Intermediate Spinach Growing: Varieties, Succession Planting, and Season Extension

Beyond the Basics: Intermediate Spinach Growing

Now that you've successfully grown spinach, it's time to expand your skills. This guide covers variety selection for specific purposes, succession planting for continuous harvests, disease management, and techniques to extend your growing season far beyond the typical spring and fall windows.

Deep Dive into Spinach Varieties

Understanding Leaf Types and Their Uses

Savoy (Heavily Crinkled)

• Best for fresh eating—superior flavor and texture
• Dark green, thick leaves hold dressings well
• Higher chlorophyll and nutrient density
• Challenging to wash thoroughly
• Grows closer to ground (more soil contact)

Best varieties: Bloomsdale Long Standing, Tyee, Escalade

Semi-Savoy (Slightly Crinkled)

• Excellent balance of flavor and convenience
• Upright growth habit keeps leaves cleaner
• Good disease resistance
• Preferred by market growers
• Easier mechanical harvesting

Best varieties: Melody (All-America Selection winner 1977), Avon, Regal

Flat-Leaf/Smooth

• Industry standard for baby leaf production
• Easiest to wash and process
• Upright habit allows high-density planting
• Preferred for canning, freezing, and processing
• Quick growing but less complex flavor

Best varieties: Space, Gazelle, Renegade

Bolt Resistance: The Critical Factor

Bolting is spinach's biggest challenge. Understanding what triggers bolting helps you select appropriate varieties:

Bolting triggers:

1. Day length: Primary trigger—bolting starts when days exceed 12.5-15 hours
2. Temperature: Days above 75°F (24°C) accelerate bolting
3. Vernalization: Cold exposure of young plants can trigger bolting
4. Stress: Water stress, crowding, and transplant shock

Highly Bolt-Resistant Varieties:

Warning: Even bolt-resistant varieties will bolt in long days. "Bolt resistant" means slower to bolt, not bolt-proof.

Disease Resistance Considerations

Downy Mildew (Peronospora effusa): The most serious spinach disease. New races appear regularly, making resistance temporary.

Important: New downy mildew races (currently up to race 20+) are continually emerging. Check seed catalogs for the latest resistance information.

Succession Planting Mastery

The Concept

Instead of planting all your spinach at once (and harvesting it all at once), make multiple smaller plantings for a continuous supply:

Succession Planting Schedule

Spring Schedule:

• Planting 1: 6 weeks before last frost
• Planting 2: 4 weeks before last frost
• Planting 3: 2 weeks before last frost
• Planting 4: At last frost (use bolt-resistant varieties)

Fall Schedule:

• Planting 1: 10 weeks before first frost
• Planting 2: 8 weeks before first frost
• Planting 3: 6 weeks before first frost (for overwintering)

Calculating Planting Amounts

For fresh eating (family of 4):

• Sow 2-3 feet of row every 2-3 weeks
• Or plant 12-15 plants per succession
• Expect 4-6 ounces per plant at maturity

For baby leaf production:

• Plant 100-150 seeds per succession
• Dense seeding: 60 seeds per square foot
• Harvest at 3-4 weeks

For market growing:

• Plan 50-100 feet of row per week of sales
• Baby leaf: 15-20 lbs per 100 row feet
• Full-size: 25-35 lbs per 100 row feet

Season Extension Techniques

Cold Protection Methods

Row Covers (Floating)

• Provide 2-4°F frost protection
• Allow rain and light penetration
• Exclude pests
• Remove when temperatures exceed 75°F
• Reemay or Agribon are common brands

Cold Frames

• Glass or plastic-covered boxes
• Provide 10-15°F protection
• Excellent for overwintering
• Ventilate on sunny days above 40°F
• Ideal for fall-to-spring production

Low Tunnels

• Wire hoops with plastic or fabric
• More protection than row covers
• Easy to install and remove
• Good for extending fall harvest

High Tunnels/Hoop Houses

• Walk-in structures
• Excellent overwintering results
• Harvest all winter in zones 6-7
• Year-round production in zones 5+

Overwintering Spinach

The Technique:

1. Plant timing: Sow 6-8 weeks before first frost
2. Target size: Plants should have 4-6 true leaves before hard freeze
3. Protection: Cover with row cover, straw mulch, or cold frame
4. Winter care: Water occasionally during thaws; keep covered
5. Spring harvest: Plants resume growth as days lengthen (February-March)

Why it works: Spinach is extremely cold hardy (to 15°F/-9°C), and young plants survive better than mature ones. The plant essentially pauses growth over winter, then explodes in spring.

Best overwintering varieties:

• Bloomsdale Long Standing
• Tyee
• Giant Winter

Heat Management for Late Spring

Techniques to delay bolting:

1. Shade cloth: 30-40% shade cloth reduces heat stress
2. Mulching: Keeps roots 5-10°F cooler
3. Dense planting: Self-shading effect
4. Afternoon shade: Plant where buildings/trees provide afternoon shade
5. Irrigation: Keep soil consistently moist—water stress accelerates bolting
6. Early morning harvest: Cool leaves store better

Optimizing Growing Conditions

Soil Management

Ideal soil profile:

• pH: 6.5-6.8 (critical—test every season)
• Organic matter: 3-5%
• Nitrogen: High availability
• Drainage: Good, but moisture retentive

Pre-plant amendments:

• Acidic soil (pH <6.5): Add 1-2 lbs lime per 100 sq ft, incorporate 2-3 months before planting
• Low nitrogen: Blood meal (12-0-0) at 2-4 lbs per 100 sq ft
• Heavy clay: Add 2-4 inches compost
• Sandy soil: Add organic matter for moisture retention

Irrigation Precision

Water requirements:

• 1-1.5 inches per week
• Consistent moisture is key—fluctuation causes bitterness
• Drip irrigation preferred (keeps leaves dry)
• Water early in day if using overhead irrigation

Critical periods:

• Germination: Keep surface consistently moist
• Establishment: Don't let young plants wilt
• Pre-harvest: Adequate water = tender, sweet leaves

Fertilization Strategy

Nitrogen is king for spinach, but too much causes problems:

Balanced approach:

• Pre-plant: 2 lbs 10-10-10 per 100 sq ft
• Side-dress: 2 oz nitrogen per 100 sq ft at 3-4 weeks
• Foliar feed: Fish emulsion every 2 weeks (optional)

Caution: Excessive nitrogen increases nitrate accumulation in leaves, which is undesirable. Don't overfertilize.

Pest Management

Common Spinach Pests

Leafminers (Pegomya hyoscyami)

Identification:

• Small gray flies lay eggs in leaf tissue
• Larvae create winding tunnels (mines) between leaf surfaces
• Damage makes leaves unmarketable

Management:

• Row covers: Most effective prevention
• Remove and destroy affected leaves
• Parasitic wasps (Diglyphus spp.) provide biological control
• Rotate away from spinach family for 1+ year

Aphids

Identification:

• Green, yellow, or gray soft-bodied insects
• Colony on undersides of leaves
• Honeydew and sooty mold
• Vector for viruses

Management:

• Strong water spray dislodges most aphids
• Encourage natural enemies (ladybugs, lacewings)
• Insecticidal soap for heavy infestations
• Avoid excessive nitrogen (promotes aphid reproduction)

Slugs and Snails

Management:

• Hand-pick at night
• Iron phosphate bait (OMRI listed)
• Diatomaceous earth barriers
• Beer traps

Harvest and Post-Harvest Handling

Maximizing Quality

Harvest timing:

• Early morning: Maximum turgor, best storage
• Before bolting: Flavor deteriorates rapidly once flower stalk forms
• Cool temperatures: Below 75°F ideal

Harvest methods:

• Cut-and-come-again: Take outer leaves only, leaving growing point
• One-cut harvest: Cut all leaves 1 inch above crown
• Full harvest: Cut entire plant at soil line

Post-Harvest Handling

Immediate cooling is critical:

• Spinach respiration rate is very high
• Quality deteriorates rapidly at warm temperatures
• Target: Cool to 32-36°F within 1 hour

Storage conditions:

• Temperature: 32-34°F (0-1°C)
• Relative humidity: 95-98%
• Shelf life: 10-14 days at optimal conditions
• Avoid ethylene exposure (accelerates yellowing)

Baby spinach:

• Even more perishable than mature leaves
• Higher respiration rate
• Best used within 7 days of harvest

Growing for Market

Baby Leaf Production

Planting:

• Seeding rate: 60-100 seeds per square foot
• Row spacing: 2-3 inch bands, 4-6 inches between bands
• Depth: 1/4 inch
• Days to harvest: 21-28 days

Harvest:

• Cut at 2-3 inches tall
• Leave 1/2 inch stubble for regrowth (one additional cut possible)
• Mechanical harvest available at scale

Yield: 15-20 lbs per 100 square feet

Full-Size Production

Planting:

• Seeding rate: 15-20 seeds per foot
• Thin to 3-4 inches
• Row spacing: 12-18 inches
• Days to harvest: 40-50 days

Yield: 25-35 lbs per 100 row feet

Troubleshooting Advanced Problems

Record Keeping

Track these variables to improve your results:

• Variety and seed source
• Planting and harvest dates
• Temperatures (soil and air)
• Irrigation amounts
• Pest/disease observations
• Yield data
• Flavor and quality notes

Moving to Advanced Growing

You're ready for expert techniques when you can:

• Successfully grow spinach in spring AND fall
• Manage downy mildew without crop loss
• Extend your season with cold protection
• Produce consistent, high-quality harvests
• Understand the variety differences

Next steps: Explore hydroponic production, intensive market growing systems, and the science of bolting control.