We have had a few questions in comments and on twitter recently about our set up in the greenhouse and how we use the propagators so I thought it would an excellent opportunity to talk to you a bit more about the process from start to finish.

The first thing I want to point out is that Kate and I don’t have a heated greenhouse, or use heated propagators. The process of sowing, growing and hardening off however, is pretty simple and is the same for all of us, heated or not.

Sowing and growing

We have learned over the past few years that we need to be very aware of the temperatures around us and the weather in our part of the country. We love watching gardening shows on tv and reading about other gardeners and what’s happening with them, but it’s equally important to remember that what works for Monty Don may not be what works for me here in Scotland. We have different weather and temperatures at different times. So I keep a journal where I can record the dates when I sow, what the temperature was etc so that over the years I can learn about what works best for me.

Hence why we don’t start sowing, even in the greenhouse until March when twitter and instagram make it look like everyone else is sowing in February.

I did used to sow my seeds in the house and keep them on a sunny window sill to start off. This worked a bit like a heated propagator I suppose and got things going quickly, but I found that the seedlings were usually leggy as they tried desperately to reach for the light coming in the window, so have taken to just waiting a couple of weeks and sowing in the greenhouse when it’s warmer. This way I have stronger seedlings.

Very leggy seedlings

Over coming the cold

We don’t have a heated greenhouse and we don’t use heated propagators. To be honest, I could imagine that having this option would probably speed things up, but I don’t find it is absolutely necessary either.

We put all our sowing in standard, non heated propagators. Make sure the vents are open and leave them in the greenhouse where they get light and a bit of protection from the cold, but the greenhouse is just warm enough to let things get started. We keep things in the propagators until the seedlings have at least their second leaves.

There have been some plants where I know from my records, there are issues getting them to germinate, for instance I have had problems with jalapenos, in this case, I have a mix of propagator sizes so I put the seedlings into a smaller unit and then pop that into the bigger propagator. Double bag it if you will, to help build more heat.

Just one of the things I have found works.

I have seedlings how do I safely move them out of propagators?

So you have your lovely seedlings and you think thy are ready for a move to the big girl playground… This is a biggie in the comments and on twitter just now. Whether you are using heat or not, before moving plants out of your propagator, you do need to “harden them off”. This just means acclimatising them to life outside of your propagator. You want them to get used to things gradually and for them to develop so they can survive either in the greenhouse or outside. You do this gradually to prevent your plants from going into shock.

So I do this once my seedlings have at least their second leaves, but also I am aware of what the temperatures are. Last year for instance we got a sudden blast of icy weather. You want the greenhouse to be at a reliable, steady temperature during the day before you start.

Step 1 – So, I start by opening the propagators during the day and then putting the lids back on for the night. I do this for a week or so. It means the plants get used to the slightly lower temperature of the greenhouse during they day where they don’t have the extra build up of warmth from the propagator but they are still protected from the cold over night.

the more delicate seedlings getting their first draft of non propagator are.

Step 2 – After a week or so, when I feel the plants are looking healthy and can cope, I then leave the lid off the propagators completely, all day and all night. I keep an eye on the seedlings though and watch for any sign they are not happy. Again I usually do this for at least a week.

If you used a heated propagator, I would say maybe add a step to this. Begin by switching the heat off in the propagator and let the plants get used to have no additional heat. Then after a week of this, move to the next step, take the lid off during the day.

Again there is no hard and fast rule for everyone, you just need to keep an eye on your plants and go a bit by your gut.

Leaving the greenhouse

Once your plants are happy in the greenhouse without the protection of the propagator, it’s time to consider when would be suitable to let them experience the outdoors. Ideally you want to be sure there will not be another frosty spell, so I usually wait until the night time temperatures are a stable 5 or 6 degrees C. This way I can be pretty much sure there wouldn’t be a sudden frosty night. BUT I keep an eye on the weather and if it looks like we might get a frost, I bring them back into the greenhouse.

Step 3- So, I do this much as I do in the greenhouse. I start off by putting the plants out side, in their pots, during the day and bring them back into the greenhouse at night.

It’s scary to leave them outside for the first time.

It’s good to remember that there will be more than just heat for the plant to content with now. Think about sunlight, shade, garden pests, so do keep an eye on things.

Step 4 – After a week or so, if the plants are looking happy I move to leaving them out over night, still in their pots. Again, keep an eye and watch how the plants settles. There is no rush, it is more important that you have healthy strong plants than you rush things and end up with no plants. That would be sad.

We are all aiming for happy, healthy plants.

Hopefully that will help allay any worries about your lovely new seedlings 🙂

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Eli

We are Kate and Eli and we love gardening, growing veggies and cooking.

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  • Hi
    I just read your information and I don’t have a greenhouse but I bought a heated propagator and this is the second year I have tried to grow some herbs and they are spindly, it’s a small house with not much light and the windowsills are very narrow, we live in Northumberland so our temperature is way different to anyone else.
    Would I be better getting a grow light garden, I don’t know what else can I do?

  • Yeah – unfortunately spindly or leggy plants is usually a sign that they are desperately trying to find the light (reaching out to it) and it’s really common for things grown on the window sill. You might find some cheap grow lights might help. You don’t have to spend a fortune, I got some for my houseplants for about 20 quid. Sometimes even a white grow bulb in a normal desk lamp is a great option.

  • Hi Folks
    Love your site. Some really good informative videos, along with some good sound advice based on your experiences. No frills and fanciful ideas, just good old down to earth straight talking.
    Quick question; I noticed in one if your videos where you are checking the propogator soil temperature you were using a digital thermometer. Was wondering what make it was as I wouldn’t mind getting one.

    Jimmy

  • ha ha ha here we go back to the no-frills thing Jimmy…. it’s the candy thermometer form the kitchen drawer.
    I also use analogue long probe thermometers too… if you pop up to the top of the youtube channel or this blog, you’ll see a link to a page where we have all the kinds of gear we use. Might hep you get some ideas for when you are searching

  • Cheers Eli

    Much appreciated and good luck with your gardening and greenhouse efforts. Based here near the north east coast of N. Ireland we probably encounter similar weather and gardening issues as you do in Scotland

    Take care

    Jimmy

    Jimmy

  • Hi. I’m new to using a propagator. I have one which uses plugs but also has a tray – I presume for larger pots. I’ve tried to grow seeds and only had about 6 out of 50 germinate.
    How much water should be in the base – I.e. should it be up to touching the plug.? I don’t have a greenhouse so have to out it on the sunny window sill of the utility room. Many thanks. Ann

About Us

Eli

We are Kate and Eli and we love gardening, growing veggies and cooking.

About Us

Eli

We are Kate and Eli and we love gardening, growing veggies and cooking.