By Ruth Vaughan, CropNuts Technical Director

European flower importers are pushing for their suppliers to be able to demonstrate sustainable policies and practices. The pressure is on..

In order to continue to be economically sustainable one must comply with the market demands and trends or find a new market.
From a horticultural view we must look at our farming practices and monitor and adjust them in order to make sure that we maintain or improve the soil and the environment, and not degrade it.  This not only complies with the market demands but also comes with economic and social gain, as a fertile soil is a productive soil, and clean water is cheaper and better to use.
At the onset of any farming project one should do a feasibility study on the farm including soil mapping, soil depth, soil type, contours, climate, soil and water testing.  A good farm design with proper flow diagrams is essential for a well-run farm.  Farms that pop up with-out planning are a nightmare to run and tend to end up a chaotic mess.
Sustainability chart

Soil Grown Flowers

For soil grown flowers one should take a complete soil analysis before soil preparation and planting, in order that the correct soil correction products (lime / gypsum / phosphorous / organic matter) can be added into the soil and mixed in at depth in order to balance the soil EC / pH and soil structure and to maximize on fertilizer efficiency by the plants and minimize on pest control products.

Fertilizer and pesticide is monitored in most audits and over-use gains negative marks and reduced market access.  Check and treat for soil diseases and nematodes before planting.  These can be treated with a break crop of radish or with soil solarization before planting.

Effect of Soil pH

pH should be adjusted to be as close to pH 6.5 as possible.  pH has a big impact on the efficiency of the major fertilizers:- nitrogen, potassium and phosphorous, that you apply.  If, for example, your soil is working on a pH of 4.5, you would have to apply 4X more P, 3X more N and about 3X more K to get the same production.

That’s going to cost a lot of extra money and attract a lot unsustainability points, not to mention the lost stems.  NPK applied at the wrong soil pH gets locked up in the soil causing structural problems & lock up of other nutrients, or released into the environment.

Soil pH and NPK efficiency

Adjusting the soil pH to 6.5 has the additional benefit of making all the other nutrients more available as seen in the pH availability chart.

With all this in mind it shouldn’t be hard to convince you to do a soil test to adjust the pH, the cost of the soil test and the lime will be paid back many times over in reduced fertilizer use and better production.

Practical Tips

With all this in mind it shouldn’t be hard to convince you to do a soil test to adjust the pH, the cost of the soil test and the lime will be paid back many times over in reduced fertilizer use and better production.

While you have a growing crop in the field, I would recommend quarterly irrigation water analysis and 1:2 soil extract analysis in order to fine tune the fertilizer application according to the soil requirements and the water quality. For the best results this should be backed up by a leaf analysis to identify any minor nutrient deficiencies that can be quickly easily and cheaply rectified.

This ensures that you put in a ‘maintenance’ level of fertilizers – just what the crop needs for optimum growth and no extra.  Nematodes lurch under the soil, can’t be seen, and can also reduce fertilizer efficiency and plant growth.  They need to be monitored.

In Part 2 of this article we shall explore this topic further and discuss more practical tips on sustaining flower production over time. This includes managing flower irrigation water in the most efficient way possible.

Till next time,

Take care!

About Ruth


Ruth Vaughan is the Technical Director at Crop Nutrition Laboratory Services Ltd. (CROPNUTS). Ruth is also a contributing author to Kenya’s leading horticulture magazines such as the HortFresh JournalHortiNews and Floriculture. Ruth is a great believer in soil health, organic matter, biochar and carbon sequestration as a way to alleviate climate change and increase food security. Loves visiting farmers and seeing all the different farming methods