for a continuous harvest of flowers and veggies throughout the cool season. Be mindful that as the days grow shorter and cooler, your starts will take longer to develop (see Fall Effect above).
Fall Growing in Zones 2-8
Growing in the Fall in other gardening zones in American is not as pleasurable as in Zones 9 and 10 because growing almost stops after the weather gets too cold. If you have a heated greenhouse, low tunnels, or other season-extending methods, you can grow into the cold but most vegetable crops cannot handle below freezing temperatures and some require minimum soil temperatures to fruit. Don’t worry, this isn’t a bad thing. Taking a few months off from growing will allow you to anticipate the excitement of spring gardening!
Planting in Late Summer for a Fall Harvest in Zones 2-8
If your garden gets frost, snow, or harsh winter weather, you can plant your cool-season crops in late summer for a fall harvest. To accomplish this, you will need to know the days to maturity of your crop or plant to ensure that it will mature before the first hard freeze. Knowing your first frost date is key to planting late in the season.