Fertilisers for ornamentals

Manufacturers are developing an ever-increasing range of products to help growers, Sally Drury reports

Top dressing: enables controlled-release fertiliser to be applied to crops on nurseries - image; Everris
Top dressing: enables controlled-release fertiliser to be applied to crops on nurseries - image; Everris

Has there ever been so much choice in terms of plant nutrition? There are plenty of controlled-release products, water-soluble products, foliar feeds, biostimulants - it is hard to know where to start.

Further complications arise when you want to consider changing your growing media or your water supply, especially if you are thinking about using peat-reduced growing media and harvesting water for reuse on the nursery.

Testing climate

The unpredictable nature of the British climate is always testing to growers and changing weather patterns are thought to be leading some to reconsider the use of controlled-release fertilisers (CRFs).

At William Sinclair Horticulture, a trend has been noticed for some growers to reduce the amount of CRFs in their growing media and supplement with a soluble fertiliser, such as the company's Sangral, to give more control over growth and crop quality. The Sincrocell range of CRFs, which continues to provide nutrients in growing media when required, is also proving popular.

"Sincron is a very popular top dressing for overwintered plants, providing both fastand slow-acting nutrients with the need for re-potting," explains technical manager Andrea Marshall. "Sincron releases over a twoto three-month period for balanced growth and good leaf colour."

Marshall also recognises that growers understand the importance of testing water quality on a regular basis, especially when using borehole water, and are adapting their feeding regimes accordingly.

Ultimately, for both fertiliser manufacturers and growers, the need remains to respond quickly to changes in production. As a direct result of the increase in rainwater harvesting, the volume of soft water used on UK nurseries has risen dramatically - and soft water is very low in dissolved nutrients.

While water-soluble fertilisers (WSFs) will add most nutrients, others such as calcium and magnesium tend to be low or lacking altogether. Added to this is the fact that the reduction in atmospheric pollution has resulted in falling sulphur levels. Sulphates have been used to supply sulphur in WSFs but tended to contribute to EC and compete with other nutrients.

Everris has developed Peters Excel CalMag Grower with Organic-S and Peters Excel CalMag Finisher with Organic-S to deliver single- product solutions to complete plant nutrition in soft water.

The Grower formulation (14-6-14 +6.5CaO + 2.5MgO + TE) is designed to promote better and faster rooting, leading to enhanced plant quality. In trials in Germany, it was seen to improve leaf colour, fresh weight and flower number in pelargoniums. Further trials with poinsettias led to better colour, higher fresh weight, a better root system and a more compact plant. The Finisher formulation with Organic-S (12-6-20 + 6CaO + 2MgO + TE) is intended as a follow-up feed.

Everris has also extended its Universol portfolio with new hard water and soft water options to make a complete range for all growing circumstances and water qualities.

Core nutrition

Nursery stock production relies on CRFs to provide core nutrition, either incorporated into the growing media or with supplementary feeding in the second season by top dressing. WSFs are generally used to treat any deficiencies or to tweak final quality.

Precision of fertiliser release is important, and even more so with current environmental trends as well as the need to be careful with the pennies. Everris points out that its market-leading Osmocote range has become more sophisticated, linking fertiliser-release patterns to plant needs through not just a range of product longevities but also by dual coating.

"Osmocote Exact Protect is designed for autumn and winter potting while Osmocote Exact Hi. End is for crops with high nutritional needs late in the season," says Everris technical manager Andrew Wilson. "Due to the dual coating of 25 per cent of the granules, Hi.End products have a slow-release pattern to start with, which then increases during the season as the growing plant's nutritional needs increase."

He continues: "For nursery stock, rather than simply using a 12- to 14-month CRF, employing our AngelaWeb precision nutrition software tool we can look at the exact needs of the species and, taking into account other factors such as weather data, produce a nutrition programme to fit its exact needs."

Designed by the experts at Everris, AngelaWeb 2.0 is said to take precision nutrition to the next level. Containing more than 900 individual recommendations, tailored to specific ornamental as well as some fruit crops, the software tool uses information about crop type, variety, growing media and growth phase to display the plant's specific nutritional demands.

By inputting information on water source and how it is applied, and selecting the fertiliser products of choice, the programme calculates a regime tailored to the exact needs of that crop, helping to maximise yields, increase productivity, reduce nutrient wastage and save management time.

Rapid assessments

"AngelaWeb 2.0 simply and quickly assesses whether the correct amount of nutrients is being applied to the crop and ensures that inputs are not being needlessly wasted," Wilson explains. "By employing this software tool it is possible to quickly assess whether critical set points are being achieved in the nutrition programme."

Then there is the question of foliar feeds and biostimulants. You might think they are just an additional cost or something to try when all else fails. Or you might think there are so many products offered that you simply would not know which one to use. Increasingly evidence is showing that there are benefits to be had in terms of quality and yield. Perhaps they are worth further investigation - after all, as with human health, prevention is often better than cure.

The ornamental plant trade has always relied on granular, soluble and controlled-release NPK to supply virtually all plant nutrients. But now some growers are finding that NPK alone does not always give plants the optimal quality and yield.

"The biggest problem is that many growers only consider foliar feeds and biostimulants after the damage has been done," says OMEX Horticulture sales manager Richard Cameron. He often gets calls from growers asking him to take a look at a sick crop of nursery plants. "I sometimes feel like a doctor on call," he adds. "If only they had spoken to me sooner, I could have put the plants on the right diet to start with."

The trade has always relied on the same basic products but technology and the formulation and understanding of how foliars work has moved forward, and with proven results. "The key difference to using a foliar is in the way the nutrition is delivered to the plant - through the leaves," says Cameron.

"This delivery mechanism is especially useful when roots or soils don't allow nutrition to enter the plant from the bottom up, particularly in young plants whose roots are poorly established and are not yet effective in seeking out food and water."

Kelpak Bio Stimulant is one example of a product that is proving very useful in propagation or transplant stages, he adds. It is an auxin-based seaweed concentrate differing to most seaweed products in that it contains cytokinins. The auxins stimulate the plant's own system to encourage good healthy and fibrous roots, which will in turn support a strong plant up top.

Cameron says one large ornamental grower in Lancashire used OMEX foliars for years but now, instead of using them when a problem occurs, he uses them as part of an integrated growing regime to give an extra boost without elongation, helping to keep plants compact but maximising colour.

Whatever foliar product is used, OMEX recommends adding an adjuvant to improve uptake. "Typical salt formulations in most foliar nutrients have poor wetting and spreading characteristics, little better than water in many cases," explains Cameron. "Including a wetter like our OMEX NA13 to the final spray solution helps with improved adhesion, deposition and penetration of the nutrients into the leaf surface."

But it should be remembered that compatibility, different rates and water volumes need careful calculation, so it is always wise to check with the supplier for advice.

Osmocote Bloom: bedding plant feed

Traditionally the bedding plant industry has been reliant on programmes that employ a base fertiliser followed by water-soluble. Everris technical manager Andrew Wilson says this can be highly wasteful, with up to three times as much fertiliser applied compared to controlled-release fertilisers (CRFs).

Water-soluble products also necessitate applying a lot of water, ultimately encouraging growth. In a bid to produce compact bedding plants with plenty of flowers, growers therefore tend to use growth regulators, although fewer products are now available. Everris believes Osmocote Bloom is an answer.

"Osmocote Bloom is unique in that it is a CRF specifically designed for bedding production," says Wilson. "It has a longevity of 10-12 weeks at 21 degsC. In nursery terms for spring potting this equates to three-to-four months at 16 degsC. These mini granules are ideal for use in small volumes of growing media and it is competitively priced."

Mixed into the growing media, Osmocote Bloom is said to not only save time and reduce labour costs but also enables the crop to be kept drier, giving growers greater control. The 12-7-18 analysis is designed to give compact growth and flowering. The controlled release means the nutrients are not all there at the start, helping to minimise root disease as well as keeping the EC of the growing media lower. Shelf life is also enhanced, maintaining quality in the supply chain and ultimately with the consumer.

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