Feeding drama queens | Osberton Nurseries

With two distinctly different water sources, specialist ericaceous plant producer Osberton Nurseries deploys two tailored feed programmes to optimise the quality of its dramatic and colourful crops.   

Operating from a 20ha site on the picturesque Osberton Grange Estate, near Worksop, Osberton produce quality Rhododendrons, Camellias and Azaleas supplying customers nationwide with a dramatic, colourful and exciting range of these ericaceous show stealers.   

“We produce 30 hybrid Rhododendron cultivars, 20 Camellia and 45 Azaleas meticulously selected and trialled to work well in UK gardens,” says Graham Newbury – Technical manager.  “We’re continually trialling and assessing new varieties to add to our portfolio, which offers customers a range of colours and 6-7 of each flower type.”  

Rhododendrons predominate with over 250,000 container grown dwarf, evergreen, deciduous and Yakushimanum hybrid varieties grown in the field – including several of the large-flowered ‘drama queens’. In the site’s 1ha glasshouse, the team produce 47,000 Camellias and 40,000 evergreen Azaleas.  The plants are individually hand pruned and on leaving the nursery are well established, fully hardy and generally at least three years old.  

Osberton’s product range also includes deciduous Azaleas, Daphne, blueberries and heathers.   

Propagation  

While propagating inhouse from cuttings, the nursery also buys in liners from Poland and Belgium to pot and grow on. Plants are potted into a peat-reduced growing media containing Osmocote High K, Osmocote Low Start and Micromax Premium.  

“Ericaceous crops often have two flushes of growth and are iron hungry,” says Carl Mason – ICL technical area sales manager.  “Micromax Premium contains chelated iron which helps make this important micronutrient available throughout the growing season.”    

Long term crops, when the Osmocote High K has run out, Graham and his team are heavily reliant on water solubles during the growing season.   

Hard borehole water

“With water solubles to some extent you can force feed the plant to do what you want,” says Graham. “At this site we rely on borehole water to irrigate the field-grown stock.”  

In the past the team were reliant on standard Universol range of water soluble products.   While generally happy with crop nutrition, in 2021 Graham raised the issue of limescale build up in the irrigation lines.     

Detailed water analysis

Carl took water samples at the nursery and sent them away for a detailed laboratory analysis.  

“Water with high bicarbonate levels can cause precipitation of nutrients in the irrigation system – leading to limescale blockages and reduced nutrient efficiency,” explains Carl.  “The water analysis results confirmed the hardness of the water.” 

Working with ICL’s Technical Manager Andrew Wilson, the results were fed in to AngelaWeb 3.0 – ICL’s precision nutrition software programme.  

“Together with information on the crops being grown, and an analysis of the growing media, AngelaWeb recommended an upgrade to Universol Hard Water feeds,” says Carl.  “These specialist feeds are designed to improve the quality of the water by taking out bicarbonates.”   

At the start of the growing season, Osberton now rely on Universol Hard Water 211 (23-10-10+2MgO+TE).  “With an N:K ratio of 2:1 it is ideal for plants requiring high amounts of Nitrogen during the early growth stage and has a full trace element package,” says Carl. “The 211 formulation feeds the container grown field crops up to July.    

From August to the end of the growing season, in October, Graham and his team switch to Universal Hard Water 225 (11-10-28+2MgO+TE).  “This promotes compact growth and is ideal for hardening plants off plants while acidifying irrigation water and neutralising bicarbonates,” explains Carl.  At the end of the season before the outdoor irrigation is switched off, Osberton now flush through the lines with PeKacid.   

Graham is pleased with the results. “Switching to these Hard Water Universol products, while almost eliminating the limescale build up in the pipes, we now have a better quality crop – darker green foliage and bud set in autumn has improved,” he says. 

Soft rainwater

In contrast to the hard borehole water, the unheated glasshouse grown crops and propagation unit are supplied with soft rainwater harvested from the rooves.   

Having input the results of the laboratory analysis of the soft water- AngelaWeb 3.0 recommended switching the feeding programme using rainwater to the Universol Soft Water Range.   Graham and his team now rely on Universol Soft Water 312R (18-7-12+6CaO+2MgO+TE).   

“With a N:K ratio of 3:2 and high calcium, it is ideal to encourage early crop growth and give optimum leaf colour,” concludes Carl.