Growing Like a Pro

The learning curve is always the steepest when thrown in the deep end, but there also remains the real risk of drowning. So we have taken the plunge ourselves and jumped into the depths of commercially grown vegetable seedlings to uncover the tips and tricks to starting your seedlings at home. Don’t worry, we’ve got our floaties on.

Starting your plants from seed is what all home growers should aspire to. Seeds are the most economical starting point for any garden, but they also open up a more diverse range of varieties than if starting from seedling bought from a nursery. Taking the tomato as a case in point; there are literally thousands of varieties you can sourced by seed online, yet maybe 10 when browsing the seedlings at the best local nursery. It’s commercially unviable to grow anymore and spoil us for choice - like your kid when trying to select from 32 ice-cream flavours as the queue builds - so nurseries will only grow what sells. And the less varieties they grow, the less risk there is of some not selling. That’s how supply and demand works we’re told.

Growing from seed, whether it’s more economical or opens up a greater choice of varieties or is something entirely different, is just deeply satisfying. Like when growing anything, it’s just the fact that you did it that makes it more special, so why not maximise the satisfaction by starting the process from the beginning.


The Pros

Gardening success often comes down to routine and infrastructure. And because - no offence - we can’t trust your routine, we’re going to focus a little more on the infrastructure. So we took a tour of the University of Swinburne’s commercial greenhouses and looked at their set up and processes that helped get their plants to market. 


Hot house

The first thing you notice with any commercial set up is that it typically takes place in a greenhouse bigger than most homes. So we need to find a substitute. Here are your options, in order of descending cost/effort;

  • Walk-in Greenhouse: yep, why not go straight to the top if you have the space. There’s many sizes for a walk in greenhouse and many budgets as well, so you may surprise yourself. And when it’s not being used to propagate next seasons crops, it can be used to grow chillies and tomatoes through winter.
  • Shelf Greenhouse: if space and $ is an issue, a shelving unit, covered in a plastic hood is the next best thing and more than enough size for seasonal propagation.
  • Mini Greenhouse: shoe boxed size growing space, which is totally sufficient for small to medium sized garden spaces.
  • Micro Greenhouses: plastic strawberry or cherry tomato containers, that are almost custom made for propagating a few seedlings before they hit the recycling bin. 



Plants feel as overheated and flustered as that person in the car (or maybe it’s you) who wants “just a little bit of air”, while the other seems to thrive on a steady, slow-roasting. While it may not immediately appear so, the flow of air is critical in diminishing the impact of pest &/or disease, which always find a way of getting to your babies.

Kate from Swinburne comments that “airflow is important for any plant growing in a greenhouse. By growing in a protected environment, we take away the wind, so we need to create airflow for temperature regulation and to reduce pathogen infection. Pathogens love humidity and warm environments, which is often what we are growing our plants in. In commercial setups, we create airflow in our houses with fans or ventilation, in the form of a window in the top of the greenhouse wall.”

  • Walk-in Greenhouse: Will usually have a window at the top to aid circulation and keep air moving.
  • Shelf Greenhouse: Open the plastic during the daytime when it is warm and close it back up later in the day to help trap heat overnight.
  • Mini Greenhouse: You know the little superfluous looking plastic sliders on top of your greenhouse. They seem too simple to do much, but thank them later for the airflow for your plants. Just remember to close them at night to help trap heat. 
  • Micro Greenhouses: It’s really just a matter of opening the lid, but strawberry or cherry tomato containers usually have some pre-made air holes so we don’t end up with mouldy fruit in the first place. 



It’s always water, or lack of it, that is going to derail your growing plans. So you need a safeguard to ensure that the seeds - and then once germinated, your fragile seedlings - get all the water they need. 

Growing in an incubated space is the first part in reducing evaporation and maximising every drop. The pros have all their plants irrigated, generally with overhead fan spray systems or flood trays. Is it advised to connect to a system that relies on a timer (rather than yourself), but work with what you have. Remember that the basic idea is to keep the soil/plants consistently moist, but not soaked, through their upbringings. It’s kind of like feeding an infant vs teenager; an infant needs many small feeds of milk daily, while your teenager will do with a whole pot of bolognese. 

  • Walk-in Greenhouse: Connect the greenhouse to an irrigated fan spray. You’ve gone to a lot of effort already, so best not to stoop on the irrigation.
  • Shelf Greenhouse: Invest in a spray bottle or use the mist setting on a hose. 
  • Mini Greenhouse: Use a spray bottle a few times daily to keep soil moist.
  • Micro Greenhouses: Again, invest in a spray bottle to keep the soil moist. To keep your space dry, the kitchen sink is a great halfway house for containers so you don’t spray water everywhere.

Once you make sure your plants have access to water, you then need to ensure they won’t be drowning in it! In the commercial set up all plants are elevated and are grown in containers with adequate drainage holes. Make sure you don’t commit the ultimate gardener 101 error by drowning your babies. 

Pooling water or water that doesn’t drain away poses a biosecurity threat in a production nursery, as water can be a breeding ground for pathogens as well as causing water-logging issues in plants.


Growing Substrate 

Growing substrates are varied and for the pros are dictated by the plants they are wanting to grow. It’s sometimes as delicate as someone’s coffee order, with a mix used for one plant considered “undrinkable” to another. Generally though, a standard seed raising mix is used for all seeds, while a cutting mix is used for those that are best grown from that method. They both then graduate to a general potting mix before entering the garden proper. 

 Seed raising mix

The aim of the seed raising mix is to retain moisture; with a composition of smaller particles that allow the seeds to germinate and sow root easily. Moisture is most critical to seed germination, and generally, no fertiliser is added here, that tends to come later. Main components include: 

  • Fine grades of pine bark
  • Sand for aeration and drainage

 Cutting Mix

The aim for this substrate is to hold the cuttings in place as they form roots. As the cuttings don’t have root systems to uptake water, they are instead having to access it in through the stomata on their leaves.
Used for stem cuttings, leaf cuttings its main components are: 

  • Vermiculite to hold cuttings in place
  • Peat to provide moisture retention

General Potting Mix

This is used for all our plants once they are potted on (i.e. into tubes, pots etc). Slow release (pelletised) fertiliser is added to this one, and will vary depending on the plants being grown. Components of the general mix:

  • Pine bark; coarser grade than with seed raising mix.
  • Sand for aeration and drainage
  • Coir peat (coconut fibre)
  • Gravel for stability 
  • Fertilisers for control release of nitrogen and micro nutrients

For the home gardener seek out a premium potting mix, which will contain all the requisite elements that your plants now require. 



Raise your hands if when it comes to pests in the garden you buy a product hoping for a miracle cure-all and use it like a bandaid over an open wound? Don’t worry we’ve been there too. 

When it comes to pests the pros use yellow sticky traps as a monitoring tool. They can see what is in the houses and when there is a population increase. There might also be some tell tale signs….for example, when a snail slugs its way across your greenhouse wall, leaving an unmistakable trail. Identifying the pests will then help determine what control measures need to be taken and you can go about implementing them.

Don’t freak out at the first sign of a bug, remember that not all bugs are bad. Monitor the situation and use our A-Z pest guide to help identify and choose the appropriate course of action when the scales are tipping in the pests favour. 

Starting from seed seems daunting at first, but once you take the plunge you’ll be swimming in a sea of possibilities in no time. We do believe everyone has the capacity to grow food anywhere and we’re here to hold your hand until your thumb turns green in the process. 

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