Early February is an ideal time to sow chillies, peppers, and aubergines, which typically take a few weeks to germinate and benefit from a long growing season to ripen their fruit. Towards the end of February or through March, the tomatoes can be sown, followed by the cucurbits: summer and winter squash, cucumbers and melons. These are all tender crops that will not germinate at low temperatures, will be harmed by frost, and will have growth retarded by cold conditions. Seedlings do not always recover fully from an early check in growth brought on by low temperatures. With low temperatures, poor light levels, and the danger of frosts until the end of April, here in the south, and even later further north, it is rather challenging to raise these seedlings at home, and with something in the order of 180 pots to deal with this becomes quite a chore. Propagators are a fairly vital piece of equipment in this process.
In previous years, we have sown all of these tender crops indoors, where the room temperature, at least during the day, is more suitable for germination. We have a large collection of Stewart propagators. These comprise two robust plastic trays – a green tray with drainage holes that fits inside a black tray without holes. One could, of course, just buy the black tray. On top is a rigid clear lid of reasonable height. They come in full and half size, and we have a dozen of the full size and a couple of small ones. Unlike many others, they are not at all flimsy and have lasted several years. I have no doubt they will be good for quite a while yet. Even when we no longer need the lids, the trays are useful throughout the season. My only complaint is somewhat poor ventilation – a couple of annoying little sliding tabs on the top that don’t always provide sufficient ventilation and are not nearly as convenient as the rotating vents that some others offer – including the Vitopod that is the main subject of this article. Nonetheless, they have served us very well indeed.
These propagators help to maintain suitable warmth and humidity for germination and offer protection to the newly germinated seedlings. However, as they are unheated, germination must be carried out indoors at this time of year. Then the challenges begin. Maintaining suitable temperatures is only half of the problem; perhaps even more challenging are the poor light levels at this time of year. Even placing the propagators at the base of some large bright windows, the seedlings still tend to become a little drawn and leggy. When the weather is favourable I have sometimes moved the propagators onto our balcony so they get some good light during the day, but in the end a time comes when the seedlings must move down to either our small glasshouse or polytunnel. The former probably offers best light, but the latter produces a somewhat diffuse light that might be beneficial. One could invest in some artificial light, but, I think that might be going a bit too far for our kitchen garden.
Whilst the light may be improved by moving to the glasshouse or polytunnel, there is then the difficulty of keeping the seedlings warm enough. It does depend, of course, very much on the weather. During cold spells the propagators are covered with several layers of fleece at night for extra protection. I have not lost any seedlings to frost using this method. On the other hand, day time temperatures cannot be helped and growth can be slow. Conversely, in sunny conditions, the microclimate within the propagators can become very hot indeed. Last year, caught out by an unseasonably warm and bright sunny day, I managed to scorch my first sowing of chillies and lost most of them. A second sowing was needed. This was not entirely the disaster that I initially thought it might be. Later sowings develop much more quickly under improved temperatures and increasing light levels and can catch up with stunted early sowings that have not been so fortunate with the conditions.
The danger of a bright sunny day is rather difficult to deal with – good ventilation, and removal entirely of the propagator lids at the right times is critical. However, something can be done to improve the early stages, from germination to keeping the tender seedlings warm, and that is to invest in a heated propagator. Of course, one could heat an entire glasshouse, and if a little attention is given to insulation, it might not be too uneconomical to heat one of modest proportions. However, I am not particularly keen on trying to heat an entire glasshouse and have in the past used a homemade construction of 10mm twin wall polycarbonate, heated with a 50W heater with thermostat. It served to keep the frost off, but was not at all convenient. I use it now for providing a little night time protection when the tomato plants have been potted on waiting to be planted in their final positions.
This year we have a real treat – two large Vitopod propagators from www.greenhousesensation.co.uk. After scouring the market, reading various reviews, and calculating the costs to house the quantity of seedlings that we produce each spring, the Vitopod came out on top. We did look at adding heating to our existing collection of unheated propagators or buying some of the heated Stewart models, but in the end, the convenience of a larger unit swayed the decision.
There are cheaper options, especially if one opts for a fixed temperature, but for a fully controllable propagator of good quality, Vitopod seemed ideal, and two of the larger model, at 111cm x 58cm, should provide enough space for all of our needs.
The Vitopod propagator provides a black plastic base containing the heating element so that it is protected from moisture and damage. This base seems to be particularly rigid and robust. Instead of a one piece lid, the Vitopod is constructed with individual side and end panels joined with what appear to be small nylon nuts and bolts. This has the advantage of allowing additional layers to be added to provide more height, whether for growing on or overwintering larger plants. We bought them with one additional layer. On top are two separate lids. Overall, this scheme seems to work well, but there is, of course, a loss in rigidity. On the large model that we bought, the long panels are made by joining two shorter pieces, which is a little unfortunate. When placing two layers, we decided to stagger these joints, as oddly these panels are not of identical length. The material appears to be a fairly robust acrylic, though, so I am hopeful that it may survive the rigours of intensive use. It is claimed to be treated to prevent UV deterioration so we are expecting the sides and lids to retain their current clear condition.
Unlike our collection of Stewart propagators, the Vitopod offers excellent ventilation with large rotating inserts placed in the centre of each end panel and in each lid. From the base of the propagator comes a lead with a standard 3 pin plug. Supplied was a modern looking thermostatic control with a display of current temperature, set temperature, indicator of whether the heater was currently on or off, with controls for adjusting the set point. The thermostat has three leads: one terminates in a moulded socket into which the propagator can be plugged; one terminates in another 3 pin plug for the supply; and the final lead terminates in a sealed metal probe that measures the temperature. This can be laid on top of, or pushed into, the growing medium to ensure that the ideal temperature is maintained where it is most important. The control is set in 1 degree increments from 5 to 30 degrees with a 100W heating element. Within the already protected environment of the polytunnel, this should be adequate to provide good temperature control even during cold nights.
Assembly was straightforward, and our first impressions are certainly favourable. The only area that we felt could be improved was the rigidity of the side panels. Overall, though, this appears to be a good quality product, and one can see how so many positive reviews have been garnered by it. The flexibility of the larger model is particularly attractive.
We have only just put our first seeds into one of the propagators, but already I realise the convenience of keeping them in one large unit, under, hopefully, ideal temperature conditions, in the polytunnel rather than indoors. When they germinate the somewhat better light conditions in the tunnel should help, along with continuing regulated temperatures that ought to prevent checks in growth. To make economical sense, these new propagators will have to last for some years. They seem robust enough; time will tell, but at the moment, I am delighted with this addition to our gardening equipment.