Ornamental plant production is a vital aspect of Kenya’s horticulture sector, contributing significantly to urban landscaping, commercial nurseries, and environmental beautification. Successful establishment of ornamental plants requires meticulous preparation of the planting site to ensure good growth conditions and long-term sustainability. This chapter focuses on the essential steps and considerations involved in preparing land specifically for ornamental plant production, tailored to the Kenyan context where soil types, climate variability, and resource availability influence horticultural practices.

2.1 Preparation of the Land

Land preparation is a critical first step in establishing ornamental plants as it directly affects root development, water availability, and nutrient uptake. In Kenya, where soils vary from sandy in coastal regions to heavy clays in the highlands, adapting preparation techniques to local conditions ensures optimal plant establishment. Proper land preparation also facilitates pest and weed control, which are major challenges in maintaining healthy ornamental plantings in urban and rural settings.

2.1.1 Assessing the Site and Soil Conditions

Understanding the specific characteristics of the site and soil is fundamental before any physical preparation begins. This assessment guides decisions on necessary amendments and preparation methods to create an environment conducive to ornamental plant growth.

Soil Texture and Structure

Soil texture refers to the proportion of sand, silt, and clay particles, affecting water retention and aeration. For example, sandy soils common in parts of Mombasa drain quickly but hold fewer nutrients, requiring organic matter addition. Conversely, clay soils retain water but may impede root penetration, necessitating mechanical loosening.

Soil pH and Nutrient Status

The pH of the soil influences nutrient availability to plants. Ornamental plants generally prefer slightly acidic to neutral soils (pH 6.0 to 7.0). Testing soil pH and nutrient levels can be conducted through county agriculture offices or private labs. For instance, at a county government office nursery in Nakuru, soil testing enabled adjustment of lime application to correct acidity, improving plant growth.

Topography and Drainage

The slope and drainage patterns of the site affect water accumulation and erosion risk. Flat or gently sloping land with good drainage is ideal for most ornamentals. Sites prone to waterlogging, such as low-lying areas near rivers in Kisumu, require drainage improvements to prevent root rot.

Presence of Weeds and Previous Land Use

Assessing weed pressure and the history of the land helps in planning weed control and soil remediation. Land previously used for crops may have residual herbicides or nutrient depletion that need addressing before planting ornamentals.

Accessibility and Resource Availability

Proximity to water sources and ease of access for labor and machinery influence the feasibility of land preparation and ongoing maintenance. A hotel landscaping project in Nairobi prioritized sites close to reliable water supply to reduce irrigation costs.

2.1.2 Clearing and Weed Control

Clearing the land of unwanted vegetation and debris is essential to reduce competition for resources and minimize pest habitats.

Manual and Mechanical Clearing

Manual clearing involves cutting and removing shrubs and grasses using hand tools like machetes and hoes, suitable for small-scale projects such as school compound beautification. Mechanical clearing using tractors or brush cutters is efficient for large nurseries or estates but requires investment and skilled operators.

Removal of Debris and Stones

Stones, roots, and other debris can hinder tillage and root growth. Removing these materials improves soil tilth and facilitates planting. For example, a cooperative farm near Eldoret removed stones manually before establishing a rose nursery to improve planting bed quality.

Application of Herbicides

Selective herbicides may be applied to suppress persistent perennial weeds. In urban settings, care must be taken to use environmentally safe herbicides to avoid contaminating water sources. The use of glyphosate around a county government office flower garden was carefully timed to avoid damage to desirable plants.

Timing of Clearing Operations

Clearing should be done well before planting to allow decomposing organic matter to improve soil structure. In Nairobi’s university botanical gardens, clearing was scheduled two months prior to planting to optimize soil conditions.

2.1.3 Soil Cultivation and Conditioning

After clearing, soil cultivation prepares the seedbed or planting area by loosening soil, incorporating amendments, and improving aeration.

Ploughing and Tilling

Primary tillage using a plough breaks compacted soil layers, while secondary tillage via harrowing or rotavating refines the soil texture. For ornamental plants like hibiscus, loosening the soil to a depth of 30-45 cm promotes deep root growth.

Incorporation of Organic Matter

Adding compost, manure, or other organic materials enhances soil fertility and moisture retention. In a county hospital garden in Kisii, farmyard manure was incorporated during tillage to improve soil nutrient content and structure.

Soil Levelling and Bed Formation

Creating level beds or raised beds ensures uniform water distribution and reduces erosion risks. Raised beds are beneficial in poorly drained soils, such as those in the Lake Victoria basin, to improve aeration and root health.

Soil Moisture Management

Land preparation should consider soil moisture content to avoid working overly wet or dry soils, which can lead to compaction or poor seedbed conditions. A retail flower nursery in Nakuru monitored soil moisture before tillage to optimize soil friability.

2.1.4 Soil Fertilization and Amendment

Proper fertilization and amendment correct nutrient deficiencies and improve soil conditions tailored to ornamental plant needs.

Basal Fertilizer Application

Applying basal fertilizers before planting ensures nutrients are readily available during early growth. A hotel landscaping project in Mombasa applied balanced NPK fertilizers (e.g., 20:10:10) during land preparation to support ornamental shrubs.

Liming Acidic Soils

Liming raises soil pH in acidic soils, improving nutrient availability and microbial activity. For example, lime was applied in a university arboretum in Kericho to counteract heavy soil acidity.

Use of Soil Amendments

Materials such as gypsum improve soil structure in sodic soils, while biochar enhances nutrient retention. A cooperative in Meru used gypsum to reclaim compacted soils before establishing ornamental hedges.

Incorporation of Micronutrients

Micronutrients like iron, zinc, and manganese are vital for plant health but often deficient in Kenyan soils. Foliar sprays or soil incorporation during land preparation can correct deficiencies.

Timing and Methods of Application

Fertilizers and amendments should be evenly distributed and incorporated into the soil during tillage to maximize effectiveness and minimize nutrient losses.

Chapter Summary

This chapter covers the essential steps involved in establishing ornamental plants, starting with the preparation of the land, which includes clearing, ploughing, and leveling to create a suitable growing environment. It proceeds to the planting of seedlings, emphasizing proper spacing, depth, and handling to ensure healthy establishment. Field management practices are discussed next, focusing on watering, weeding, pest control, and fertilization to maintain plant health and promote growth. The chapter also details how to carry out land preparation using various methods tailored to different soil types and conditions. It then guides the practical steps for planting seedlings effectively to maximize survival and growth rates. Finally, it addresses the execution of field management practices, highlighting timely interventions and monitoring to sustain ornamental plant development throughout the growing season.