Growing SL28 coffee rootstock is an essential step for farmers and nursery operators who want to produce grafted coffee seedlings. SL28 is widely used as a rootstock in Kenya because it has deep roots, excellent drought tolerance, and strong plant vigor.

Many nurseries graft improved varieties such as Ruiru 11 or Batian onto SL28 rootstock to produce seedlings that combine:

• Strong roots
• High yields
• Disease resistance
• Better drought tolerance

This Standard Operating Procedure (SOP) explains how to grow SL28 rootstock seedlings from seed in a nursery.

Stage 1: Planning and Nursery Setup

Step 1: Choose a Suitable Nursery Location

Select a location with:

• Partial shade
• Reliable water supply
• Good drainage
• Protection from strong wind and animals

Avoid areas with waterlogging, as coffee seedlings are sensitive to excess moisture.

Step 2: Construct a Nursery Shade

Coffee seedlings require protection from strong sunlight.

Use materials such as:

• Shade net
• Banana leaves
• Grass thatch
• Shade cloth

Recommended shade level: 50–60% shade

The nursery should also have raised beds to prevent flooding.

Stage 2: Seed Selection and Preparation

Step 3: Obtain Certified SL28 Seeds

Purchase seeds from trusted sources such as:

• Coffee Research Institute nurseries
• Certified seed suppliers
• Established coffee farms

Good seeds should be:

• Fully mature
• Disease-free
• Fresh (recently harvested)

Avoid old seeds because coffee seeds lose viability quickly.

Step 4: Prepare the Seeds

Before planting:

1. Remove the outer pulp if using fresh cherries.
2. Wash seeds thoroughly.
3. Soak seeds in clean water for 24 hours.

This improves germination.

Stage 3: Preparing the Seedbed

Step 5: Prepare a Germination Bed

Create a raised germination bed with:

• Fine sand or sandy soil
• Well-drained structure
• Width: about 1 meter

The bed should be slightly raised to improve drainage.

Step 6: Plant the Seeds

Plant seeds carefully:

• Place seeds flat side down
• Spacing: about 2–3 cm apart
• Cover lightly with sand or fine soil

Water gently after planting.

Stage 4: Seed Germination

Step 7: Maintain Moisture

Water the seedbed daily but lightly.

The soil should remain moist but not waterlogged.

Seeds usually germinate in:

• 45–60 days

During germination, the seedlings will emerge in the “matchstick stage.”

Stage 5: Transplanting to Polybags

Step 8: Prepare Nursery Polybags

Fill polybags with a mixture of:

• Topsoil (forest soil preferred)
• Well-decomposed manure
• Sand for drainage

Recommended ratio:3 parts soil : 1 part manure : 1 part sand

Typical polybag size:6 × 9 inches

Step 9: Transplant Germinated Seedlings

Transplant seedlings when they reach the matchstick stage.

Procedure:

1. Water the germination bed before lifting seedlings.
2. Carefully lift seedlings without damaging roots.
3. Plant one seedling per polybag.

Ensure the root is straight and not bent.

Water immediately after transplanting.

Stage 6: Nursery Management

Step 10: Watering

Water seedlings:

• Once daily during dry periods
• Less frequently during rainy seasons

Avoid overwatering.

Step 11: Weed Control

Remove weeds regularly.

Weeds compete with seedlings for nutrients and water.

Step 12: Pest and Disease Control

Watch for common nursery pests such as:

• Aphids
• Leaf miners
• Cutworms

Control methods include:

• Organic sprays
• Approved pesticides if necessary

Good nursery hygiene is critical.

Stage 7: Preparing for Grafting

Step 13: Grow Seedlings to Grafting Stage

SL28 rootstocks are ready for grafting when they:

• Are 8–12 weeks old
• Have stem thickness similar to a matchstick or pencil
• Are healthy and vigorous

At this stage they are ideal for grafting varieties such as Ruiru 11.

Stage 8: Hardening and Maintenance

Step 14: Maintain Strong Seedlings

Continue proper care:

• Moderate watering
• Adequate shade
• Removal of weak plants

Healthy rootstock ensures high graft success rates.

Timeline Summary

Total time to grafting stage: about 2–3 months

Cost Estimate for a Small Nursery (1,000 Rootstocks)

Estimated startup cost:

Ksh 15,000 – 20,000

Profit Opportunity for Coffee Nurseries

Example:

1,000 grafted seedlings sold at Ksh 100 each

Revenue: Ksh 100,000

Estimated production cost: Ksh 30,000 – 40,000

Potential profit:Ksh 60,000+

This is why many small nurseries in Kenya specialize in coffee rootstock and grafted seedlings.

Tips for Success

✔ Always use fresh SL28 seeds

✔ Maintain proper nursery shade

✔ Avoid waterlogging

✔ Use fertile topsoil with manure

✔ Handle seedlings gently during transplanting

✔ Maintain good nursery hygiene

Final Thoughts

Growing SL28 rootstock seedlings is the foundation of a successful coffee grafting nursery. With proper nursery management, farmers and agribusiness entrepreneurs can produce thousands of healthy rootstocks that are later grafted with high-yielding varieties like Ruiru 11 or Batian.

For anyone interested in agricultural entrepreneurship, a coffee seedling nursery can become a profitable small-space business venture in Kenya.