Don’t let snow accumulate on your Polytunnels and Glasshouses

The Polydome Display Area with most snow removed from roofs in advance of the promised blizzard.

As the whole country is bracing itself for the ‘Beast from the East’ we would like to advise customers with Polytunnels and Glasshouses that once it is safe to venture outside you should remove snow as it is surprisingly heavy and can collapse structures if allowed to build up excessively.

If you have an electric heater for use in Greenhouses (specially sealed for a wet environment) you could leave it running as the warmth may help to melt snow before it has a chance to build up.  If you have a direct fired heater – e.g. a gas heater that works like a gas hob inside a metal cover, only leave it running if you can be positive that there is a fresh air supply to it that will not get blocked (otherwise it will burn up all the oxygen and produce carbon monoxide with potential disastrous consequences).

Any number of ways (such as soft bristled brushes, sheets, mop handles etc.) can be used to dislodge snow but whatever you choose try not to damage your polythene or glass in the process, so use something soft so that it will not scratch (causing reduced light transmission) or tear the cover or break the glass.

It is also possible to prop the roof inside your Greenhouse or Polytunnel, but of course this should be done before snow builds on your structure in case it could collapse while you are in there.

We hope that everyone will be safe and well which is the most important thing, your Greenhouse or Polytunnel can always be replaced – and you may even have insurance to cover it, but of course it is not worth taking any risks to protect it.

Carrots for May

You can buy carrots in the shops almost any time, but nothing beats your own early carrots for flavour and juicy crunchiness, harvested just before eating in spring. Carrots sown in a tunnel or glasshouse in February are ready to eat about late May, well before any crop sown outdoors would be ready.  In milder areas, seed can be sown in January for even earlier crops.

The traditional varieties such as ‘Amsterdam Forcing’ or ‘Early Nantes’ are as good as any for early sowing. Border soil for sowing carrots should be light, stone-free, without recently added manure or compost and above 5°C.  Sow the seed thinly in drills about a centimetre deep and 20 cm apart.  If the soil is very poor you could sow them in large pots of prepared compost or compost/soil mixture.  Cover the drills or pots with fleece on cold nights to keep the soil as warm as possible: the warmer the soil the faster they germinate and grow.  Protect the emerging seedlings from slugs, and as soon as they are big enough to handle thin them out to about five centimetres apart.  Do not let the soil dry out, as it stalls growth and the carrots can split when watered again.  If not eating harvested carrots right away, cut off the leaves to prevent them drying out and shrivelling the roots.

Wash pots

Things can be quiet in tunnels and glasshouses right now; cold weather, perhaps even still turkey torpor (lethargy) to turn your attention elsewhere. But you know that soon you will want to begin sowing new crops.  When you do, wouldn’t it be nice to just grab seed trays and pots and use them without having to clean them first?  It’s good to get them all washed together now so you can choose the exact pot you need and use it right away, and as they are all clean none can carry forward pests or diseases to the new crops.

Gather all empty pots, saucers, seed trays, tools and equipment. Bin any cracked or broken ones.  Place a big bucket on a stool or in a wheelbarrow to raise it up so that you don’t need to stoop.  Fill it with water (a kettle of boiling water can take the chill off) and add some (preferably eco-friendly) detergent.  Some like to add a bit of disinfectant but if you had no major pest or disease problems last year a good washing should be enough.  Scrub them well with an old washing-up brush, rinse them in a bucket or jet of clean water and leave them to air-dry.  To save even more time later, sort them by shape and size when stacking them away.


Christmas 2017

We at Polydome would like to wish all our customers, friends and suppliers a lovely Christmas and offer our best wishes for the coming New Year.

We will be closing on Saturday at 1pm and reopening on Tuesday 2nd of January at 9am.

The Polydome Team


If radishes were harder to grow, we might plant them more! Maybe because their fast and reliable growth makes them an ideal crop for children to plant, adults tend not to bother with them so much.  But if you are sowing green salad crops in autumn and early winter, why not enjoy some crunchy fresh radishes with them?

Sow the seed very thinly in drills about one centimetre deep and fifteen centimetres apart. The soil should be tilled finely with no clods.  Keep the soil moist and as warm as you can in winter, watering them when needed with water that has been stored a few days in the greenhouse to avoid chilling the plants.  Cover them with bubble-wrap on frosty nights, but remember to take it off again in the mornings.

Warm moist conditions and radishes are attractive to slugs, so take precautions against them: one slug can wipe out a whole row of seedlings in one night.

Some radish varieties are better than others for winter sowing under cover. Check the seed packet before you sow, but try some anyway – radishes are very accommodating and the seed is not expensive.

Pesto and radish bruschettas

Soil warming cables

Christmas is coming and people are getting stressed by questions such as ‘what present can we get for (fill in the name yourself)?’ If they have a tunnel or glasshouse, how about something to increase their enjoyment of it?  They could use a soil warming cable in so many different ways that it is almost certain to expand the range of plants they can grow and/or extend their growing season.

The theory is simple. The cable is buried below the surface of a bed of ‘sharp sand’.  When warmed by electricity it warms the surrounding sand, in turn heating the soil or peat moss in pots and seedtrays sitting on the sand. Soil temperature affects plant growth more than air temperature.  Seeds germinate faster, cuttings root sooner and growth continues when the air temperature drops a bit too low for normal growth.  Insulating fleece or bubble-wrap over the plants will protect them from a few more degrees of frost due to the rising heat.  Adding a thermostat will save electricity when the sun warms the soil naturally; see soil warming cables on the Polydome website. You can heat a whole bed or just a small propagation area, but if the latter it’s more convenient to have it on a raised bench or staging in which case you should place insulation underneath it.

Electricity and water are an unsafe mixture. Make sure you use a qualified electrician to lay on power to a glasshouse or tunnel, and follow the installation instructions carefully.

Successful 2018 Ploughing Championships

Good to be back from exhibiting at the National Ploughing Championships 2018 show which had a record attendance.  Great interest in our Polytunnels, with enquiries spread from small domestic Polytunnels, Sheep Tunnels, Polytunnels for calves and cattle, Multispan Greenhouse structures covering an acre and even bespoke (custom made) Glasshouse enquiries.

Being located at Tullamore last year and this year it is very convenient for us to attend and the access has been better than any other location that the show has been at (in our experience).

Now to get back to all these potential customers to take their orders (and then break out the pressure washer to clean off the mud)

Janssens Greenhouses price increase imminent

Janssens had advised some months ago that due to pressure on materials costs their Greenhouse prices might need to be adjusted at the end of August.  We have been advised that there will be an increase of 5% at the end of this month.  If anyone is thinking of ordering at this time of year it would be a very good idea to order before the end of August as after that date a new price list will be operational.


Florence Fennel – by horticulturalist Peter Whyte

You could sow many crops now to produce vegetables for the autumn and winter. One worth trying that you might not think of is Florence fennel.  Its aniseed-flavoured bulbs can be braised or eaten raw and the young stems and leaves can be chopped for soups and salads.  The seeds can also be used either fresh or dried for flavouring.

The key to growing Florence fennel is to keep it growing fast and steadily without any checks from drought, cold or transplanting. Its natural habitat is Mediterranean marshes, so it is not used to checks to growth.  Sow the seed in modules or peat pots and snip out the surplus seedlings to leave one in each.  Protect the young plants from slugs.  Keep them well watered with water warmed by letting it stand in the greenhouse for at least half a day.  Plant them as soon as possible into warm, moist but well-drained, fertile soil with plenty of organic matter.  Space them about 35 centimetres apart.  Keep the plants well-watered, weeded and ventilated, and feed them little and often.  You can earth up the developing bulbs to blanch them if you prefer.  If you don’t need the space for following crops, don’t dig up the plants when harvesting.  Cut through the base 3 centimetres above ground level and leave the stump to produce tasty sprouts for salads later.


Tomato Blight – gardening tips from horticulturalist Peter Whyte

Tomatoes and potatoes are so closely related (compare their flowers) that they are both susceptible to Late Blight. Of all the fungus diseases that attack tomatoes, blight is the most severe.  In warm, damp weather in July the tiny fungus spores drift in through open doors and vents, and germinate quickly where they land on damp plants.  The fungus spreads out to make large dark spots on the plants that join together and blacken whole leaves or stems.  Brown sunken patches appear on the fruits and they rot.  Mould then appears on the surface, releasing more spores to spread infection.  There are no approved sprays for blight control on tomatoes, so use cultural controls instead. 

The spores are spread by wind, hands and water-splash. Close doors and vents on cool days to keep the spores out.  On warm days open glasshouse vents and tunnel doors to air out the greenhouse.  Keep leaves dry by watering onto the roots; avoid overhead watering.  Water in the mornings so the plants are dry by nightfall.  Remove the lower leaves by breaking them upwards (not cutting, as the wound heals slower) and break out side-shoots to improve air circulation around and through the plants.  Remove all potato crops from the greenhouse by mid-June to stop them infecting the tomatoes.  Remove and destroy infected leaves and fruits immediately, before they infect their neighbours, but wash your hands before handling healthy plants.  Don’t compost infected material as some spores can survive composting.  Grow tomato varieties selected for blight resistance such as ‘Ferline’ and ‘Legend’: they are not fully immune but it helps.