Greenhouses

Radishes

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.

Bloom 2017

BloomLooking forward to the Bloom show which starts next week – on the 1st of June through to the bank holiday Monday (the 5th).   We will have two stands this year, one for Polydome and one for Greenhouse Ireland – adjacent to each other – stand numbers OR39 and OR40.  By then our new website, Greenhouse Ireland, will be launched for showcasing Janssens and Griffin Glasshouses.  We will be showing some new gable ends on the Polydome stand – our new Aluminium Sliding Door for our Garden Polytunnels and a new steel gable with a net vent that you can open and close like a window.  On our Greenhouse Ireland stand we will have an exciting new model called the Modern from Janssens – in a mad red colour!  We always enjoy exhibiting at Bloom, so looking forward to seeing many of our existing customers as well as meeting new faces.

 

Feeding Plants – a blog by horticulturalist Peter Whyte

Caucasian man offers a watermelon

By early summer the plants that were thriving may grow slower and look a bit pale. A common cause is hunger: the roots of a plant may have filled the available compost or soil and exhausted its mineral reserves.  Plants in pots, containers and grow-bags are most at risk because their roots have nowhere else to go: at least plants growing in greenhouse beds or borders can spread their roots out a bit further.  Hungry plants grow slowly with pale leaves; their lower leaves may drop off and flowers may be small and poorly coloured.  Overfed plants are soft, lanky and leafy and the leaves may have brown spots and wilted edges.

Never feed dry plants. Water them first or the salts in the feed may scorch their leaves and roots.  Granular and other solid fertilisers are fine for crops in greenhouse soil but liquid feed is better for plants in containers and grow-bags.  Feed them only when they are growing. Never make up liquid feed stronger than advised in the instructions; the manufacturers already recommend the maximum safe level because they want to sell you more feed.  This is even more important if foliar feeding by watering it onto the leaves.  If you want vigorous leafy growth as in salads use a feed higher in nitrogen (N) than potash (K) but if you want flowers and fruit use a high-potash one such as tomato feed.  You can make your own liquid feed from soaked comfrey or nettle leaves, but one of the best organic feeds is made from Irish seaweed.

Late Frosts – advice from our blogging horticulturalist Peter Whyte

May is a dangerous month for greenhouse users. With all the talk about global warming and the evidence of it everywhere, you can easily forget that the risk of frost continues into May.  The last likely frost might be in early May near the coast, but inland you are not in the clear until end of the month.  Global warming is a long-term trend but there are still short-term highs and lows on the temperature graph.

Plants grow fast in May and quickly need more space. It’s tempting to move some plants out of tunnels or glasshouses to make room for the rest, but harden them off properly first and keep a sharp eye on the weather forecast.  Be prepared to carry them back in on evenings when frost is predicted.  And if you were tempted by the early displays of tender bedding plants in a garden centre, remember to bring them in too.  Cold frames can protect plants from several degrees of frost, and plastic cloche tunnels give some protection from lighter frosts.  Single small plants can be covered with upturned buckets or light materials such as straw or bracken fronds.  Just make sure the wind doesn’t uncover them overnight and that you uncover them yourself next morning.

 

hoar-frost on leaves

frost on leaves

Schizanthus

Schizanthus_wisetonensis_'Angel_Wings'_(Solanaceae)_flowerPoor Man’s Orchid or Butterfly Flower is a half-hardy annual which, when well grown, is covered in flowers that look a bit like orchids or butterflies. It is much easier to grow than true orchids.  The flowers can be a single colour such as white, lavender, pink and red, or be bi-coloured, and/or have yellow throats.  They last well when cut.  Like all half-hardy annuals they can be grown from seed in a greenhouse and planted outdoors after the last frosts are over.  But they can also be kept in a well-ventilated greenhouse to flower all summer.  They do very well in pots and containers, where the root restriction seems to encourage them to flower better.

Sow the seed in trays or small pots; varieties differ in their need for light for germination so follow the seed-packet instructions as to whether to cover them with compost or not. Keep them at about 60°F / 15°C for 2-4 weeks; they are slow to germinate.  Prick out the seedlings when big enough to handle, and pinch out the growing tips as they get taller to keep them bushy.   Keep them in full light but shade them from hot sun.  They prefer fairly cool conditions and become drawn and spindly if too warm.  They don’t tolerate wet so give them perfect drainage, water them only when the compost is dry on top and never leave containers standing in saucers of water.  Give them some tomato feed every two weeks.  If you have a heated greenhouse you can sow Schizanthus in August or September for overwintering.  Watch out for greenfly; the ferny foliage hides them well.

Thanks to Cambridge University for the photo.

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