Grow Your Own Plug Plants

, written by Jeremy Dore gb flag

Plug plants

Plug plants are seedlings which have been germinated and grown in trays of small cells.  When the roots have grown sufficiently they can be easily pushed out of the trays and either transplanted into larger pots or planted outside in the ground.  Plug plants used to be largely confined to bedding plants and flowers but all that is now changing as edible gardening becomes more popular. Many nurseries and seed companies have started to sell a range of vegetable plug plants and these offer a very easy route to starting a productive garden.   So what are the benefits of using plug plants and are they worth producing yourself?

The principle advantage of plug plants is that the roots can be kept relatively undisturbed when transplanting them into their final growing position.  Even the most experienced of gardeners will end up losing some soil from around the roots when seedlings are eased out of seed trays. Growing them as plug plants helps minimize this because the shape of each cell encourages the roots to bind the soil into a single plug which doesn’t fall apart when removed. The densely packed trays also mean they are a very economical way to raise plants, particularly if windowsill or greenhouse space is limited.

Plug plant tray

This year I have decided to experiment with growing my own plug plants, starting them off on an indoor windowsill.  Although I could buy them from a garden supplier I chose not to because:

  • Growing my own plug plants gives me access to a much wider range of varieties than are commercially available.  My first tray, for example, consisted of 14 different varieties of lettuce and salad leaves.
  • Home grown plug plants are cheaper and can be raised in several batches to allow for variables which can’t be controlled such as a cold spell of weather.
  • Few plug plant suppliers offer organically grown plants.  I suspect that the huge greenhouses they are raised in require plenty of pesticide management techniques that I prefer to avoid.

That said, the option to supplement a garden with commercial plug plants is certainly one I can understand.  Raising young seedlings inside is time consuming as they need carefully looking after at each stage – moisture levels must be just right, plenty of light but away from draughts and cold etc.  Get it wrong and they end up with stunted growth which they may never fully recover from!  So, buying young plants from a local nursery or mail-order catalog is an attractive alternative if you want to guarantee success or replace any early-season disasters.

For starting off the seeds I used a great product produced by Agralan from a clever Swedish design called the ‘Compact Plug Plant Trainer’ (available in North America from Veseys).  Each tray fits neatly onto a window ledge and consists of 49 cells.  The bottom of the tray acts as a water reservoir with an ingenious capillary system to draw up just the right amount of water.  The lid can be orientated to allow ventilation or keep in warmth and when turned upside down it creates small dents in the soil for locating seeds.  Finally, when the plug plants are ready (shown by a few roots making it down through the bottom of the cells) two side catches are released and the bottom tray pushes the plug plants up and out.

[In many ways this is the baby sibling of the increasingly popular Root-trainers which are similarly shaped pots, encouraging the good deep root growth which is particularly useful for pea and bean crops.  The main difference is that Root-trainer pots divide into two halves to access the plant, whereas the Agralan Plug Plant tray pushes them out from below.]

Plug plant

As the plants begun to reach the necessary size I started the usual process of taking them outside for increasing periods of time during the day to harden them off.  Then, simply pushing the plants out with the bottom tray I was able to transfer them into my newly prepared salad bed (complete with slug trap of course!)  An added advantage that I had not anticipated was that this made it much easier for my 7 year old son to help me.  I am normally rather protective about the seedling stage, when so much careful attention has gone into raising these precious little plants.  The plug plants were so simple that my son quickly got the hang of making a hole in the bed with a dibber, lifting the plug plant up by the leaf (to avoid squashing the stem), dropping it into the hole and gently firming the soil around it.

Overall, the process has been no more difficult than my usual indoor seed sowing but with some clear advantages.  Less disturbance to roots, a self-watering system which worked well and the opportunity for my young children to be more involved with this early stage of gardening.  I will be keeping a close eye on the plants to see how they compare to my usual crops but my expectation is that the lack of root disturbance will produce excellent results. Raising your own plug plants may not have the convenience factor of buying them from the nursery but the satisfaction of growing many varieties from seeds makes up for that.  I think I am well and truly hooked on plug plants!

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Show Comments


"I've just ordered a plug starter on the basis of this article--will let you know how it turns out. I had used a Burpee self-watering greenhouse kit, and while it was great in terms of keeping the seedlings moist, I fear I ruined more than a few when trying to get them out for potting up."
Shannon on Friday 3 April 2009
"Hello! This is my second year sprouting veggie plants in grow trays and I'm expecting the same great results as last year. I find that using the bottom tray layer to push up all the plants at once just too much to handle. Instead I first gently press the soil down around the seedling just in case the root ball didn't fill the whole cell, then just manually push up each seedling from it's little cell with my longest finger (even with my small hands). Compressing the soil a bit allows me to gently grasp the plug with the other hand. I can then drop it right into a pre-dug hole in my grow bed. The plug system I use is the APS (Automated Propagation System) from (a North American site). It comes with a capilary mat to ensure evenly-moist soil and a plastic dome to capture the heat from your grow lamp. I find it to be as close to "setting and forgetting" the seeds as possible (although I can't resist to check their progress daily!) "
Sarah on Friday 3 April 2009
"Sarah, Yes, I like to check my seeds progress daily, although I have just been away for 4 days and the trays have self-watered wonderfully. Thanks also for metioning the APS system."
Jeremy Dore on Friday 3 April 2009
"I've just planted outt the last of my 150 or so salad leaf plants from one large plug tray. Plenty for our three families, some for my allotment neighbours and lots and lots in pots (3 or 4 varieties to a pot) for a plant swap Transition Tynedale is holding in a few weeks time. The idea is to have a range of salads in a pot for people who are new to veg growing or who have little garden. The next set of seeds will go in later this week. Plug plants are wonderful and So easy to manage and I agree with Jeremy that it is worth growing your own, even just becuaes you can choose your own varieties. For the past two years I have been getting quite a lot of seeds from the Real Seed Company that have some wonderful lettuces. Bronze Arrowhead is a particular favourite, lovely flavour and very resistent to bolting."
Peter Samsom on Monday 13 April 2009
"I grow with plug plants buying seeds from garden centres and sowing one to a cell, so that I know where the seedlings will be. It's much easier to pot up, as Jeremy said!!"
Lil laura on Thursday 16 April 2009
"hi i just looked up sarahs APS website by cutting and pasting the link. I got a page on wedding garters opps. think it must be ps i am really excited about looking into these syatems as my 3 year old really wants to help in the garden and I don't have much space for growing seedlings. looks like it will be the perfect sollution. thanks"
anna on Monday 20 April 2009
"Have a question, I know its best not to let planst get root bound as this can stunt thier growth. How does this relate to plug plants who's "roots to bind the soil into a single plug which doesn’t fall apart when removed". Is it to do with the timing of planting out or potting on?"
anna on Saturday 25 April 2009
"Anna, It's a good question. As you suggest, the trick is to get the timing of when you pop the plug plants out just right. You want the roots to have grown sufficiently so that they bind to the earth in the plug but not so much that they are going round and round, like a pot-bound plant. The photograph above shows the ideal time to plant out. I think getting this right is one of the trickiest things when first growing plug plants because until you pop them out of the tray you don't know what stage the plants are at. After a few goes you get used to what size the plant must be for the roots to be ready - about 2 inches high in my experience though it depends what you are growing."
Jeremy Dore on Saturday 25 April 2009
"Update--the seedlings in my ‘Compact Plug Plant Trainer’ are doing great. It's not time to plant them out yet, but in terms of germination rate and overall health I'm having much better results with this system than with either the Burpee ultimate seed growing system or the APS system. True test will be transplanting, though."
Shannon on Saturday 25 April 2009
"I've been making my own newspaper pots for the past 3 years and find them even better than plugs; there is no chance of disturbing the roots as the whole pot is planted directly into the ground and the roots can easily grow through the damp newspaper. Making the pots themselves can also be quite therapeutic. "
Quentin Duerden on Thursday 14 May 2009
"Hi, thank you for your information on this page. My wife and I have a small organic farm in Lake Stevens WA, where we are currently growing vegetables for market. We are, however, very interested in growing plugs commercially, because we now have 5500 sq ft of greenhouse space and this fall will add another 2800 sq ft. Can you tell us what direction, publication or helpful website to go to?"
David Mills on Wednesday 7 April 2010
"Hi David, I would recommend contacting your state university's extension office who will often have very good advice for starting out in commercial growing. For example, Alabama have this helpful document: Good luck with your venture!"
Jeremy Dore on Wednesday 7 April 2010
"I also just ordered the compact plant trainer because as Shannon stated, I too have been using the Burpee self watering starter kit and I know I am doing a lot of damage to the root system with this set up. I'm looking forward to starting my own plugs with damage free roots!"
Kimmy on Tuesday 4 May 2010
"I used the Agralan planter for American Land Cress. Forty-nine seeds yielded forty-nine plants. On a cut and come again system they have withstood the recent extreme weather."
Ernest Weston on Saturday 15 January 2011
"Hello: A little off topic here. What about those peat pots, (those brown mossy looking pots )to start seeds it much of an advantage to start seeds in those. Someone gave me a bunch, don't know if I should use them or not. Thanks Gaia"
Gaia on Monday 11 April 2011
"Peat pots can work well for seedlings that don't like having their roots disturbed when being planted out - squash family plants and eggplants etc. Personally I woudn't use peat unless I was given them like you but there are some similar biodegradable pots available made of things like coir. They're quite expensive though and careful handling of squash plants in regular pots has alwasys worked OK for me."
Jeremy Dore on Monday 11 April 2011
"I call the plant babies and they are so fun to grow. I start over 4000 every year in packs of 72. A little late this year due to a busy schedule, but hoping to start peas, potatoes, radishes and carrots in the ground soon too. I sell at markets or trade with friends. Grow Good Things."
Bridget on Wednesday 15 April 2015
"What kind of soil would you use with plug plants, for cuttings? Would coir be ok?"
Gar Howell on Saturday 6 May 2017

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