Issue 34: Western Lettuce

Issue 34
May/June – 1997
Story Title: Western Lettuce
Author: Roger Fox

Roger Fox visits two of the largest hydroponics lettuce enterprises supplying the Perth market.

he city of Perth has a population of 1.7 million, making it the third most populous city in Australia, after Sydney and Melbourne. It is also a highly popular destination for tourists, which swells the population and makes it an important market in food terms. Supplying Perth’s sizeable salad market are numerous hydroponic lettuce facilities, located in the hinterland of the city, mainly to the north and south.

Western Australia is a State which is used to being self sufficient. Geographically, it is thousands of kilometres from the more populous eastern states, and so its need to supply most of its own requirements goes back to its origins. Even now, with the marvels of ‘modern transport’, goods from the east coast often end up too expensive by the time they arrive in W.A. Obviously, in the case of perishable foods like salad vegetables, a self-sufficient supply is all important.

Typical of the newer breed of hydroponic lettuce producer in Western Australia, is Paul Maxwell, who established an NFT lettuce system about 5 years ago near the town of Baldivis, 20kms south of Perth. Paul’s streamlined production enterprise, Balhill Water Gardens, has carved a niche in the Perth market, and a large part of his fancy lettuce crop is bought directly by one of the large supermarket chains.

The 1 hectare (2.4 acre) site of the operation, situated on the lee side of a hill, first had to be cleared of the dense bushland which still surrounds it, before building could commence. Today the set-up comprises 111 NFT tables terraced down the side of a slope, the whole covered with a vast hail-net cover. The hail netting, which is quite commonly seen in this type of operation in WA, actually serves two purposes.

“Hail net works in two ways,” Paul explains. “It protects us against hail, but also serves as a wind break.

“If you want a windbreak around the sides, you’ve either got to have baffles all the way down the slope, or you put up a hail net cover, which is what we have done. The wind hits the top and bounces off.”

“Even with all this protection though, if we get a very windy day, the lettuce can still be lifted out of their channels.”

The hail netting has negligible shading effect, however. “They say it gives 10% shade, but in actual fact it increases the glare,” Paul explains. “So really, one compensates the other.”

In establishing Balhill Water Gardens, Paul literally carved the farm out of the bush. Old welding skills were revived to build the table supports -“someone had shown me how to weld about 30 years ago, so I thought if I could do it then, I could do it again. It took me a little while though!”

With the help of some contracted labour (and a trusty theodolite to get the slope of the tables right), the system was constructed. The growing tables measure 18 metres, with a drop of 30cm over their length, and each consists of 8 rectangular channels. The system is conventional NFT, with the recirculating nutrient supplied by two separate tanks – between 5000 and 10,000 litres are running through the channels at any one time.

Paul approached hydroponic production with the benefit of considerable plant growing experience. He had previously been a vegetable farmer (in soil) near the town of Albany, on Western Australia’s southern tip.

Originally born in Kenya, of English descent, Paul has lived and farmed in Western Australia for 35 years. More recently, Paul undertook a major expansion by taking out the lease on the vast Sumich lettuce growing operation at Mandogalup. This enterprise is the production arm of one of Western Australia’s largest produce companies, Sumich Pty Ltd. The move was an ambitious one, but ultimately two farms proved too difficult to run in tandem, and Paul recently decided to relinquish the lease to concentrate on his own operation.

In another move towards rationalising the work load, Paul no longer grows his own lettuce seedlings – these are now bought from a local seedling grower. The seedlings are three weeks old at purchase, and go first into the ‘nursery tables’, which are NFT tables with more closely spaced holes. They are grown here for a few days to a week, before transplanting into the main system. An advantage of this approach has been the freeing up of space in the general system, as Paul explains.

“When I did my own seedlings, they were 10 days in the seed trays and 10 days in the nursery tables before planting out. I’m finding now that I’m getting a bigger turnover by buying seedlings from the nurseries, because they are already 3 weeks old when they get here.” “On the other hand though, raising your own seedlings gives you just the right seedlings, just when you want them. But it is a lot of work.”

Paul grows a range of fancy lettuce and can request specific varieties at any time from his seedling supplier. He has seen the popularity of different varieties rise and fall over the years – at the moment red and green oakleaf types are very popular in the Perth market, but conversely, Buttercrunch has become less popular. Red and green coral varieties sell consistently and he is also growing a variety called ‘Blush’, as a replacement for Mignonette.

Water and Feeding
Like so many growers in Western Australia, Paul Maxwell relies on bore water to supply his system. Underground water is common in many parts of this state, making agricultural and horticultural enterprises feasible in places where rainfall would be vastly inadequate to support them. But bore water comes with its own set of challenges, mainly in the form of unwanted elements in its make-up.

“Here our main problem is calcium, so we have to put the water through a Reverse Osmosis unit. Salt is reasonably high, but not at serious levels – the water is still drinkable, for instance.”

The Reverse Osmosis Units are described by Paul as “expensive but effective”, and in fact he has recently had to purchase a second unit to keep up with the supply of water to be treated.

There are two nutrient tanks for the system – one of 12,000 litres and one of 20000 litres – both of which are only about a third full at any time. Attached to each nutrient tank is a computer which gives a constant read out of pH and EC. pH adjustment is done automatically, but while there is the facility for conductivity (EC) to be done this way also, Paul prefers to dose up manually. Generally he adjusts (tops up) the nutrient morning and evening, but in very hot and humid weather, he restricts it to evenings only.

The nutrient formula is made by Perth-based company Growth Technology, and has been specifically tailored to suit his needs. There are three different seasonal formulations – one for summer, one for winter, and one for autumn/spring.

“We’ve totally changed the nutrients we use here over the years,” Paul says. “We’ve developed our current approach by looking at the plants, adding or taking away and playing around with the formula until we got it just right. Eventually we found it was best to use the three different mixes.”

According to Carl Barry of Growth Technology, the three formulations differ mainly in their potassium to nitrogen(K/N) ratios. “The faster growing plants in summer get more nitrogen, the spring and autumn crops get an intermediate nitrogen level and the winter crops get a lower level still,” Carl explains. “The potassium on the other hand, is highest in winter and lower in summer.

“We did a lot of work on this a few years ago, mainly with Paul’s system, following the rate at which nutrients are removed from the crop and how this differs with seasons – the three formulae are the result of this. The other nutrients in the mix tend to be constant and independent of the seasons.”

In terms of conductivity levels, the system is run at an EC of 0.9mS/cm all year round. This approach has come about after much experimenting with different conductivities. “I’ve been through the whole gammit,” Paul explains.

“When I started, I started it on the recommended 1.8 (mS/cm) – in those days, that was what they all believed was right. Later advice recommended higher conductivities and we played around with varying success.”

After running the system at 0.9 for some time, Paul again returned to a higher EC of 1.1mS/cm for a period. But he now believes that lettuce grow slightly more quickly at 0.9 than 1.1. “Obviously, for much of the day it’s below this level anyway,” he observes.

As far as marketing is concerned, Paul services a regular order from Coles supermarket. Coles take the same amount (164 crates) three times a week, all year round. The remainder is sold through the Perth produce markets.

The lettuce are sold complete with their roots, in lined crates. Coles specifies 12 lettuce to a crate, but for the produce markets between 12 and 20 lettuce are packed per crate, depending on the variety – with small varieties like coral for example, 20 can be packed per crate.

Like many produce growers around the country, Paul is concerned by moves among some supermarkets to phase out the use of plastic crates ( which are reused through an exchange system) and replace them with cardboard boxes.

“Crates like these are reusable (through Crate Exchange), and non-polluting,” Paul says. “I’ve even seen some that have been in use for 20 years. But if I buy cardboard, it’s $2 or so per box, and it doesn’t get used again.

“For me alone, it would be around 500 boxes per week. That’s 25,000 cartons a year – just for me, one grower!”

As a whole industry, the figures are more like millions and millions of cartons per year. Even allowing for recycling the majority, many will be discarded and the amount of wasted cardboard will be huge. Then of course there is the question of whether waxed cardboard can be recycled.

Employing 2 full-time workers and 4 part-timers, Paul Maxwell’s operation produces an average of 11,000 lettuce each week. There are seasonal production peaks of course, but the relatively mild winters and warm to hot summers means that outdoor production in WA is a year round event.

On the other side of Perth, at Waneroo to the city’s north, Andy Stigter runs another large-scale lettuce growing enterprise, Living Foods, supplying the Perth market. His system, like Paul Maxwell’s, consists of NFT tables under hail netting, and supplies 17-18,000 lettuce per week, mainly to the Perth produce markets and direct to wholesalers.

At Living Foods the lettuce ‘production line’ starts with the growing of seedlings, in a 50/50 mix of perlite and vermiculite. Despite the size of the operation, the seeding is done manually into cell trays by a staff member.

“It takes her about three hours to do over 20,000,” Andy observes.

For the first week after germination, the seedlings are irrigated by overhead sprays, after which they are moved into a ‘nursery shed’, and placed in bottom-fed trays for a further two weeks. From here they are hardened off for a few days in a shadecloth covered area to acclimatise them to the heat. After this gradual ‘weaning’ process, the lettuce seedlings enter the main NFT growing system, where they move through in quite a specific order.

“When we first plant them out, they go into the nursery tables – which have the holes closer together – and they’ll stay there for about a week and a half to two weeks, depending on how quickly we can free the growing tables up,” Andy explains.

“From there they go into the growing tables, and what we do with each variety is to mark the tables from 1 to 10. Table No. 10 is planted with the smallest seedlings, so they’ve got longer to grow before we come along to pick them. The biggest and healthiest seedlings go into the other tables, starting with Table 1.”

The entire operation comprises 130 tables, each of 10 channels, and the whole growing area is enclosed by hailcloth. The NFT delivers a flow rate of 0.5 Litres per minute, and during heat waves, overhead sprays are activated manually, to cool the whole area down. “It mainly helps the workers, half the time,” Andy jokes.

The system runs at a conductivity of 1.2mS/cm. Here too the water source is an underground bore and, though the water emerges as a light brown ‘tea’ colour, no major problems have been encountered with its use. A two-part Growth Technology brand nutrient is used, and the nutrient tank (10,000L capacity) is topped up daily with appropriate quantities of A and B concentrate – “We know exactly how much we need to add to achieve a certain EC value,” Andy observes.

Conductivity and pH are checked once or twice each day using conventional hand-held meters.

In terms of produce range, six main varieties of lettuce are grown – Red and Green Coral, Mignonette, Buttercrunch, Green Festival and Red Festival. The enterprise markets somewhere between 17-18,000 lettuce per week. In addition, Andy also grows a small quantity of Radicchio to service a niche market in Perth.

“It’s got a limited market – we would send around 6 crates to market and some of our direct clients buy it also. It has good weight. All the growers who grow radicchio, only produce a small amount of it.”

The turnaround time for the lettuce is around 6 weeks in summer, but stretches out as the days get shorter in winter. “In mid winter, it can double to 12 weeks,” Andy notes.

Frosts are sometimes experienced during winter, but to counter plant damage, the overhead sprays are programmed to come on automatically, when the temperature falls below a certain point. Lettuce are packed in plastic lined crates – 16 lettuce to a crate. While most of the produce is sent to the wholesale markets, there are also a number of clients who deal direct with the farm. These are mainly wholesalers who phone in an order and then come to pick it up. Direct deliveries are not offered by Living Foods, mainly because of the extra staff and vehicle requirements.

Hydroponic fancy lettuce producers have carved for themselves a significant niche in the Perth market. With the often extreme summer temperatures and accompanying low rainfall, a system such as NFT which irrigates plants constantly, while recirculating the nutrient water, has offered great benefits.

The sandy soils of the Perth region mean that the water demand of soil-grown crops is very high. The comment has been made that soil growing in this area is really a form of run-to-waste ‘sand culture’ in any case! But quick turnaround times and clean and consistent produce are ensuring quite a marketing edge for the hydroponic lettuce industry in WA.


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