What to Plant in April in Sonoma County

April is the turning point in Sonoma County. The rains begin to taper, soil temperatures climb through the 55- to 65-degree range, and the county’s famously compressed growing window opens wide. In a region that stretches from the fog-wrapped ridgelines above Bodega Bay to the warm interior valleys of Healdsburg and Cloverdale, “April” does not mean one thing — it means several, depending on where you garden. Understanding those differences is the key to getting plants in the ground at exactly the right moment.

This guide covers what to plant in April in Sonoma County for home gardens, estate properties, and commercial landscapes alike. Whether you are in the warmth of the Alexander Valley or dealing with the late cool-down that coastal marine influence delivers to the Sebastopol area, April gives you more planting options than any other month.

April in Sonoma County: What the Season Means for Your Garden

Sonoma County sits primarily in USDA Hardiness Zones 9a through 10b, but within those designations lies enormous microclimatic variation. Healdsburg and Cloverdale, warmed by the inland valleys and shielded from marine intrusion, behave much closer to Zone 10a by mid-April — last frost risk is essentially gone by the first week of the month, and daytime highs can already reach into the low 70s. Move west toward Forestville, Sebastopol, or Bodega Bay, and the picture changes considerably. Fog lingers into late morning, soil temperatures run 5 to 10 degrees cooler, and a late cold snap can push into mid-April without much warning.

The practical consequence for gardeners: planting dates that work in Healdsburg on April 1st may need to wait until April 20th or even early May on the coast. Use your microclimate, not a generic zone map, as your primary guide.

April is also the critical transition window from cool-season to warm-season gardening. The cool-season crops planted in fall and winter — brassicas, lettuces, favas, snap peas — are either finishing out or beginning to bolt. At the same time, the soil has accumulated enough warmth to support germination and root establishment for the tender summer crops that need it. Moving too early risks chilling injury and setback. Moving too late costs you weeks of production in a season that already ends abruptly in October with the first heat events.

Rain in April is still possible, though average precipitation drops sharply from February and March levels. Count on natural moisture early in the month but have your irrigation infrastructure ready to activate by mid-April or sooner in the warmer inland zones.

Warm-Season Vegetables to Start in April

April is when the vegetable garden shifts into high gear for summer production. The crops below all require warm soil and frost-free nights — conditions that April delivers, unevenly but reliably, across Sonoma County.

Tomatoes

Tomatoes are the most widely planted summer vegetable in the county and also the most timing-sensitive. In inland zones (Healdsburg, Windsor, Geyserville, Cloverdale), transplants can go in mid-April once nighttime lows are consistently above 50 degrees and soil temperature at six-inch depth reaches 60 degrees. Use a soil thermometer — do not guess. Planting too early into cold soil delays root establishment by weeks even if the plant does not visibly suffer.

In cooler zones (Sebastopol, Graton, the western edge of Santa Rosa), wait until late April or early May. Fog-chilled nights slow fruit set and invite early blight. Row cover or wall-o-water season extenders can give you a 10-day head start if you want to push the timing.

Peppers and Eggplant

Both require even warmer conditions than tomatoes — soil temperatures ideally above 65 degrees for strong establishment. In the warmest parts of the county, late April works. Elsewhere, May is safer. Peppers in particular suffer invisibly in cold soil, producing stunted plants that underperform all season without ever showing an obvious problem.

Summer Squash and Zucchini

Among the most forgiving warm-season crops, summer squash can be direct-seeded in mid-April in inland zones and late April along the coast. They germinate quickly once soil hits 60 degrees, overtake transplants within a week, and produce heavily through June before powdery mildew typically takes over. Two or three plants are more than adequate for most households — do not over-plant.

Cucumbers

Direct seed cucumbers in late April in the warmer interior zones. They need soil temperatures above 65 degrees for reliable germination and do not tolerate even a light frost. In cooler coastal zones, start seeds indoors now and transplant in mid-May. Cucumbers thrive in Sonoma County’s warm, dry summers but require consistent irrigation — any water stress during fruiting leads to bitter cucumbers.

Beans

Bush beans and pole beans are among the easiest vegetables to direct-seed in April. Sow once soil reaches 60 degrees. Bush varieties produce quickly (50–55 days) and make excellent succession plantings — put in a second sowing two to three weeks after the first for an extended harvest. Beans fix nitrogen, making them a natural partner for heavy-feeding crops planted in the same bed the following season.

Summer-Blooming Annuals and Perennials to Plant Now

April is ideal for establishing the summer cutting garden and for planting color beds that will carry through September and October. The mild weather helps roots establish without transplant shock, and plants set in April will be blooming vigorously by June.

Zinnias

One of the best performers in Sonoma County summers, zinnias love heat and thrive in the dry inland conditions of Healdsburg, Windsor, and Cloverdale. Direct sow after mid-April when soil is warm and frost risk has passed. They germinate in 5 to 7 days at 70 degrees and begin blooming in 8 weeks. For cutting gardens, choose tall-stemmed varieties. For border color, compact series work well. In cooler coastal gardens, start indoors now and transplant in May.

Cosmos

Direct-sow cosmos in mid-April throughout the county. They prefer lean, well-drained soil — rich soil produces excessive foliage at the expense of flowers. Cosmos are especially effective in naturalistic and cottage-style plantings and attract beneficial insects throughout the season. They self-seed readily, reducing replanting needs in subsequent years.

Dahlias (Tubers)

April is prime dahlia planting time for Sonoma County. Set tubers directly in the ground once soil has warmed and frost risk is minimal — typically early to mid-April in inland zones and mid- to late April near the coast. Dahlias are heavy feeders and benefit from a low-nitrogen, high-phosphorus fertilizer at planting. In the warm interior valleys, expect first blooms in July. They will continue through the first frost, often carrying color well into November.

Lantana

A workhorse for hot, dry conditions, lantana is one of the most reliable summer performers in Sonoma County’s warmer inland gardens. Set transplants in April when temperatures are reliable. Once established, lantana requires minimal water, tolerates reflected heat from paving, and blooms continuously from late spring through fall. It is not reliably hardy in the coldest spots of the county (low Zone 9a), but in Zones 9b and above, established plants often return from the root even after mild frost dieback.

Agapanthus

An April planting of agapanthus will reward you with its distinctive blue or white globes atop tall stalks by summer. Established clumps are drought-tolerant, deer-resistant, and nearly maintenance-free — qualities that make agapanthus one of the most widely used perennials in Sonoma County commercial and residential landscapes. Divide overcrowded clumps in April as well; divisions replanted immediately establish readily in the warming soil.

Trees and Shrubs: Still Ideal Before Summer Heat

The window for planting trees and shrubs is narrowing in April, but it has not closed. In fact, early to mid-April is still an excellent time to install container-grown trees and shrubs throughout Sonoma County. The soil is moist from winter rains, temperatures are moderate, and plants have several weeks to root in before the stress of summer heat arrives.

Fruit trees — citrus, fig, pomegranate, and stone fruits — go in well in early April in the warmer inland valleys. Ornamental trees including native oaks, ornamental plums, and Chinese pistache can be planted throughout the month. For shrubs, April is ideal for lavender, rosemary, salvia, ceanothus, and other drought-adapted Mediterranean or California-native species. These all benefit from establishing in moderate spring temperatures rather than being stressed immediately by summer heat and limited rainfall.

By late April, avoid planting large container trees in exposed sites without a reliable irrigation setup. The county’s transition into dry season accelerates quickly, and a newly planted tree without water access can go into stress within days during an April heat event.

Bulbs to Plant in April for Summer Bloom

Spring is peak planting time for summer-blooming tender bulbs. Unlike spring bulbs (which go in fall), summer bulbs are planted in April and May to bloom through June, July, and August.

Dahlias

As noted in the annuals section, dahlias planted in April perform extremely well in Sonoma County. The county’s warm summers, combined with cool nights that persist into June, create near-ideal dahlia conditions. Tubers planted in early April in Healdsburg typically produce first bloom by mid-July and continue until frost.

Gladiolus

Plant gladiolus corms every two to three weeks from April through June for a continuous sequence of bloom. They are among the fastest bulbs from planting to flower — 60 to 90 days — making them ideal for succession cutting. In the warm interior valleys, first plantings in early April will produce July flowers. Gladiolus require staking in windy sites, which matters in parts of the county exposed to afternoon valley winds.

Cannas

Cannas thrive in the heat and sun of Sonoma County’s inland gardens. Plant rhizomes in April once soil is warm. They emerge quickly and grow rapidly into bold, tropical-looking specimens that provide dramatic color and structure through the entire summer. Cannas are reliably perennial in Zones 9b and above throughout the county. In the coldest zones, lift rhizomes after frost and store through winter.

What to Finish Before April Ends

April is not only about what to plant — it is about what to wrap up before the window closes.

Bare-root season is over. If you have bare-root roses, fruit trees, or cane berries that have not yet gone in the ground, plant them immediately. Once plants have leafed out significantly, bare-root planting becomes increasingly risky. Any bare-root stock still sitting in packaging should be heeled into the ground or potted up without delay.

Cool-season vegetable sowings are wrapping up. The last reliable sowings of lettuce, spinach, and arugula should go in before mid-April in most of the county. Direct-sow bolt-resistant varieties if you want to push toward late April. After that, the combination of longer days and warming temperatures will trigger bolting within a few weeks of germination, making late plantings largely unproductive.

Overwintered cover crops need to come down. If you grew winter rye, crimson clover, or field peas as cover crops, cut and incorporate them into the soil in early April — at least two to three weeks before planting summer crops. This gives the organic matter time to break down and avoids nitrogen tie-up that can stress young transplants.

Key April Garden Tasks

Beyond planting, April requires a number of management steps that set the stage for a successful summer.

Fertilizing. Apply a balanced slow-release fertilizer to established perennial beds, lawns, and mixed borders in early April. For vegetables, amend beds with compost before transplanting rather than relying on synthetic fertilizers alone — Sonoma County’s native soils, while generally fertile in the valley floors, benefit from consistent organic matter additions.

Irrigation startup and inspection. In most of the county, supplemental irrigation becomes necessary by mid-April. Before the season begins, run each zone and inspect for winter damage — cracked heads, clogged emitters, and shifted risers are common after the wet season. Adjust run times to reflect the increasing evapotranspiration as temperatures climb. Drip-irrigated vegetable gardens should be running by the time transplants go in.

Mulching before the heat arrives. Applying two to three inches of wood chip or shredded bark mulch in April is one of the highest-value tasks in a Sonoma County garden. Mulch applied now moderates soil temperature, retains moisture through the dry season, suppresses summer weeds, and protects tree and shrub roots from heat stress. Leave a gap around plant stems to prevent crown rot.

Pest and disease monitoring. Aphids become active in April as new growth flushes on roses, vegetables, and woody plants. Check the undersides of leaves on susceptible plants weekly. Powdery mildew begins to appear on cucurbits, roses, and certain ornamentals as days warm and nights remain cool — a combination that favors the fungus. Early intervention with neem oil or a dilute bicarbonate solution is far more effective than trying to manage an established infection.

Staking and support. Install tomato cages, dahlia stakes, and bean trellises at planting time rather than retrofitting them after plants are established. Disrupting root zones to add support later causes unnecessary setback.

Professional Planting and Installation Services

April’s compressed planting window rewards those who are prepared and move quickly. At Geared for Growing, we provide residential and commercial planting, soil preparation, irrigation installation and startup, and full landscape installation services throughout Sonoma County. Our team works across the county’s full range of microclimates — from the warm inland valleys to the fog-influenced western zones — and tailors planting timing and plant selection accordingly.

Whether you are establishing a new vegetable garden, installing a summer cutting garden, or completing a larger landscape project before summer heat arrives, our team brings the local knowledge and hands-on experience to do it right. We serve clients in Healdsburg, Windsor, Geyserville, Cloverdale, Santa Rosa, and surrounding areas.

Contact us to schedule a consultation or planting installation for this spring.