How to Choose Woodfiber as Peat Alternative for Ornamental Plants

Woodfibre Has Specific Physical and Chemical Properties

Peat has long been a highly reliable material for growing plants. However, due to evolving legislation and changing perceptions, its use is gradually being reduced. Comparing peat and its alternatives based on their respective properties and performances, can be misleading. Materials such as woodfibre require management approaches tailored to their own physical and chemical characteristics, which may differ from those associated with traditional peat-based mixes. For example, peat-free growing media generally require closer attention to both nutrition and water management. These substrates typically have lower buffering capacity and reduced nutrient retention compared to peat—two key properties that influence crop stability. As a result, the distinct characteristics of non-peat materials lead to growing media that require adjusted cultural practices.

Know Your Woodfibre Type to Choose the Best Cultural Practices

A general overview on woodfiber as a peat subtitute or as an ingredient of peat-reduced substrates can be found on our dedicated article. Now let’s focus what is important from a grower’s perspective when shifting to woodfiber. ICL suggests to always begin by understanding the specific type of woodfibre included in the growing media.  Being aware of its characteristics helps support consistent crop performance.

• It is important to identify the type of woodfibre used in the mix and understand its specific requirements
• Crop management strategies should not rely solely on the experiences of other growers, as results can vary depending on the substrate composition
• Production guidelines and recommendations provided by the growing media supplier are a valuable reference point

Key Considerations When Growing Ornamental Plants with Woodfibre

When woodfibre is included in the growing media, several aspects of crop management require attention:

Nutrition

Woodfibre can be an effective component for reducing peat usage while maintaining crop performance, provided it is evenly incorporated into the mix and supported by an appropriate nitrogen strategy. One of the main challenges associated with woodfibre is nitrogen immobilisation (N-fixation). To support nutrient availability throughout the crop cycle, the following ICL solutions can be considered:

• Cal-BOOST: Designed for peat-reduced and peat-free substrates, it supports ornamental plant production in situations of nitrogen drawdown and when additional calcium and magnesium are required
• Osmocote N: Provides a sustained supply of nitrogen and some potassium, suitable for longer-term crops such as nursery stock
• Osmoform High N: A slow-release fertilizer suited to short-cycle crops, including bedding and pot plants

As with any growing media, it is important to monitor nutrient availability over time. Peat-reduced substrates typically have lower buffering capacity, making it essential to adjust fertigation or topdressing once the initial nutrient charge declines.

Physical Composition

Maintaining the correct air-filled porosity (AFP) is critical for healthy root development. Woodfibre can contribute positively to improving aeration within the growing medium. However, balance is important. High proportions of a single peat alternative may lead to structural instability over time. For example, substrates with high woodfibre content may experience shrinkage or slumping, particularly in longer crop cycles. Crop duration should therefore be considered when designing the mix.

Moisture Management

Water management practices should be adapted to peat-reduced growing media, as their behaviour differs from that of peat-only mixes. Dig deeper on this subject by reading our article on moisture measurement on peat-based substrates vs peat alternatives. H2Gro, a blend of surfactants incorporated into growing media, is designed to improve water distribution, enhance rewetting, and optimise water holding capacity. By supporting more uniform moisture levels, it can contribute to more efficient water use and reduced waste. H2Gro can be easily integrated into a wide range of growing media, including those containing woodfibre.

pH Management

pH levels should be closely monitored, particularly during the first weeks of cultivation. New substrates may exhibit fluctuations due to their specific buffering characteristics, like explained on this article on how pH develops and behaves in new substrates. Growers using peat-reduced mixes often observe greater pH variability compared to traditional peat media. Typically, pH may rise initially and then decrease during the early stages of crop development. If not carefully managed, these fluctuations can affect root growth, nutrient availability, and overall plant performance. Regular monitoring and timely adjustments are therefore recommended.

Conclusion

With appropriate nutrition, water management, and pH control, woodfibre can be successfully integrated into high-performing growing media. Before making a full transition to new growing mixes and for tailored recommendations and support in developing a suitable nutrition strategy, contact your regional technical advisor via your country’s website or the contact form available on the bottom of this page.