Page 18 - Simply Vegetables Summer 2022

Branded Peat and Peat-Free Substrates –
Comparison of Yields
Data from ongoing study of yields from different substrates growing Phaseolus Coccineus in Pots
Trial at Waltham St Lawrence
1 May 2021–24 October 2021
1. Work thus far
AIM
Our aim has been to find a way for house- holds without a garden to grow satisfactory crops of climbing runner beans (comparable to those from plants in open ground*), – dwarf runners’ yields at 40% of yields from climbers being too low for the purpose.
VARIETY GROWN
Benchmaster F1 were chosen, on advice (2) and after comparing crops with those from Wisley Magic F1 were found virtually identical.
DESIGN OF FRAME
We settled on a loop frame design fitting in a space as small as a balcony, height of plants being lowered by curbing of apical dominance, and the width limited to 25cm – the diameter of a 10-litre pot.
Yields were compared from plants growing for different distances and results used to determine the length of the horizontal and the verticals in the frame. We settled on a frame offering a total growing distance of 180cm from root to trimmed end.
Apart from growing media used all plants were cultivated identically.
Plants were grown in sets of six.
GROWING MEDIA
Peat compost
Wickes multipurpose peat compost with John Innes 3® (Which? Garden ‘Best Buy’ ) was used every year; in 2019, when used with liquid fertiliser (Tomorite®), this gave the highest yield – 834.3g mean yield
per plant. Yields using a Maxicrop® liquid fertiliser were slightly less (6.8%).
2019 was the first year we included
a peat- free substrate as a comparator. Growlite® Coir with Tomorite® produced 765.3g
Moving to peat-free
In 2020 we continued with both Wickes peat/John Innes 3® and Growlite® Coir/ Tomorite®, and added a second peat free, Miracle Gro® all-purpose premium (containing some blue fertiliser tablets) with Tomorite®
We concluded that satisfactory yields
were achievable with particular brands of peat-free substrate when used with a liquid fertiliser formulated as Tomorite®.
It was decided to move to peat-free only in the next trial and compare yields from more brands.
2. 2021 Trial
Changes to 2020 Scheme of trial
When the growing media products used thus far were used by a focus group, they commented that novice growers might react negatively to the use of Growlite® and Tomorite®. Growlite® requires the production of a large quantity of substrate (60 litres) mixing a coir block with water.
Tomorite® requires a large amount of water per two plants (One gallon).
Neither was used in the 2021 trial, the fertilisers used (where applicable) being branded slow-release tablets.
Scheme of the trial
Below are: (a) the scheme of the trial (b) captioned photograph.
*On advice (1) we accepted following values for yields per plant:
Over 1,000g 700–1,000g
500 – 700g Below 500
Exceptional
(approx. 50–60 pods) Good
Satisfactory Unsatisfactory
Mean yields per plant:
Wickes John Innes 3®, Tomorite®: Growlite® Coir, Tomorite®:
Miracle Gro® peat-free, Tomorite®:
599.0g 835.2g 777.5g
18 Simply Vegetables
TONY BRUNKETT FNVS