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THECOMMERCIAL GREENHOUSEGROWER • JULY 2017
• NEWS
LATEST
NEWS
Pot herbs as good in
newmedia as in peat,
research finds
Prototypepeat-reduced andpeat-free growingmedia
haveproducedpot herbs to as good aquality as those
inpeat in trials undertaken as part of a five-year project
aiming to reduce the industry’s reliance onpeat or any
particular alternative.
Theproject, which started in 2015, is fundedbyDefra
andAHDBHorticulture and is supportedby four growing
mediamanufacturerswho areproject partners –Bord na
Mona, Bulrush, ICL andSinclairPro. The goal is amodel
that canpredict theperformance of growingmediablends
basedon analyses of key characteristics of individual
ingredients. It covers a range of crops and sectors
including vegetableplant propagation, substrate-grown
strawberries, beddingplants andnursery stock aswell as
pot herbs. Themodel will helpmanufacturers design new
productswith knownperformance characteristics and at
prices competitivewithpeat-basedmedia.
“We characterised 76 rawmaterials in the first year,”
ADAS headof horticulture andproject leader Barry
Mulholland toldgrowers at anAHDBworkshop inWest
Sussex in June.
“From the resultswedevelopedprototypemedia
combining up to four ingredients in various proportions
that ourmodel predictedwouldhave a similar
performance topeat and thesewere tested in trials at
ADASBoxworth last year.
“We also ran trials onnurseries under commercial
conditions using commercially availablepeat-free and
peat-reducedmedia suppliedby our project partners.”
In thepot herb trial at Boxworth threeprototypemedia
were comparedwithpeat, andwith ablenddesigned to
performpoorly as a check of themodel’s predictive ability.
Summer- and autumn-sown coriander, chive and thyme
were grown in9cmpots on ebb and floodbencheswith
two irrigation and nutrition treatments for eachblend.
“Overall theperformance of each species in theprototype
blendswas as good as inpeat even in the lownitrogen
regime,” saidADAS’sSoniaNewman.
As a result of the trial, threeprototypepeat-freeblends
arebeing tested this year on spring and autumn crops of
basil, chive andplug-grown rosemary under commercial
conditions at LincolnshireHerbs.
Commercially availablepeat-reduced andpeat-free
mediaprovidedby theproject partnerswere testedon
spring, summer and autumn crops of basil, coriander and
parsley at Vitacress’s pot herbnursery at Runcton,West
Sussex in2016, under the nursery’s standard irrigation
andnutrition regime.
“For each species and for each sowing therewas very
littledifference ingermination and littledifference in
root development between any of themedia, including
the nursery’s standardpeat-basedmedium used for
comparison,” saidADAS horticulture consultant
ChloeWhiteside.
“Usingpeat-reducedmediadidnot appear to have a
significant impact onmarketability. Thepeat-freeblends
hadmore effect on height andweight of theplants.”
Vitacress researchmanager SimonBudge said that the
company hadbeen investigating alternativemedia for at
least 10 years. “Customer pressure to reducepeat use
is creepingback so it is important tounderstand how
these substrateswork andwe’d certainly agreewith the
principle of not being reliant on a single growingmedia
ingredient,” he said.
He added that, irrigationmanagement andpossible
increaseddisease susceptibility, for example tobasil
mildew, were areas for further investigation.
DrMulholland said the next generationof prototype
blendswould include analysis to see if therewere any
aspects of performance that couldbe improved compared
withpeat. “If we just aim to copy peat wemay bemissing
something that’s better,” he said.
“But it’sworth saying that there are already some
fantasticpeat-free andpeat-reducedproducts out there
that work verywell.”
Part of themedia trial onpot herbs at Vitacress.
