Shanghai Green Mini Bok Choi

Introduction to Mustard and Asian Greens

Historical and Cultural Significance

• Mizuna: Native to East Asia, particularly Japan, mizuna has been an essential part of Japanese cuisine for centuries, used in salads, soups, and stir-fries.
• Tatsoi: Originating in China, tatsoi is a staple in Asian culinary traditions, known for its mild, slightly sweet flavor.
• Bok Choi: A traditional Chinese vegetable, bok choi is versatile and widely used in a variety of Asian dishes.
• General Adaptation: These greens have become popular worldwide, valued for their nutritional content and adaptability to different climates.

Botanical Description

• Growth Habit: These greens generally have a rosette growth habit, with leaves varying in size, texture, and color.
• Leaf Description: Mizuna has deeply serrated, feathery leaves, tatsoi features rounded, spoon-shaped leaves, and bok choi is known for its broad, white stems and dark green leaves. Mustard greens in general can come in a variety of shapes, sizes, colors, and levels of peppery spiciness. 

Site Selection and Soil Preparation

Sunlight and Location

• Full to partial sun is ideal for optimal growth.
• Avoid areas prone to waterlogging.

Soil Requirements

• Prefer well-drained, fertile loamy soil.
• Ideal soil pH is between 6.0-7.0.

Soil Preparation

• Incorporate organic matter, such as compost, to improve soil structure and fertility.
• Ensure good drainage to prevent root diseases.

Planting

Seed Selection

• Choose high-quality, disease-free seeds from reputable sources.
• Consider disease resistance and growth duration when selecting varieties.

Sowing

• Direct sow in the garden (good for warmer weather) or start seeds indoors for early crops.
• Sow seeds about 1/4 inch deep, spacing according to variety specifications. Generally, baby greens can be grown at a seeding rate of about 3 seeds per inch, with rows 4’ apart, or 2” bands of seed spaced at least 6” apart. If growing for full sized (and fuller flavor) leaves or whole bunched plants, consider spacing at least 4” apart. Bok choi should be spaced 4-6” for baby production and 8-12” for full size. 

Planting Time

• Ideal for early spring planting; can also be planted in late summer for a fall harvest.
• All can tolerate light frosts, making them suitable for extended growing seasons. Some types, such as Mizuna, and especially Tatsoi, are very cold-hardy and excellent for very early spring, late fall, and winter production.

Irrigation

Water Requirements

• Regular watering is crucial, especially during dry periods.
• Avoid overwatering; consistent moisture is key.
• Watering at the base or with drip irrigation will help reduce disease potential. 

Nutrient Management

Soil Testing and Fertilization

• Conduct a soil test to determine nutrient needs.
• Use a balanced fertilizer, ensuring adequate nitrogen for leaf growth.

The nutrient requirements, particularly Nitrogen (N), Phosphorus (P), and Potassium (K) (commonly referred to as NPK), for Asian and mustard greens like Mizuna, Tatsoi, and Bok Choi are important for optimal growth and yield. However, specific NPK recommendations can vary based on soil type, previous crop history, and local environmental conditions. Here are general guidelines that can be adjusted based on soil test results and specific growing conditions:

Nitrogen (N):

• Asian and mustard greens are leafy vegetables, so they require a good amount of nitrogen for healthy leaf growth.
• A general recommendation is to apply about 80 to 120 pounds of nitrogen per acre.
• Nitrogen should be applied in split applications, with half at planting and the rest as a side-dress a few weeks after germination or transplanting.

Phosphorus (P):

Phosphorus is essential for root development and early plant vigor.

A typical application rate might be around 40 to 60 pounds of P2O5 (phosphorus pentoxide) per acre.

The exact amount depends heavily on soil test results, as phosphorus can accumulate in the soil from year to year.

• Potassium (K):
• Potassium is crucial for overall plant health and disease resistance.
• Application rates are generally in the range of 60 to 80 pounds of K2O (potassium oxide) per acre.
• As with phosphorus, soil test results are vital for determining the exact potassium needs.

Additional Considerations:

• Soil Testing: Always start with a soil test to determine the existing nutrient levels and pH of your soil. This will help you customize the fertilizer application to your specific needs.
• Organic Amendments: If you are growing organically, you might use compost, manure, and other organic fertilizers. The nutrient content of these can vary widely, so consider having them tested if you are using large or consistent amounts.
• Fertilizer Formulas: Use a balanced fertilizer as a base, but adjust based on your soil test results and crop needs. For example, a fertilizer with higher nitrogen content is beneficial early in the growth cycle.
• Local Extension Services: Consult with your local agricultural extension service for tailored advice. They can provide specific recommendations based on regional soil types and growing conditions.

Remember, these are general guidelines and should be adjusted according to your specific circumstances. Over-fertilization can be as detrimental as under-fertilization, so precise application based on soil conditions is key.

Organic Amendments

• Consider using compost or well-rotted manure to enrich the soil.

Pest and Disease Management

Common Pests

Aphids:

• Description: Small, soft-bodied insects that feed on plant sap, often found on the undersides of leaves.
• Prevention: Encourage beneficial insects like ladybugs or use reflective mulch to deter them.
• Organic Control: Neem oil, insecticidal soaps, or a strong water spray can be effective.

Flea Beetles:

Description: Small, jumping beetles that eat small holes in leaves.

Prevention: Use row covers to protect plants, especially young seedlings.

Organic Control: Pyrethrin-based insecticides, or trap crops (like radishes) to divert them. Prevention is the best option. 

Beneficial nematodes can reduce populations over time. 

• Cabbage Loopers and Worms:
• Description: Caterpillars that chew large holes in leaves.
• Prevention: Regularly check plants and handpick caterpillars.
• Organic Control: Bacillus thuringiensis (Bt) is a naturally occurring bacterium that's effective against caterpillars.

Common Diseases

Downy Mildew:

• Description: A fungal disease causing yellow spots on leaves and fluffy white growth underneath.
• Prevention: Ensure good air circulation, avoid overhead watering, and rotate crops.
• Organic Control: Copper-based fungicides can be used preventatively.

Clubroot:

Description: A soil-borne disease causing swollen and distorted roots, leading to stunted growth.

Prevention: Maintain soil pH around 7.0, practice crop rotation, and sanitize tools.

Organic Control: There are no effective organic treatments once plants are infected; prevention is key.

• Black Rot:
• Description: Bacteria causing yellowing and wilting of leaves, often starting at the edges.
• Prevention: Use disease-free seeds, ensure good drainage, and avoid working in wet fields.
• Organic Control: Remove and destroy affected plants, and use copper-based bactericides as a preventive measure.

Additional Organic Pest and Disease Management Strategies

• Biological Control: Introduce or encourage natural predators and parasites that attack specific pests.
• Cultural Control: Practice good sanitation, crop rotation, and proper spacing to improve air circulation.
• Physical Barriers: Floating row covers can protect plants from insect pests.
• Soil Health: Healthy soil leads to stronger plants that are more resistant to pests and diseases. Incorporate organic matter to improve soil structure and nutrient content.
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Harvesting and Post-Harvest

Harvesting

• Mizuna and Tatsoi: Harvest young leaves for salads or mature for cooking. Use a cut-and-come-again method.
• Bok Choi: Harvest size depends on variety; baby bok choi are good harvested when the base of the rosette is about 3 inches in diameter, either the outer leaves or the whole plant.

Post-Harvest Handling

• Handle leaves gently to prevent bruising.
• Cool immediately after harvest to maintain freshness, ideally by hydrocooling and doing an initial gentle wash in cold water, followed by drying before storage
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Storage

• Store in a cool, humid environment.
• Generally, these greens have a relatively short shelf life and are best used fresh. Some can be frozen for use as steamed or sauteed greens. 

Varietal Selection

Considerations for Selection

• Flavor preferences: mild vs. peppery.
• Leaf size and texture.
• Growth rate and heat tolerance.
• Disease resistance, especially to common local diseases.