Growing Arugula and Mustard Greens in Santa Cruz

When you want greens with personality, arugula and mustard are where you turn. These peppery, spicy leaves wake up salads that might otherwise be bland and add depth to cooked dishes that milder greens can't match. They're among the fastest-growing vegetables you can plant, often ready to harvest in under a month.

Santa Cruz's mild climate is ideal for these cool-season crops. Our moderate temperatures keep the heat from becoming overwhelming, while the long fall-through-spring growing season gives you months of production. Both arugula and mustard greens are remarkably cold-tolerant, often surviving frosts that damage other crops. They're also forgiving of less-than-perfect conditions, making them excellent choices for new gardeners.

This guide covers both arugula (a Mediterranean native) and the diverse world of mustard greens (Asian and European types), with specific guidance for growing them in Santa Cruz County's varied microclimates.

Understanding Arugula

Arugula (also called rocket, roquette, or rucola) has become a salad bar staple, but homegrown arugula offers a revelation in flavor. The leaves have a distinctive peppery, nutty taste that ranges from mild in young leaves to quite spicy in mature ones. Unlike the often tired arugula in stores, fresh-picked leaves are crisp and vibrant.

Types of Arugula

Common arugula (Eruca sativa) is what you'll find in most seed catalogs. It grows quickly (21 to 40 days), has deeply lobed leaves, and bolts readily in warm weather or long days. This is the arugula to plant for fast harvests and baby greens.

Wild arugula (Diplotaxis tenuifolia) is a different species with narrower, more deeply cut leaves and a more intense, peppery flavor. It's slower-growing (40 to 60 days) but much more heat-tolerant and slower to bolt. Wild arugula is perennial in our climate, returning year after year in mild winters. It's the better choice for extended harvests and summer production.

According to UC Agriculture and Natural Resources, common arugula bolts quickly when temperatures exceed 75°F or day length exceeds 14 hours, while wild arugula tolerates more heat before bolting.

Type	Days to Harvest	Flavor	Bolt Resistance	Best Use
Common Arugula	21-40	Mild to peppery	Low	Baby greens, quick harvests
Wild Arugula	40-60	Intense, spicy	Good	Extended harvest, cut-and-come-again

Arugula Varieties Worth Growing

'Astro' is a common arugula with mild flavor and good bolt resistance for its type. It's a good choice for spring plantings.

'Roquette' is the standard common arugula with classic flavor. Quick to mature but also quick to bolt.

'Sylvetta' is a popular wild arugula variety with narrow, deeply lobed leaves and intense flavor. It overwinters well in Santa Cruz.

'Wasabi' is a common arugula variety bred for extra heat. The name isn't an exaggeration; this variety has real kick.

Understanding Mustard Greens

Mustard greens encompass a vast family of brassicas grown for their peppery, often spicy leaves. From mild Asian varieties to fiery Southern types, there's a mustard for every taste preference and culinary use.

Types of Mustard Greens

Asian mustards tend to be milder and more versatile. They're often eaten raw in salads when young or cooked when mature. Many have been developed for bolt resistance and tender texture. Examples include mizuna, mibuna, and komatsuna (covered in the Asian greens article), as well as types like 'Osaka Purple' and 'Red Giant'.

Southern mustards are traditional varieties with more intense heat. They're typically cooked rather than eaten raw, often braised with pork or bacon in classic Southern preparations. Varieties include 'Southern Giant Curled' and 'Florida Broadleaf'.

Indian mustards (Brassica juncea) include both mild and hot varieties. The seeds are used to make mustard condiment, and the leaves are popular in Indian cooking. 'Green Wave' and 'Red Giant' are common varieties.

Ethiopian mustard (Brassica carinata) is less common but worth seeking out. It's notably heat-tolerant and slow to bolt, with large, productive plants.

Variety	Type	Days	Heat Level	Notes
Red Giant	Asian	40-50	Moderate	Beautiful purple-red leaves, good cold tolerance
Osaka Purple	Asian	40	Mild to Moderate	Purple veins on green leaves, mild when young
Southern Giant Curled	Southern	45-50	Hot	Classic cooking mustard, frilly leaves
Florida Broadleaf	Southern	45	Hot	Large flat leaves, slower to bolt
Green Wave	Indian	45	Hot	Frilly leaves, good bolt resistance
Ruby Streaks	Asian	40	Mild	Deeply cut purple leaves, excellent in salads
Golden Frill	Asian	40	Mild	Chartreuse finely cut leaves, mild flavor

When to Plant in Santa Cruz

Both arugula and mustard greens follow similar timing patterns, with fall being the prime season and spring requiring more careful variety selection.

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

Fall through Spring (September through April) is the main growing window. Plant every two to three weeks for continuous harvest. Growth slows in the darkest winter weeks but doesn't stop.

Summer (May through August) is challenging for common arugula and most mustards. Wild arugula handles summer better and may continue producing in coastal fog zones. Some gardeners have success with afternoon shade and consistent watering.

Inland Areas (Scotts Valley, Boulder Creek, Soquel Hills)

Fall through Early Spring (September through March) is most reliable. Plant bolt-resistant varieties for any spring plantings.

Summer is not recommended except for wild arugula in protected, shaded spots.

Under the Redwoods (Felton, Ben Lomond Canyons)

The cool shade extends the season compared to sunny inland areas. You may get away with planting into April and harvesting into early summer in shaded gardens.

Pajaro Valley and Watsonville

Fall through Winter (October through February) is the most reliable window. The warmer climate shortens the season at both ends.

Growing Arugula and Mustard Greens

Direct Sowing

Both arugula and mustard greens are best direct-sown. The seeds are small and germinate quickly (5 to 10 days). Broadcast seeds over prepared soil or plant in rows, covering with one-quarter inch of soil. Thin to appropriate spacing once seedlings emerge.

For baby greens, plant densely (seeds nearly touching) and harvest entire patches when leaves reach 3 to 4 inches.

For cut-and-come-again harvesting, thin plants to 4 to 6 inches apart and harvest outer leaves while leaving the center to regrow.

For full-sized plants, thin to 8 to 12 inches apart and harvest whole plants or individual leaves as needed.

Soil and Fertilizer

Both crops prefer fertile, well-drained soil amended with compost. They're moderate feeders; excessive nitrogen can produce rank-tasting leaves. A single application of balanced organic fertilizer at planting is usually sufficient for quick-maturing crops. For longer-term plantings like wild arugula, side-dress with compost every few weeks.

Watering

Consistent moisture produces the best-tasting leaves. Water stress concentrates the peppery compounds, making leaves unpleasantly hot and tough. Water regularly to keep soil evenly moist, especially during dry periods. Mulch helps maintain moisture and keeps leaves clean.

Harvesting for Best Flavor

The age of the leaf dramatically affects flavor intensity. Young leaves are milder; mature leaves are more peppery (or hot, in the case of mustards). Harvesting strategy depends on how you want to use the greens.

For salads: Harvest young leaves (2 to 4 inches) for mild flavor that won't overwhelm other ingredients. Mix with milder lettuces to balance the heat.

For cooking: Larger, more mature leaves hold up better to heat and contribute more flavor. The heat mellows when cooked, so use bolder leaves for braising, stir-fries, and soups.

For maximum production: Use the cut-and-come-again method, harvesting outer leaves and allowing the center to keep growing. This extends harvest for weeks or even months.

When plants bolt: The flowers of both arugula and mustard are edible and tasty. Arugula flowers have a mild, nutty flavor perfect for garnishing. Mustard flowers are spicier. Harvest flowering stems before flowers fully open for best flavor and texture.

Managing Heat and Bitterness

Both arugula and mustard greens become more pungent when stressed. Heat, drought, and bolting all intensify flavor, sometimes unpleasantly.

Plant at the right time. Fall plantings grow during cooling weather and produce milder leaves. Spring plantings often turn harsh as temperatures warm.

Keep plants well-watered. Drought stress concentrates peppery compounds. Even brief dry spells affect flavor.

Provide afternoon shade in late spring. Shade cloth or a position that gets morning sun and afternoon shade extends the season.

Harvest promptly. Don't let leaves get overly mature. Pick regularly to encourage tender new growth.

Choose appropriate varieties. Wild arugula is more heat-tolerant than common arugula. Milder mustard varieties like 'Ruby Streaks' and 'Osaka Purple' stay pleasant longer than hotter types like 'Southern Giant Curled'.

Pest Management

Arugula and mustard face the same pests as other brassicas.

Flea beetles create tiny shot-holes in leaves. They're more active in warm weather. Floating row cover prevents damage. Mature plants usually tolerate some flea beetle damage without significant harm.

Aphids can colonize arugula and mustard, especially late in the season. Check undersides of leaves and wash or spray off with water.

Caterpillars (cabbage worms and loopers) chew larger holes. Row cover prevents egg-laying. Bt spray treats existing infestations.

Slugs and snails love tender greens. Handpick, use beer traps, or apply iron phosphate bait.

Cooking with Arugula and Mustard Greens

Raw arugula is the classic salad green. Toss with olive oil, lemon juice, shaved parmesan, and toasted pine nuts. Mix with mild lettuces if the flavor is too strong alone. Add to sandwiches and pizzas (after cooking, as a topping).

Cooked arugula wilts quickly like spinach. Sauté briefly with garlic and olive oil, or stir into hot pasta at the last minute. The peppery flavor mellows with heat.

Mild mustard greens (Ruby Streaks, Golden Frill, Osaka Purple) work well raw in salads. Their texture is more substantial than arugula.

Hot mustard greens (Southern Giant Curled, Green Wave) are best cooked. Traditional Southern preparations braise them low and slow with pork, but they're also excellent in stir-fries, soups, and Indian dishes. The heat mellows significantly with cooking.

Mustard green stems are edible and add crunch. Chop and cook them a minute or two before adding the leaves.

Where to Find Seeds

Renee's Garden Seeds offers arugula varieties tested in their Felton trial gardens.

Kitazawa Seed Company has an excellent selection of Asian mustards.

Southern Exposure Seed Exchange carries traditional Southern mustard varieties.

Johnny's Selected Seeds offers both common and wild arugula plus many mustard varieties.

Local nurseries including Mountain Feed and Farm Supply and San Lorenzo Garden Center carry basic arugula and mustard seeds seasonally.

Frequently Asked Questions

Why is my arugula so bitter and spicy?

Stress intensifies arugula's peppery flavor. Heat, drought, and bolting all make leaves more pungent. Water consistently, provide afternoon shade in warm weather, and harvest young leaves for milder flavor. If plants have bolted, the leaves will be quite hot; harvest the milder flowers instead.

What's the difference between common and wild arugula?

Common arugula (Eruca sativa) grows quickly, has broad lobed leaves, and bolts readily. Wild arugula (Diplotaxis tenuifolia) grows more slowly, has narrow deeply-cut leaves, has more intense flavor, and is much more heat and bolt-resistant. Wild arugula is also perennial in our climate.

Can I grow arugula in summer?

Common arugula bolts quickly in summer heat. Wild arugula is more heat-tolerant and may produce through summer in coastal areas with afternoon shade and consistent watering. For reliable summer greens, switch to heat-tolerant alternatives like Malabar spinach.

How do I make mustard greens less spicy?

Harvest young leaves, which are milder. Cook the greens, which significantly reduces heat. Blanching briefly in boiling water before sautéing removes even more bite. Choose naturally milder varieties like 'Ruby Streaks' or 'Osaka Purple'.

Will arugula and mustard self-seed?

Yes, both readily self-seed if allowed to flower. This can be a feature (free plants!) or a nuisance depending on your garden style. Remove flower stalks before seeds mature if you don't want volunteers. Many gardeners appreciate the self-sowing nature, which provides ongoing harvests with minimal effort.

Can I eat the flowers?

Absolutely. Arugula flowers are mild and nutty, excellent as a garnish or in salads. Mustard flowers are spicier but still edible. Both are pretty additions to dishes.

How cold-tolerant are these greens?

Both arugula and mustard greens are quite cold-hardy, surviving temperatures into the mid-20s with minimal damage. Light frost often improves flavor by converting starches to sugars. Heavy frost may damage leaves but usually doesn't kill plants, which regrow from the crown.

What's the fastest green I can grow?

Common arugula is one of the fastest vegetables, with baby leaves ready in 21 days and full-size leaves in 40 days. Some mustard greens are nearly as fast at 30 to 40 days to harvest.

Free Resources

Download these guides from our Garden Toolkit:

Seasonal Planting Calendar includes timing for arugula and mustard greens in each microclimate.

Succession Planting Guide helps you plan continuous harvests.

Garden Troubleshooting Guide covers pest identification and management.

Related Articles

Best Lettuce Varieties for Santa Cruz Microclimates covers milder salad greens to mix with peppery arugula.

Growing Asian Greens in Santa Cruz explores related brassicas like mizuna and komatsuna.

Cut-and-Come-Again Greens: Maximizing Your Harvest explains the technique that keeps arugula producing.

Greens Troubleshooting: Bolting, Bitterness, and Pests provides solutions to common problems.