[For Home Gardens] How to Grow Delicious Komatsuna in Planters Starting in March

Hello. I am Takahiro Ogawa, an agricultural management supporter.

March has arrived, and while cold days continue, there are times when you can feel the approach of spring. This is exactly what we call the cycle of three cold days and four warm days. It is time to start preparing for spring in your home garden. In this article, I will introduce how to easily start growing Komatsuna (Japanese mustard spinach) in planters for home gardeners.

1. Preparation for Komatsuna Cultivation: Necessary Items and Environment

1.1 Planter: Depth and Size
Komatsuna has shallow roots and a relatively compact growth space, so it can be grown sufficiently in a planter with a depth of about 25 cm. Choose the size of the planter according to the number of plants you want to grow.
・Small planter: 2-3 plants
・Medium planter: 4-6 plants
・Large planter: 8 or more plants
For beginners, it is recommended to start with a medium-sized planter. Planter materials vary, including ceramic, plastic, and wood, which affect breathability and water retention.

1.2 Soil: How to Choose Potting Mix
For Komatsuna cultivation, potting mix for vegetables is ideal. Choose one with a good balance of water retention, breathability, and fertilizer retention.

[Example of Potting Mix Composition]
・Akadama soil: 50%
・Leaf mold: 30%
・Vermiculite: 20%

※pH: Weakly acidic to neutral (pH 6.0-6.5) is optimal.
If using commercially available potting mix, it is recommended to use one that contains organic fertilizer.

1.3 Seeds: Selection of Varieties
Komatsuna seeds can be purchased at home centers or seed shops. Since leaf shape, texture, and growth period vary by variety, choose the one you prefer.
・Leaf shape: Round leaf, sword leaf
・Texture: Soft, crunchy
・Growth period: Early-maturing, mid-maturing, late-maturing

For beginners, early-maturing varieties that are easy to grow are recommended.

1.4 Fertilizer: Base Fertilizer and Top Dressing
Since Komatsuna likes fertilizer, prepare both base fertilizer and top dressing.
(Base Fertilizer)
・Types of fertilizer:
・Slow-release chemical fertilizers or organic fertilizers are suitable.
・Slow-release chemical fertilizers provide stable nutrients for initial growth because their effect lasts for a long time.
・Organic fertilizers also have soil improvement effects and promote the growth of Komatsuna.

・Fertilization amount:
・Although it depends on the soil condition and the type of fertilizer, as a general guideline, apply about 50-100g of chemical fertilizer per square meter.
・If using a pre-mixed potting soil, it already contains base fertilizer, so use less.


Fertilization method:・
Mix the fertilizer into the soil at least 2 weeks before sowing or planting.・For planter cultivation, it is good to spread the fertilizer at the bottom and layer soil on top.

(Top Dressing)
Types of fertilizer:
・Fast-acting chemical fertilizers or liquid fertilizers are suitable.
・Fast-acting chemical fertilizers are effective when growth is stagnant because their effects appear quickly.
・Liquid fertilizers can also be applied to the leaves and can quickly replenish nutrients.

Fertilization amount and timing:
・Apply the first top dressing when the true leaves have reached 2-3 leaves after sowing.
・After that, apply top dressing every 2-3 weeks while observing the growth.
・In planter cultivation, fertilizer is easily depleted, so be sure to apply top dressing frequently.

Fertilization method:
・Apply fertilizer to the base of the plant and mix it lightly with the soil.
・For liquid fertilizer, dilute it and apply it to the base of the plant or spray it on the leaves.

2. Sowing: Timing and Method
The sowing period is generally from mid-March to late April.

2.1 Preparation for Sowing
1. Put potting mix into the planter and moisten it lightly.
2. Level the surface of the soil.

2.2 Sowing Method
1. Scatter the seeds. Sow them evenly so that they do not overlap.
2. Cover the seeds with a thin layer of soil and press lightly.
3. Water gently with a watering can.
4. Continue watering until germination so that the soil does not dry out.

2.3 Management after Germination
・Optimal germination temperature: 15-25°C
・Days to germination: 3-5 days
After germination, move the planter to a sunny place.

3. Thinning: Timing and Method
After germination, when the true leaves have reached 2-3 leaves, thin out the crowded areas.

3.1 Purpose of Thinning
・Ensure spacing between plants and promote growth.
・Improve ventilation and suppress the occurrence of pests and diseases.

3.2 Thinning Method
1. Carefully pull out the seedlings in the crowded areas from the base.
2. Adjust the spacing between plants to about 5-10 cm.
3. Transplant the thinned seedlings to another location or eat them in salads or boiled dishes.

4. Top dressing: Timing and types
Start top dressing once the true leaves reach 5 to 6 in number.

4.1 Timing for top dressing
・About once every 2 weeks during the growing season
・Avoid rainy days or days with strong direct sunlight

4.2 Types of top dressing and application methods
・Liquid fertilizer: Fast-acting with quick results. Dilute and apply to the base of the plants.
・Chemical fertilizer: Slow-release with long-lasting effects. Sprinkle lightly around the base of the plants.

5. Watering: Frequency and precautions
Water Komatsuna thoroughly once the soil has dried out.

5.1 Watering frequency
・Spring: Once every 1 to 2 days
・Summer: Twice or more per day
・Autumn: Once every 2 to 3 days
・Winter: Once every 3 to 4 days

5.2 Watering precautions
・Water in the morning on sunny days.
・Apply water directly to the leaves and the base of the plants.
・Ensure good ventilation after watering.

6. Pest and disease control: Prevention and extermination
For Komatsuna, it is necessary to be careful of pests such as aphids and cutworms.

6.1 Types of pests
・Aphids: Infest leaves and stems, sucking the sap.
・Cutworms: Feed on the leaves.
・Diamondback moths: Lay eggs on leaves, and the larvae feed on the leaves.

6.2 Pest control
・Use insect netting.
・Regularly observe the undersides of leaves and remove any pests found.
・If using insecticides, verify safety and follow the usage and dosage instructions.

6.3 Types of diseases
・Downy mildew: White spots appear on leaves, eventually causing them to wither.
・Soft rot: Stems and leaves rot and emit a foul odor.

6.4 Disease control
・Improve ventilation.
・Be careful not to overwater.
・Remove infected plants as early as possible.

7. Harvesting: Timing and methods
Komatsuna can be harvested when the plant height reaches 20 to 30 cm.

7.1 Harvest timing
・About 30 to 40 days after sowing
・When the leaves are sufficiently large and the plant has become firm.

In this article, I have written about growing Komatsuna in planters for those interested in home gardening. Komatsuna is a relatively easy crop to grow if you provide regular top dressing and take measures against pests.
Please give it a try!

[Related Articles]--------------------------------------------------------------------