What to Plant in Santa Cruz & the Bay Area in September

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A bowl of ripe tomatoes on the counter and a packet of lettuce seed beside it: September makes room for both. In Santa Cruz County, summer crops may still be producing while the next season needs a place in the garden. You do not have to clear every bed at once.

Use openings for cool-season vegetables, protect tender starts during hot spells, and decide which summer plants are still earning their space. The local UC Master Gardeners' September guidance recommends fall greens and brassicas while reminding gardeners to delay planting or shade seedlings during a heat wave.

Let the weather set the pace

September does not arrive with one set of temperatures across the county. Check the forecast and the actual bed before deciding what to plant:

Sunny mountain ridges: exposed beds can remain hot and dry. Tender starts may need temporary afternoon shade.

Redwood-shaded gardens: shade changes both heat and available light. A cooler bed is not automatically a productive vegetable bed.

Inland valleys and hills: compare afternoon heat with nighttime conditions. Nearby slopes and low spots can behave differently.

Coastal gardens: marine influence can moderate heat, but hot spells still reach the coast.

Watsonville and Pajaro Valley: exposure and marine influence vary. Use your own garden's conditions rather than assuming the whole area is uniformly warm.

Look at the plants too. A healthy tomato carrying ripening fruit offers a different choice from a tired vine occupying the only bed available for broccoli. Keep the harvest you value, with the next crop in mind.

What to sow in an open patch

Cool-Season Greens

Lettuce: try a variety sold for heat tolerance, such as Jericho, Muir or Nevada, when conditions are still warm. Shade the seedbed as needed and watch its moisture.

Arugula: sow a small patch for peppery leaves. Heat can bring flowering sooner, so a modest sowing is easier to use than a whole bed.

Spinach: wait for cooler conditions if the bed is hot. Bloomsdale Long Standing is one option, but a variety name does not remove spinach's preference for cool weather.

Mustard greens: Red Giant and mizuna offer different flavors and leaf shapes. Young leaves make a useful small harvest while you learn the variety.

Chard: Bright Lights and Fordhook Giant are options for greens that can carry on through changing conditions.

Mizuna: this mild mustard green is useful when you want something gentler than a strongly flavored mustard.

Asian greens: bok choy and tatsoi fit the cool-season garden. Hold off during intense heat rather than planting simply because it is September.

Mâche (corn salad): save this for genuinely cooler conditions. There is no need to force every green into the bed on the same day.

Root Vegetables

Radishes: Cherry Belle and French Breakfast are small types to try. Use the packet's maturity estimate as a guide, then check the roots; heat and growing conditions affect quality and timing.

Turnips: Hakurei and Tokyo Cross are options for tender roots. Make space for thinning rather than leaving every seedling crowded together.

Beets: Detroit Dark Red and Chioggia offer familiar red and ringed roots. Keep the seed zone moist while they emerge.

Carrots: Nantes and Danvers types are options for a fall sowing. The surface must stay moist through their slower germination, so start with a row you can check regularly.

Legumes

Peas: sow when heat eases and the bed has enough sun. Sugar snaps and snow peas need support. Harvest timing depends on variety and conditions; an autumn sowing is not limited to a guaranteed spring harvest.

Fava beans: plan an autumn sowing, often later in the season as conditions cool. They can also be grown as cover crops, with a different cutting schedule from beans grown for food.

Herbs

Cilantro: direct-sow for the cooler season. It can still bolt during heat, so smaller repeat sowings are useful.

Dill: Quick to germinate and produce. Let some go to seed for self-sowing.

Parsley: Both flat-leaf and curly establish well. Slow to germinate, so be patient.

Cover Crops

If a bed will rest from vegetables, consider an autumn cover crop once you can provide establishment moisture:

Fava beans: an option for living cover or an edible crop. Cutting at flowering for green manure means giving up the later bean harvest.

Crimson clover: Beautiful red flowers in spring, fixes nitrogen, attracts pollinators. For more on beneficial plant combinations, see our companion planting guide.

Winter vetch: a legume often used in mixtures. Choose a suitable species and plan how you will cut it before unwanted seed forms.

Give transplants a gentle landing

Brassicas from summer starts

Broccoli: September transplants are a useful fall-garden choice. Check variety timing, leave room for mature plants and avoid exposing new starts to a heat wave.

Cauliflower: plant suitable transplants during a mild spell. Heading time depends on variety and conditions rather than a countywide cutoff.

Cabbage: choose the variety and maturity that fit the harvest you want. A small start will eventually need considerably more space.

Kale: Lacinato and Red Russian are options for fall planting and repeated leaf harvests.

Collards: another leafy brassica to consider. Even robust crops need care while their transplanted roots establish.

Other Transplants

Lettuce: starts give you a head start where seed germination has been difficult. Protect them during hot afternoons.

Onions: match the type and planting material to the local season. Bunching onions and bulbing onions have different goals, so check a local planting guide before buying sets.

Strawberries: autumn planting may fit some varieties and nursery stock. Confirm the recommended planting window for the plants offered; do not assume bare-root plants are available or appropriate in September.

Keep picking what is ready

The harvest depends on what you planted and how the season has treated it. Walk the garden before deciding what needs replacing:

Tomatoes: keep picking ripe fruit on healthy plants. A productive vine can stay while you prepare another part of the garden.

Peppers: harvest at the stage you prefer, or leave suitable fruit to color while conditions allow.

Eggplant: Still producing in warm areas.

Summer squash and zucchini: keep harvesting productive plants and watch for powdery mildew.

Beans: check late plantings frequently so pods do not become overmature.

Cucumbers: May be winding down but still productive.

Melons: Late varieties are ripening.

Early fall greens: take usable leaves from established lettuce, arugula or kale instead of waiting for a single large harvest.

Apples and pears: Tree fruit season continues.

A short September work list

Make a space decision. Identify the summer plants worth keeping and one opening for the next crop.

Sow a manageable patch of greens or roots when conditions suit them.

Plant brassica starts during a mild spell and water them in.

Check strawberry timing for the specific plants you intend to buy.

Be cautious with another summer crop. A late bean or squash planting is a gamble on remaining warmth and daylight, not a dependable second season.

Check irrigation. Match watering to the root zone and weather rather than reducing it automatically in September.

Protect tender starts from intense afternoon sun while they establish.

Keep the next crop in view. Productive summer plants can stay, but do not let an exhausted plant use all the space needed for fall.

Save suitable seed from healthy plants if you want to try it next year. Open-pollinated tomatoes and peppers are useful starting points.

Plan garlic. Check seed-garlic availability and the local fall planting window.

Adjust the plan to your garden

Coastal (Aptos, Capitola, Santa Cruz, Live Oak)

A bed near the coast may be ready for greens while an exposed inland bed is still too hot for easy establishment. Our guide to Santa Cruz microclimates helps you read those differences. Keep temporary shade cloth available if a hot spell arrives, and remove unnecessary shade when conditions ease.

San Lorenzo Valley Sunny Ridges (Boulder Creek, Ben Lomond, Scotts Valley Hills)

Watch the afternoon forecast and how quickly the bed dries. Keep productive summer crops where they fit the plan. New greens may need shade and close moisture checks, but cooler weather alone will not guarantee rapid growth as days shorten.

San Lorenzo Valley Shaded Areas (Felton, Ben Lomond Canyons)

Look at light as well as temperature. A shaded garden may avoid afternoon heat yet receive too little sun for strong fall growth. Choose the brightest usable bed, and check moisture before adding more water.

Inland Valleys (Scotts Valley, Soquel Hills)

Treat exposed inland beds much like sunny ridge gardens during heat. In a low spot, note cooler nights too. A mild planting day is easier on transplants than relying on a townwide seasonal average.

Watsonville and Pajaro Valley

Use the same bed-level checks here: sun, wind, afternoon heat and soil moisture. Marine influence reaches the valley unevenly, so a long tomato season in one garden does not promise the same result in another.

Help cool-season crops through a hot spell

The smallest plants need the closest attention. Make the setup easy to inspect:

Shade new plantings from afternoon sun. Shade cloth, lattice, or even a propped-up board on the west side helps tender seedlings survive.

Water consistently. Soil is still drying out quickly. New plantings need daily attention until established. Our water-wise gardening guide has more strategies for efficient irrigation.

Choose appropriate varieties and remember that heat tolerance is relative, not immunity.

Wait for a cooler spell for spinach and mâche when the bed is still hot.

Start lettuce in a cooler protected place if the outdoor bed will not support germination. Move established seedlings gradually into garden conditions; handling tiny exposed sprouts is needlessly difficult.

Mulch around established seedlings to help retain moisture. Keep mulch clear of stems and do not bury a row of newly sown small seeds.

Local Resources for September Gardening

Seeds and Transplants

Browse Renee's Garden Seeds for vegetable varieties, using packet guidance to match them to your conditions.

Check Sierra Azul Nursery for its current offerings before making a trip. Nursery specialties and stock vary.

Contact San Lorenzo Garden Center about current seasonal transplants.

Ask Mountain Feed & Farm Supply about cover-crop seed and fall planting supplies.

Strawberry Plants

Check Peaceful Valley Farm Supply for variety-specific planting and shipping windows before ordering strawberry plants.

Education

The UC Master Gardeners of Monterey Bay are a local source of growing guidance. Check the current calendar for classes and advice options.

Where to get seeds: For seeds to compare with your planting plan, browse Seeds Now, a seed company selling non-GMO, open-pollinated, and heirloom seed. (Affiliate link, see our disclosure.)

Frequently Asked Questions About September Gardening

Is it too late to plant tomatoes?

A new tomato in September is a late-season experiment, not a reliable recommendation for the county. Remaining warmth, daylight, plant size and variety all matter. For a dependable next crop, prioritize suitable cool-season vegetables and enjoy fruit on tomatoes already established.

Should I pull my tomato plants?

Keep a healthy productive plant if you value its harvest and have room. Remove badly diseased or spent plants, or make space when the next crop matters more. There is no need to clear every tomato because the calendar changed.

Why aren't my lettuce seeds germinating?

Heat may be part of the problem, but check seed age, sowing depth and moisture too. Try a cooler protected start or wait for milder weather rather than repeatedly sowing into the same unfavorable bed.

Is it too late to plant broccoli?

September is within the north-coast planting window in UC IPM's broccoli guidance. Use suitable transplants and variety timing. Do not assume every broccoli must head before winter or that one late-month date rules it out.

When should I plant garlic?

Plan for the local fall planting season and follow the variety's guidance. Ordering seed garlic now can give you time to prepare; there is no need to plant into a hot or poorly drained bed merely to meet a September date.

How do I keep lettuce seeds cool enough to germinate?

Try sowing in a cooler protected place or using temporary shade outdoors while keeping the seed zone moist. Check daily and give emerged seedlings adequate light. Avoid letting a solid covering stay over growing seedlings.

Can I plant strawberries in September?

It depends on the variety, plant type and local planting recommendation. Check with the nursery supplying the plants. Autumn planting can suit some stock, but September is not a universal bare-root planting date or a guarantee of a heavy spring crop.

What if my summer crops are still producing heavily?

Keep using that harvest where space allows. If beds are limited, choose which summer crop is still worthwhile and which fall crop needs its place. The decision belongs to the plants and your priorities, not an all-or-nothing seasonal switch.

Free Gardening Resources

Seasonal Planting Calendar : Month-by-month planting guide for Santa Cruz County, including September's dual-season approach.

Vegetables by Season : Quick reference for which vegetables to plant in the summer-to-fall transition.

Know Your Microclimate Worksheet : Identify your specific growing conditions to understand September temperatures in your location.

Tomato Variety Selector: Compare varieties when planning your next tomato season.

Choose one opening for the next season

You do not have to finish summer before beginning the fall garden. This week, look for:

• A healthy summer crop worth keeping.

• Ripe fruit or tender vegetables ready to pick.

• An opening with enough light for a cool-season crop.

• A seedbed or transplant that needs a moisture check.

• A mild spell when planting will be easier.

Prepare that opening, sow or plant a manageable amount, and see how it establishes. You can make the next decision with a clearer view of both the weather and the harvest.

The garden can change a bed at a time.