Establishing Peat-Free Crops Workshop – Industry Experiences of Peat-Free Media Adoption
A presentation exploring some of the issues being addressed as part of the transition to peat-free crop production.
Establishing crops in peat-free growing media
‘Summary of the HTA Grower Technical Workshop: ‘Tips for establishment of crops in peat-free growing media’
Crop establishment in peat-free growing media
Industry experience so far indicates that establishing crops in peat-free growing media needs more management time to ensure success. This is not surprising considering all the cultural factors that need attention and possible modification. Thinking through the entire process from growing media storage, young plant grading, the transplanting or potting process, and post-potting, active crop management, will all help to identify key control points.
The importance of rapid and uniform establishment
The uniform establishment of crops following potting or transplanting is one of the key factors which dictates the quality and evenness of the marketable crop. An even, well rooted crop is much easier to manage in terms of the inputs required, especially irrigation levels, but also nutrient application and growth control. Well rooted plants are also less prone to root pathogens, such as Pythium and Phytophthora, whose establishment and spread can be exacerbated by the overwatering of struggling plants within a variable crop (see image). Uniformity and speed of establishment will also determine the time taken to grow the crop to meet marketing targets, to minimise plant wastage, and to enable batch marketing of entire crops.
Growing media storage and moisture content
Growing media storage management is a challenge and should be addressed based on the time of year and storage conditions, using good stock control procedures. Moisture content and the distribution of moisture within professional media bales can be variable and this should be addressed at potting by adding more moisture via a tailor-made boom gantry on the interim hopper of the potting machine (see image) or via an in-line sprinkler system.
Priming young plant material
Uniformity of plant establishment doesn’t start at the transplanting or potting process, management of the young plant material beforehand (whether it is a plug, liner, or bare root) needs thought and attention. The creation of a robust health check and goods inwards procedure for bought in plant material is paramount. It can be difficult to maintain such procedures during busy periods, but early rejection of poor quality or uneven material means that the issue doesn’t become one for you to resolve post-potting. Ensure that plants are stood down and not left on trolleys for days or weeks, and that they are addressed in delivery order. If the crop cannot be potted immediately, or if the young plants look a little tired, then a regular low level liquid feed, high in phosphorus, at every irrigation will help to stimulate root activity prior to potting and minimise the period of plant inactivity post-potting.
It's also useful to ascertain what growing media the young plants have been grown in. Anecdotal evidence suggests that plants grown in a peat, or peat-based growing medium can take longer to establish when potted into a peat-free medium, compared with young plants grown in a peat-free medium going into a similar medium.
To encourage this attention to detail, offer training to staff members tasked with the role of inspecting plant material, and feedback comments or assessment scores to key propagating companies to build relationships and help ensure material is optimal at the time of delivery.
The transplanting or potting process
The success of any process is not simply about the numbers being pushed through the system on a daily basis, key parameters such as the moisture content of the potting medium, the amount of medium needed in each pot, potting depth and positioning of the young plant material (with or without any weed control mulch), and the immediate aftercare, in terms of in-line irrigation and onwards transportation around the nursery, need to be considered and actively managed. Some peat-free media are more prone to slumping than others, so judging both the level of medium required at potting and the depth of potting may take time to optimise.
Immediately post-potting, crops should be inspected for physical damage, ‘J’-rooting, presence of air pockets between the young plant and the fresh medium, and off-centre positioning of plants. Use of plug pusher plates is recommended rather than pulling young plant material out by hand which can damage stems and roots causing further stress to the plants.
Establishing the plants in the first two to three weeks
Regular wetting up of the top 4-5cm of medium is important. This helps to ensure that the young plant growing medium stays in contact with the fresh medium post-potting, drying back can result in the root ball pulling away from the fresh medium, leaving an air gap, and subsequent poor or delayed establishment (see image). The moisture content should be maintained at 45-60% in the top layer for two weeks, or until the plants have rooted into the fresh medium. Incorporation of wetting agents into the fresh medium will assist with even wetting up and uniform distribution of water within the medium. Any other factors that may lead to post-transplanting or potting shock, such as severe pruning, should be minimised.
Production considerations through to marketing
In the summer months, provision of overhead shade or the use of an anti-transparent spray, such as 2% Spraygard, can help to minimise the level of crop stress during periods of high light intensity and extreme temperature and speed up establishment.
Uniform overhead irrigation is key to prevent waterlogged or dry areas (especially around the bed edges) developing (see image). Conversely in the winter, look out for areas under leaking glass panes or guttering.
Avoid any electrical conductivity spikes in terms of nutrient release from high rates of incorporated base fertiliser and / or controlled release fertiliser; high conductivity levels can easily damage fine root hairs and lead to poor establishment, induced nutrient deficiencies, for example iron, and pathogen establishment.
The use of handheld probes will provide real time moisture and conductivity information, allowing early corrective actions to be undertaken, reducing the level of symptom expression within the crop.
The use of chemical or biological based biostimulants may have a role to play in establishment, especially if the growing conditions cannot be optimised. Ensure that crop protection programmes are also robust and up to date to prevent root and stem pathogens and opportunistic pathogens, like Botrytis, from establishing.
Presentations and Handout
Establishing Peat-Free Crops Workshop – Establishment of Crops in Peat-Free Growing Media – Grower Viewpoints
A presentation examining developments at Darby Nursery Stock.
Establishing Peat-Free Crops Workshop – Establishment of Crops in Peat-Free Growing Media – Scientific Viewpoints
A presentation covering key points from the RHS Peat-Free Fellowship.
Establishing Peat-Free Crops Workshop – Beneficial Soil Microbes
A presentation summarising the roles played by mycorrhizal fungi and plant growth promoting rhizobacteria.
Establishing Peat-Free Crops Workshop – Coir a Renewable and Environmentally Friendly Substrate
A presentation highlighting the production of coir and the potential to create bespoke media from different fractions.
Establishing Peat-Free Crops Workshop – Practical Advice and Tips for Improving Crop Establishment in Peat-Free Growing Media
A presentation summarising the management of young plant material and the aftercare of crops post-potting.
Establishing Peat-Free Crops Workshop – Handout
The handout collating all the presentations from the ‘Tips for establishment of crops in peat-free growing media’ workshop.