Seedling production at Nga Rakau Nurseries

August 2016

A specialist contract seedling producer of a wide variety of crops

Nga Rakau Nurseries was begun by the Beaumont family in the 1930s at Mudgeways Road, Massey, Auckland which is still the home base. It began as an open ground nursery growing pip and stone fruit, shelter, hedging and some trees.

Today Nga Rakau is a specialist plug or cell tray nursery with a diverse product range covering vegetables, flowering annuals, perennials, cut flower lines, herbs, native and re-veg species, particularly manuka, and some forestry lines.

Owner Mark Struthers is the third generation here, the grandson of the original owners.

There are two sites, with a nursery and office at Mudgeways Road, which is 10km from the new Hunter Road site.

The nursery employs 18 staff and up to 25 contractors across the two sites.

The Hunter Road site, developed two years ago, is used to grow vegetable seedlings (mainly lettuces) and manuka in plugs and cell trays. It is a state-of-the-art development, with rolling benches and a lot of automation.

All of the other crops are grown at the 20ha Mudgeways Road site which contains a 60x70m greenhouse with a production shed attached, and outside is an 80x60m area of rolling benches. There’s another area of 50x90m for growing manuka.

All the plants they grow are contracted before sowing. “If people want 500 or 10,000 plants they specify a date they want them, and we grow them,” says Mark. “We were growing out of our other site, which is more difficult because it is sloping so looked for a flat site where we could automate things. We slowly built the infrastructure with bores, roading and track work.”

“We designed the frames so they can be stacked and de-stacked automatically off a big cassette. Trays are automatically de-stacked and dropped onto a conveyor where they are filled with mix, swept, brushed and sent through the seeding machine.

The seeder has the sowing schedule for the week, with labels all printed for each customer and bar codes for each seed lot. If the seeder and the bar code information for the customer don’t match, the screen flashes red.

Each tray is sown and counted off seven at a time, before being swept onto a frame. The frames run down to the end of the house, in line with rails and air rams lift the trays off the frames. About three people run this system compared to seven at the previous site.

The greenhouses all have automatic vents, with temperature control. Shade screens come across the plants if the sun is too bright, and fans circulate the air.

Irrigation booms are controlled by a worker with a small scanner which is blue-toothed to the boom. “It makes watering easier and very even, and the booms can speed up and slow down.”

“Young guys take to it really well. We are quite a different nursery compared to how most NZ nurseries operate.”

Mark has travelled overseas to find appropriate gear and saw the frame stacking system in a forestry nursery in Tasmania. He imported irrigation booms from Italy and the seeding machine from the US. Most of the other gear has been reinvented from material they used on the other site, or designed and built by themselves.

The rolling bench system is used in the United States but the US and European systems are too big for New Zealand so had to be re-engineered and downsized for use here.

The next project Mark is working on is to develop another boom to clip onto the irrigation booms to use for remote-controlled spraying.

Nga Rakau grows about 40 million vegetable seedlings a year.

The biggest volume of plants are grown for Babyleaf and are sold at 5cm high. Some are sold on to hydroponic growers, but most are planted in the field. As well as lettuce, they grow tomatoes, fennel, capsicums, chillies, cucumbers, eggplants, Chinese cabbage, silverbeet and herbs. “We just supply the greater Auckland area down to just north of Hamilton.”

Their seed comes in from the Netherlands, and is bred for disease resistance, growth, vigour and uniformity. Most of it is pelleted to increase its uniformity.

It takes four weeks from seeding to shipping the plants out, except in winter when it takes six to seven weeks for most vegetables.

Some of their growers give them schedules six months in advance with specified delivery dates every week. “Supermarkets want a constant flow of product every day of the week,” says Mark. “It’s a challenge to keep consistency week in week out. Just doing all the little things right is the key to the work. That’s where our new site has made things easier because we are able to be a lot more consistent with our production and systems.”

It used to take four days a week to complete the vegetable production with the gear at the home site, but on this site it takes only 1.5 days a week.

When the plants are about half-grown they are rolled out of the greenhouse to be finished outdoors on rolling benches for 10 days to two weeks.

With the huge demand for manuka for honey production, Nga Rakau has geared up to produce more than a million plants a year.

The manuka they grow goes all around the North Island. They direct seed the very fine manuka seed into cells which hold 100ml of mix, or into a tiny 5ml cell, later transplanting the smaller plants out.

Compared with lettuce seed which has a 98 to 99% germination, manuka seed and other native plant seeds have a lower germination rate.

“If a customer gives us enough time we will run a germination trail and do a percentage count, which sets us up to seed the cells with the right number of seeds.”

Using the tiny 5ml cells means customers later get a 100% full tray of bigger plug plants.

After the plants establish they are trimmed with a cutter which fits onto the irrigation booms.