When it comes to choosing the right hydroponic growing media, there are many factors to consider that are directly related to its physical characteristics.
By Christine Brown-Paul
Most of the success of any hydroponic plant production system depends on root growth and development. It follows that when it comes to choosing the right hydroponic growing media, there are many factors to consider that are directly related to its physical characteristics.
According to horticultural experts, some of the most important factors include:
• Good ratio between water holding capacity and air filled porosity
• Low bulk density and high porosity
• Good drainage
• High steer-ability—this relates to how easy it is for the grower to maintain its crop in balance between vegetative and reproductive growth
• High uniformity of particle size distribution
• Chemically inert
• Free of impurities
• Easy disposal
• Local availability.
The power of Perlite
According to many growers, one media that ticks all the boxes is Perlite, with the fastest growing application for the product in the horticultural field being hydroponics.
Perlite exhibits a unique capillary action in that nutrient-rich water can be drawn up from a reservoir through a fine Perlite growing media at the rate that is required by a plant or the grower. As a result, plants grown hydroponically with Perlite do not suffer from over-watering or under-watering.
So what exactly is Perlite?
“Perlite is a lightweight, sterile and porous glass bubble,” says Louis Raper from Exfoliators, the company, which produces the media.
“Through a process of rapid heating (950 degrees Celsius), trapped moisture boils out of the particle causing expansion by approximately 15 to 20 times its original size.
“Perlite is then graded into specific particle sizes to provide specific benefits to a grower, greater water and nutrient holding capacity from finer particles, or greater drainage from larger particles,” Louis explains.
A family-owned and operated company started in 1959, Exfoliators is today one of Australia’s largest producers of Premium Perlite, Premium Vermiculite and Passive Fire Protection products.
“In the early years of Exfoliators, we simply manufactured vermiculite for the horticulture market, but since 1998 we have expanded into many areas of industries, servicing our customers with product throughout Australia, New Zealand and South East Asia,” he says.
“Exfoliators prides itself upon being a world-class producer of the products, with our key focus surrounding product quality, consistency and high service level. The horticulture and hydroponic industries have been a major part of Exfoliator’s operations today.”
Accredited to ISO 9001, ISO 14001 and AS/NZ 4801, Exfoliators and its products are certified as inputs by Australian Organic.
“Given that Perlite is a sterile and pH neutral media, growers are starting from a level base with no variables to compete with,” Louis says.
“The range of Perlite grades offered by Exfoliators allows growers to be very specific about their media choice. It provides the grower flexibility to operate in varying levels of automation, system design, climate and even how they may look to steer a particular crop or variety.”
According to Louis, some growers have found that shelf-life is improved throughout their supply chain, thanks to greater moisture and nutrient retention within the Perlite particle.
“Because Perlite is a porous particle, moisture and nutrients are retained within each individual particle, rather than just on the surface area between particles,” he says.
“Exfoliators offer Grow Bags and also loose media for filling of different sized pots, trays or cups, allowing for cost-effective media transitioning within an established system.
“One grower has shown that the transition from Perlite Grow Bags to Grow Pots was easily made, without needing a change in the established infrastructure,” Louis says.
Through careful raw material selection and grading, from the one initial media purchase, the grower and Exfoliators have now seen strong, replicable yields and no reduction in quality for the three consecutively grown tomato crops from the single media purchase.
“This translates to a media cost reduction of 67%, with further gains achieved through labour cost reductions saved from no growing media change out,” Louis says.
“This represents a no mean feat and was achieved through Perlite’s capacity to be re-sterilised easily and to be free of nutrient build up within the Perlite media.
“Our grower base utilising and benefiting from Perlite continues to grow—Exfoliators has supported this growth, which now extends throughout the Asia-Pacific,” he says.
“We’re finding that more and more growers are chasing a high quality and consistent producer of Premium Perlite products. As our base grows, Exfoliators continues to strive to develop new and innovative products, which support the Perlite Growing System.”
From seed to sale
One of the many grower operations using Perlite is B&B Basil, a family business located in Bendigo, Victoria. Microherbs and microgreens have long been the main area of focus for the company and demand for the product continues to grow nationally and internationally.
“We produce around 30,000 units each week for the local markets and for export,” says B&B’s George Bobin.
“We have around 2000 square metres under cover and offer a range of different products, including herbs, lettuce, watercress, carrots, celery and mint as microgreens.
“Microgreens are the stage between sprouts and baby leaves, which people use as a garnish on meals to add flavour,” he says.
“There is a big demand from chefs and providores for the product, particularly in overseas markets like Singapore, where we can’t seem to supply enough.”
B&B Basil began in 2000. After noticing a lack of locally grown herb products at the Melbourne fruit and vegetable market, father and daughter team, George Bobin and Susie Young, decided it was time to begin something new.
“We began growing large hydroponic basil in pots, which became very popular so it all started from there,” George recalls.
By experimenting with the seeding and growing process, George and Susie saw an increase in the flavour, quality and shelf-life of their products. One of these many innovations included growing larger amounts of seeds from the single pot, allowing the product to have a greater shelf-life and providing the consumer with a larger size product.
“By 2004, Susie and I decided it was time to move to a larger facility and hire some extra hands to help meet the growing demand. With the move to Rowena Street in East Bendigo we built two small greenhouses with a seeding and potting area. With more space, we noticed a greater market for microherbs, expanding to grow a greater variety of microherbs from start to finish on the single site,” he says.
“We then built a larger seeding and potting shed and took on new staff to handle the increased workload. By this stage, the products were being purchased not only at the Melbourne fruit and vegetable markets but also across Australia.”
Some of the newest innovations being adopted include environmentally friendly methods of agriculture, solar power, alternative ways to heat the greenhouses and a lightweight synthetic soil for export.
In terms of fertigation, B& B Basil uses the NFT system.
“We don’t use top spraying, however, because of the density of the seedlings,” George says.
“We use a potting mix consisting of pinebark, peat moss and cocopeat, but in winter this tends to become overly wet, so we use Perlite to open the mix up.
“Louis from Exfoliators has worked with us to develop specially made Perlite grade exclusively for B&B Basil,” George says.
“This is used in punnets, which measure 8 x 8 x 2 cm deep and are filled with Perlite, seeded with microherbs and then germinated.
“Once the plant is grown, then the whole punnet is enclosed in a strawberry container and sealed ready for export,” he explains.
“We’re very happy with the Perlite media and it has given us good results.
“We have a multi-tier set-up for the plants in a flood drain system and have LED lighting, and we’re getting very good outcomes together with using Perlite,” George says.
“We’ve tried and tested it and have grown thyme in a conventional system, which only delivered around 50% of saleable product.
“Using the flood and drain system and using Perlite has delivered exceptional results, with close to 100% saleable yield,” he says.
George says his micro-herbs are “living” when they are exported and were never more than 10 to 14 days old so they avoided losing freshness.
IPM is used only on the operation’s edible flowers.
“We grow edible flowers like nasturtiums, violas and other plants on protective areas so we will use IPM here, but because of the short time the microgreens are in situ, it isn’t needed there,” he says.
“All in all, it is only seven to 21 days from seed to sale,” he says.
Today, B&B’s business is burgeoning and now employs around 30 staff.
Recently, George travelled to China to look at the potential of starting a herb farm in the country’s southern Guangzhou region. He has looked at suitable farm land in China. If one farm goes well, George said he would consider starting a few more.
“There are 25 million people on the Guangzhou region, which is basically the population of Australia,” he said, adding that a China-based farm would reduce the challenges he faced in flying herbs to his existing import destinations—Hong Kong, Bali, Bangkok, Dubai and Singapore.
“My theory is that you produce in an area for the area, mainly because of the fragility of the product.”
According to George, one of the biggest challenges facing the company is increasing competition in the market.
“This is why we’re looking at overseas markets and perhaps even starting farms over there,” he says.
“Another challenge is the rising price of energy. If we can reduce our heat source and utilise any waster product, all the better. Ω
PH&G October 2014 / Issue 148