Is It Worth Buying A Heated Propagator?

With over 49 years of experience supplying propagators to gardeners, we have often been asked ‘Is it worth buying a heated propagator?’ Our experience tells us that it is, but below we will explain the different reasons why it is worth buying a heated propagator, together with advice on what you should consider when choosing the correct heated propagator to suit your gardening requirements.

Why Do You Need A Heated Propagator? 
A heated propagator is basically used to help germinate seeds and root cuttings.

We know that seed germination is fast and successful if the compost / soil temperature is warm and constant.  The exact degree of warmth needed will depend on the plants you are trying to grow.  The RHS suggest a temperature of approx. 19 degrees Celsius for most plants.  Some plants may need lower and some plant may need higher temperature. 

We also know that you can not achieve that type of compost temperature at all times of the year and in all locations - whether you are located in Edinburgh or Surrey, have your trays full of seeds to germinate in a greenhouse or kitchen window. 

We know that moisture levels play an important part in seed germination - too much or too little are both harmful - and being able to control the humidity is important.

Plus we know that for healthy growth - so after germination and when the seedlings appear - you need good lighting to ensure plants grow strong and sturdy.

With all the above in mind, the simplest way to be able to control all these factors and create the ideal germination environment is to use a heated propagator.

PLUS . . . and this is a big plus for many gardeners . . . using a heated propagator enables us to create this environment 'out of season' allowing us to start growing earlier . . . in fact making it possible to grow all year around.  

So, to achieve this we need to purchase a heated propagator. With so many propagators available to gardeners it's easy to buy one which is either too simple and won't achieve the results we are striving for, or is too sophisticated for our needs, meaning we overspend on features we don't need and won't use. 

Hopefully this guide which looks at what features to consider when choosing a heated propagator will ensure you get the best value for money and that your propagator will start you off to a great gardening year.  

Size Is Important with A Heated Propagator
When it comes to choosing the correct propagator to suit your requirements, size should be one of the first things to consider.

The Number Of Plants You Wish To Grow
If you want to germinate a few seeds in your home then you don't need to splash out on a 7ft 6in long electric blanket with thermostatic control, rather a compact propagator which just generates an even base heat will be perfect. On the other hand, if you have a large greenhouse or polytunnel, and want to raise plants for charity or to sell them, you might want a propagator on a grander scale.

If you have plans to grow more exotic species of plants which may have specific requirements to successfully germinate, then you might be best to select a heated propagator with precise temperature control combined with grow lights to create the perfect environment for growth.  

Your Available Space
Always match the propagator you choose to your available space, remembering that a heated propagator will need access to mains electricity. You also need to take into account the available light in the area you plan to place your propagator.  For successful, healthy growth there will need to be either sufficient natural light or access to grow lights (grow lights as part of your propagator or independent). 

Let's take a closer look at a couple of heated propagators - one, a simple, compact unit and the other a larger, more sophisticated propagator.

Window Sill Heated Propagator

This robust heated propagator has been specifically designed to fit neatly onto a window sill - which means that anyone, even if you only have a very small flat with only one window which you can use, this compact design will be perfect!

Long and narrow, it's 76cm x 18.5cm (30 x 7¼ inch) heated base will provide the heat needed to turn a cool, draughty window sill into a nursery space for new seedlings, taking advantage of the ideal light conditions and combining it with an even base heat for successful seed germination. 

To make best use of the slimline space - and providing you with maximum flexibility - this propagator is supplied complete with seven individual seed trays with vented covers. This means you can grow a large number of plant varieties on just the one unit all at the same time. 

This heated propagator is not thermostatically controlled - rather it has been designed to increase the ambient compost temperature by around 8 degrees Celsius. For the majority of seeds this will be ideal, helping to create a reliable environment for growth. For new gardeners this 'set-and-forget' type of heated propagator will be one of the simplest ways to start germinating your own plants. However, if you need to reach a specific temperature for germination then you need to select a propagator which allows you to set the required temperature. 

Being a heated propagator you need to ensure you have an electrical socket within reaching distance of its 90cm mains cable so you can plug it in. The heated base of the propagator contains a 13 watt carbon fibre element for even heat distribution. Using just 13 watts makes this economical to run.  At the current cost of electricity (March 2024) it would only cost around 9p to run if it was turned on for 24 hours a day.  

Click here for full details of this Window Sill Heated Propagator.

If you have more space for propagation and want the ability to raise more seedlings at the same time then you should look at a larger heated propagator - such as the Vitopod below. Still small enough - and stylish enough - that it can be used in your house if there is sufficient light.  If light is an issue then the Vitopod is also available with grow lights. 

Vitopod Heated Propagator

Enabling the adventurous gardener the ultimate environment for every stage of propagation the Vitopod is height adjustable with the addition of extra cover layers. With the purchase of a Vitopod you receive clear side panels and lid to cover the heated base. This is perfect for the start of the propagation process when you want maximum heat and humidity.

As your seedlings develop you can increase the height of the Vitopod by purchasing more cover layers. These are sets of side panels which securely rest on the side panel below, each time increasing the height by approx. 15cm. The robust design enables you to have up to 11 layers on the heated base whilst remaining stable. 

Excellent humidity control is enabled by using the adjustable vents in both the lid and side panels of the Vitopod's cover. You can control air flow and humidity by adjusting the settings of the air vents which is especially important during seed germination or rooting of cuttings. For example, as your seedlings develop you can open the vents to reduce humidity and increase air flow, helping them to grow strongly and harden them off. 

Perfect temperature control is easily achieved with the use of the Vitopod's digital thermostat. With a temperature range of 5 to 30 degrees Celsius, it accurately maintains the temperature you require using its temperature sensor which you can insert into the compost or place within the cover of the Vitopod. 

You can ensure your seedlings receive sufficient light for healthy growth - no matter where you position your Vitopod you can ensure your seedlings or cuttings receive sufficient light by purchasing the propagator complete with LED grow lights. Simple brackets fix to the clear lid to hold the lights at the optimum level above your plants for the correct level of light for strong, healthy growth.   

Don't forget to be practical when choosing this propagator as you will need access to mains electricity for the heated base and an extra socket if you are using it with the grow lights. Even though this is a sophisticated unit, its running costs are still economical. The standard size is 50 watts and the large Vitopod 100 watts.  Providing heat to your seeds for 24 hours should only cost approx. 70p and adding the LED lights will increase the running costs slightly.

Click here for full details of this Vitopod Heated Propagator.

Controlling The Temperature Of A Heated Propagator
When it comes to controlling the temperature of heated propagators, not all propagators are the same! There are in fact so many different types of heated propagator available to gardeners that you will find some which have no temperature control, some which maintain a 'fixed temperature' and others which allow you to set a desired temperature which the propagator's thermostat will use to turn the heat on and off automatically.

With this in mind, the simplest - and usually the most economical to purchase - are those heated propagators which you simply plug in and turn on. An example of this would be our Fixed Temperature Propagators. 

Fixed Temperature Heated Propagator

The manufacturer of these heated propagators has incorporated an inbuilt fixed temperature thermostat which is designed to maintain a compost temperature of 19 degrees Celsius. This means all you need to do is plug the unit in and it will automtically turn the heating element off and on to maintain that temperature.

So that you can see when the heating element in the base unit is turned on, there are two neon lights at one end of the propagator. One indicates 'power on' - so you have plugged the propagator in and the electric is switched on. The other indicates 'heat on' and this light will automatically turn off and on as the fixed thermostat works to maintain the compost temperature.

Don't worry when the 'heat on' light is turned off - this just indicates that the temperature is 19 degrees Celsius or above. This could be because the room temperature is 19 degrees or it could be that the heated base has been emitting heat until 19 degrees was acheived and has now turned off until the temperature falls.

If you are concerned that the fixed thermostat isn't working correctly, you can test the unit quite easily. Just place something very cold - like a frozen bag of peas - onto the base and leave in place for about 15 minutes. You should see the 'heat on' light comes on to show that the temperature has fallen and the thermostat has turned the heating element on to increase the temperature.

Click here for full details of this Fixed Temperature Heated Propagator.

You might wonder why this manufacturer selected 19 degrees Celsius as the temperature to maintain - the reason is that according to the RHS most seeds need a temperature of around 18 degrees Celsius to germinate. You should always check the seed packet which will indicate what the germination temperature required is. If you find that many of the plants you wish to grow require a higher germination temperature, it's time to look at using a propagator with the variable thermostat where you can set the temperature. 

What Is A Thermostat?
In simple terms a thermostat used with a propagator is used to monitor and control the temperature within the growing environment.
It is an electrical unit which your propagator is usually plugged into and is then is plugged into a mains socket. It will have a controllable temperature range which will allow you to set a desired temperature – via buttons or dial. It will monitor the temperature via a temperature sensor which you can usually place in the most temperature critical area.
When the temperature you have set is reached it will turn the heat source off and on to maintain that temperature. In that way it will help you to maintain the optimum growing temperature and at the same time ensure power is not wasted.

The Heat & Grow Variable Temperature Propagator is a nice step up from a fixed temperature propagator as it has a low purchase price for a heated propagator where you can control the temperature - you will tend to find that with a thermostat which lets you set the temperature the purchase price will increase as you are paying for this more sophisticated temperature control.   With this thermostat you simply turn the dial to the required temperature - this thermostat has a temperature range of 12 to 28 degrees Celsius.

The thermostat above is wired directly into the Heat & Grow Variable Temperature Propagator. The next step up from this is to have a propagator which is plugged into a thermostat - as long term, this enables you to replace just the thermostat or just the propagator if anything goes wrong outside of the guarantee period. The thermostat with the Quadruple Propagator is this type.

Air Vents Are Vital For A Heated Propagator 

By having air vents in the top section of a heated propagator it helps you to manage the temperature and the humidity within the propagator – both of which are vital when using a propagator to germinate seeds or root cuttings.

The adjustable air vent shown in the photograph opposite is easily turned by hand to allow air into the propagator. This style of adjustable air vent is featured in the best-selling Vitopod propagator and you will see lots of different styles of air vents depending on which heated propagator you choose. As long as the air vent is easy to use and robust enough to be adjusted on a daily basis then the shape or style is not significant.

When using a heated propagator to germinate seeds, then the clear cover of the propagator helps to retain heat and humidity which the seeds need to germinate. Once they have germinated, they don’t need as much humidity and actually need fresh air in order to grow. The shock of removing the whole cover / lid of the propagator would be too great when the seeds have just germinated, so this is when vents enable you to gently reduce humidity and introduce fresh air without shocking the seedlings.

When using a heated propagator with cuttings it is always recommended that the cuttings are kept hydrated but not too wet – in fact if your cuttings become waterlogged and devoid of air then they will rot rather than form roots. So being able to provide ventilation in the propagation area is important – with cuttings it is recommended that for the first week the vents are kept closed and then opened and closed just once a day to let in some fresh air. Then the vents can be left permanently open until the cuttings root – this can take between 2 to 3 weeks.

Do You Need Seperate Compartments In A Heated Propagator? 
With so many manufacturers of heated propagators and so many different sizes and styles, you will find some which have separate compartments and others which have a single cover fitting over the heated base. There are pros and cons in both cases, so let’s take a look at the propagators which do have separate compartments first and how these can be a benefit.

Fab4 Heated Propagator

This compact heated propagator is ideal if you are new to propagating your own plants from seeds as its four seperate compartments let you raise different types of plants all at the same - controlling the temperature and humidity by adjusting the air vents. 

The Fab4 is also great if you only have limited space - it's 40cm x 23cm (15½ x 9½ inch) heated base takes up very little room and you may even find that it will sit neatly on a windowsill.

Coming from the heated base of this propagator is a mains cable approx. 130cm in length - so you just need to make sure you have an electrical socket within the distance so you can plug it in.

Designed to give an even base heat across the full area of the base it has a carbon fibre element built into the watertight base. It has a low wattage of just 8 watts - this means that at the current cost of electricity (March 2024) it would only cost 6p to run if it was turned on for 24 hours constant use.

With this Fab4 propagator there is no thermostat control - for new gardeners this can be useful as it means it is just a case of turning the propagator on or off as required. But this also means you can not set a temperature - it simply increases the compost temperature by around 8 degrees Centigrade compared to the temperature of the room the propagator is being used in.

Click here for full details of this Fab4 Heated Propagator.

As we can see from the example above, having a propagator with seperate compartments lets us grow more plants which might have different germination times or germination temperatures at the same time in the same propagator - assuming we can control the temperature using the adjustable vents in the compartent covers, as is the case with the Fab4 heated propagator. 

The limitation with this is the size of the compartments. It restricts the number of seeds you can germinate or the number of cuttings you can root. What you will find with propagators with just a single cover is that you could create your own 'compartments' in which to germinate different seeds by using your own seed trays or plant pots within the main cover of the propagator, placing individual covers on the trays or pots.   

A good example of a heated propagator with a single cover where this is encouraged is the Heat and Grow Variable Temperature Propagator.  This electric propagator is supplied complete with two small and one large seed tray, together with 10 small flower pots.  These can be used within the heated base of the propagator to provide you with lots of choices when sowing seeds or cuttings.

As the size of the heated propagator increases then the more likely you will find that it comes with a single top cover. It is then up to you whether you use seed trays, pots, modular trays, rootrainers etc. within the propagator, using the single cover to retain the heat and humidity. Take a look at the Bio Green Jumbo Propagator below: 

Bio Green Jumbo Heated Propagator

Described by the manufacturer's Bio Green as the 'ultimate propagation station' this heated propagator has been developed to make it easy for you to start propagating on a large scale. 

The heated part of this propagator is a 1.2m x 50cm (3ft 11in x 19¾in) heat mat. This mat provides an even heat distribution, with an electric heated wire encased in splash proof, foil insulation. You can place your plants in pots, seed trays etc. directly onto this mat. Providing heat from below stimulates rapid and vigorous growth in seedlings and cuttings.

Coming from the heat mat is a mains cable approx. 120cm in length - so you will need to have an electrical socket within this distance so you can plug it in. The power comsumption of this large heat mat is an economical 150 watts - at the current cost of electricity (March 2024) it would cost £1.04 to run if it was turned on for 24 hours constant use.

Larger propagators tend to have more sophisticated temperature control than smaller heated propagators. The Bio Green Jumbo is a good example as it includes a digital thermostat that allows you to set any temperature from 0 to 40 degrees centigrade. This precise temperature control allows you to germinate more demanding plant species. Once the set temperature is reached the thermostat will turn the heat mat on and off to maintain this temperature - helping to ensure your seedlings aren't over heated and that you don't waste energy maintaining too high a temperature. 

For a more humid atmosphere use a piece of capillary matting or water matting on top of the heat mat - you could also keep your heat mat in perfect condition by protecting it from compost and soil marks by covering is with a piece of black polythene or perforated polythene before placing your pots and trays on top. 

To create a spacious, protected, propagation space this heat mat is fitted within a sturdy tubular framework covered with a high cloche cover. This ventilated, clear cover retains heat whilst minimizing condensation and allows you easy access to your plants via zipped end and side panels.

With a protected growing space of approx. 50cm in height means you can use this propagation station as a place to over winter more delicate plants. This means that if you only have a small number of plants to over winter, a heated propagator with a single, high cover means you don't need to heat your whole greenhouse, which should help keep heating costs to a minimum.  

Click here for full details of this Bio Green Jumbo Heated Propagator.

Watering Options With A Heated Propagator
When you are using a heated propagator you will be dealing with plants when they are at their most vulnerable - when they are new seedlings - and over or under watering can be the difference between them growing or rotting away. With this in mind, there are a few basic pieces of equipment you will need to ensure you get watering correct. 

Depending on which variety of seeds you are sowing, you will probably need to ensure the compost in your seed trays or pots is moist.

To help create a humid atmosphere within your propagator, which is helpful for successful germination and growth - you will need to introduce more water into your propagator. To do this safely - and to ensure seedlings never get stood in a pool of water - we would recommend using a piece of water matting or capillary matting between the heated base of the propagator and your seed trays or pots.   

Water matting is the modern replacement for sand and gravel, but has the advantage of being lightweight, easy to install and simple to keep clean to prevent the spread of disease.   It is a bonded / non woven material - so a bit like felt - which is simple to cut with a pair of scissors. When you put water on the matting it acts like a sponge, soaking up lots of water and preventing trays or pots from being sat in a pool of water.

To make watering plants in a propagator as easy as possible - foolproof if possible, so you neither over nor under water your plants - ideally you would have a propagator with built-in self watering. Unfortunately you won't find many self-watering propagators available to domestic gardeners, but we have found a few which will do this for you.

The simplest one is the Hollandia heated propagator from Bio Green: 

Bio Green Hollandia Self Watering Heated Propagator

This slimline heated propagator is ideal for new gardeners as it combines all the useful features of a 'set-and-forget' propagator with the unusual but useful feature of built-in self watering.

With a 1.4 litre / 2½ pint reservoir all you have to do is keep this topped up with water. Capillary matting carries water from this reservoir to the base of the seed trays as it is required. This means it's simple for you to ensure water is available to your plants - but it also prevents you from over-watering them which could cause disease or make them rot. 

The reservoir is also the heated base of the propagator - with the heating element safely built-in to the watertight tray. This also ensures a humid atmosphere is created, which seeds need to germinate successfully.

Another plus with the Hollandia is that it is really energy efficient - using just 12.5 watts of power means that at the current cost of electricity (March 2024) it would only cost 9p to run if it was turned on for 24 hours constant use.

It features a 'set-and-forget' fixed temperature thermostat which means all you need to do is plug it in and turn it on. It is then designed to increase the compost temperature by around 8 degrees Centigrade compared to the temperature of the room the propagator is being used in.

Being an electric propagator don't forget you will need an electrical socket so you can plug it in - this is made easier as the mains cable coming from the heated base is approx. 1.8m in length. 

Click here for full details of this Hollandia Heated Propagator.

If you are a more advanced gardener or are wanting to grow a wider range of plants with more demanding germination temperatures, then the other self-watering propagator may be more suitable - and is one which we designed ourselves at Two Wests & Elliott - the Varitemp Heated Propagator.

Two Wests & Elliott Varitemp Heated Propagator

We designed this heated propagator for those gardeners who wanted accurate temperature control, but only had limited space. So we combined one of our long-lasting, aluminium heated trays with a precise digital thermostat and added in a set of sturdy half seed trays and vented covers.

What we also did was produce a self-watering model - ideal if you struggle to keep plants correctly watered or simply to reduce the amount of time it takes to water. Simply top up the 12 litre / 21 pint reservoir with water and you can forget about watering for up to two weeks!  

Transferring the water to the seed trays is capillary matting, which only supplies water as it's required. Keeping your seed trays out of the water is an aluminium support tray - so your plants roots are never sat in water. The heated tray rests on top of the water reservoir - which means it helps to create a humid atmosphere which is needed during the propagation process.

Providing an even base heat across the full surface of the aluminium tray (so there are no hot or cold spots) it has been designed so that no heat is wasted - with heat directed towards the top of the tray rather then been wasted through the base of the tray. Plus, it's an efficient 70 watt unit - so at current costs of electricity (March 2024) it should only cost 49p to be turned on for 24 hours constant use.

Controlling the temperature is easy and precise using the digital thermostat included. With a temperature range of 10 to 30 degrees Celsius and a temperature sensor which can be used to measure either compost or air temperature, you can create the exact germination environment for your seeds. 

Click here for full details of this Varitemp Heated Propagator.

Is It Beneficial To Have Lights Included With A Heated Propagator?

Light plays a really important role - if not a vital role - when propagating plants from seeds and cuttings. If light levels are low then this will result in plants taking longer to root. However, when lights levels are high this can stress plants, causing unhealthy growth, leaf droppage etc. So, getting the right amount of light during the propagation process should result in steady, predictable germination and growth, with healthy root structures and sturdy, strong plants.

So, when positioning your propagator ideally it needs to be placed where there will be good natural daylight. But realistically, this isn't always possible and this is one of the reasons that you find propagators now available that incorporate lights. 

This Deluxe EarlyGrow Propagator is a perfect example of a heated propagator that incorporates grow lights as standard. The lights included are Cosmorrow LED grow lights which provide a blue spectrum of light ideal for propagation. Unique to this propagator is a thermostat that enables you to control both heat and lights - so you can set the lights to turn off and on automatically.

If you have a heated propagator which doesn't have the choice of a model with grow lights, then it's now possible to buy just an LED lighting Kit which is quick and easy to fix to any propagator which has a rigid cover with a smooth surface above it, as shown below:

Propagator LED Lighting Kit

With this lighting kit you will receive a pair of LED Grow Lights and the fittings needed to mount these onto the top cover of your propagator. All you need to do before purchasing the kit is make sure your propagator has a solid lid - so rigid plastic - which has a smooth surface. Also, measure the length of the propagator to make sure you purchase the correct size of lights.

The Eco LED Grow Lights supplied are high efficiency, high output, low wattage lights which produce a full spectrum light to replicate natural sunlight for year round growing. They are perfect when propagating from seeds or cuttings and are equally good when growing salads and herbs all year round. These lights can also be used to boost flowering house plants out of season! 

The lights are supplied in pairs and should be fixed in parallel with each other and should be no further than 23cm / 9in apart. When positioning the lights on your propagator lid they should be centralised to the length of the cover and supported equally at each end of the light with a support bracket.

The support brackets supplied include suckers which make them easy to attach securely to a smooth surface. Clear, acrylic brackets then fit to the sucker and slide over the grow light to hold them saftely in place. 

Click here for full details of this LED Lighting Kit.

Be Practical When Choosing A Heated Propagator
As yet – and if you know different, please let us know – we haven’t been able to find a heated propagator that is powered by anything other than electric. So, when we have customers wanting to have a propagator at their allotment – where they have no mains electric - or even in their greenhouse – not everyone has mains electric to their greenhouse – we have to be practical and suggest their heated propagator is placed in a spare room etc. where mains electric is available.

This also means that when you are choosing an electric propagator you need to know the length of the mains cable – as you will need a socket within reaching distance to plug it in to. Plus, if you have a propagator with grow lights this could mean you need to have two sockets – one for the propagator and one for the lights.

Plus, check the size of the propagator you propose to purchase against the size of space you have available – this is really important, especially when purchasing online. Take into account if the propagator has a lid which you will need to lift on and off – you need space to do this with ease.

When Using A Heated Propagator Always Remember
Any heated propagator will only give a lift of approximately 11 to 14 degrees Celsius above the ambient / room temperature. For example, if it is 4 degrees Celsius in the area you have your propagator – the ambient temperature – then the maximum temperature in the propagator will be approximately 18 degrees Celsius. This means in the colder months of the year a propagator must be in an area with a minimum ambient temperature of 7 degrees Celsius to achieve the 19 degrees Celsius that many seeds need to germinate. 

The Cost Of Using A Heated Propagator
As you have seen above, different heated propagators have different wattages - although they are all considerably lower than an electric heater!  

To help you with calculating the running costs we have created a simple table below which shows you the power of the heated propagator and the cost to run per hour and per day, if running constantly, with an electricity cost of 29p per kWh (the current UK Price Cap January 2024 - excluding the UK daily standing charge of 55p per day). 

Just remember, the costs above are the maximum if your propagator was on continuously for 24 hours. In reality, if your propagator incorporates a thermostat, then it will automatically turn off and on to maintain a set temperature, so should not be constantly running unless you are trying to maintain a high temperature or the ambient temperature is much colder. You also need to take into account if you use grow lights with your heated propagator as these would have a running cost which would need to be taken into account as well.

Our guide to a heated propagator has been created from our personal knowledge, information gathered by speaking to other gardeners or manufacturers in the gardening industry, by reading gardening magazines and devouring information from books and the internet. We aim to be as accurate as we can, so if you find a mistake, please remember, we’re only human. if you have any queries you can contact us today!