It’s easier at this time of year to buy imported lettuce than grow it in your greenhouse or to grow rocket, endives and oriental greens instead, but lettuce is preferred in many households and home-grown is much fresher. Choose varieties that are tolerant of short days and low temperatures, and resistant to mildew. ‘Little Gem’ and ‘Winter Gem’ are cos-type varieties, ‘May Queen’ and ‘All the Year Round’ are butterhead types, and ‘Salad Bowl’ is a looseleaf type for cut-and-come-again harvesting. If in doubt check the information on the back of the seed packet.
You can sow the seeds thinly and 1cm deep in the greenhouse soil. Keep the drills about 30cm apart and thin the plants to the same spacing when they are big enough. This wide spacing leaves plenty of air between plants to discourage mould and slugs. Sow a little every two to three weeks for a succession of crops.
It’s easier to sow the earliest batches in cell trays with small cells. Sow just a few seeds in each. Keep them indoors to avoid slugs and mould, and don’t let them get warmer than 25°C (77°F) or they won’t germinate. Thin the plants to one per cell with a fine-pointed scissors as soon as they are big enough to work with, and plant them out as soon as their roots have bound the compost in each cell together. Keep the plants well watered, and ventilate the greenhouse whenever the weather allows. Water in the morning to allow the plants and soil surface dry out before night. Protect the plants from slugs and remove all weeds, dead leaves and rubbish. Harvest hearted lettuce by pulling whole plants, and looseleaf types with a scissors, leaving the plants to grow more leaves.
Clearing out your greenhouse for the winter gives you a chance to clean it and let in more light, but also to look after the soil. If you grow tomatoes and other crops in grow-bags or containers, don’t put the peat from them in the bin. It is a scarce and dwindling resource that should be used to the full; use it to improve the soil elsewhere in your garden, or mix it with soil for planting trees and shrubs. Alternatively, give it to a neighbour who can use it.
The organic matter in greenhouse soil decomposes quickly in the warm conditions. You need to replace it or the soil becomes hard and cloddy, and plants grow poorly. Sowing green manure, digging it in and waiting for it to rot down in the soil delays the next crop; the quicker option is adding well-rotted garden compost or other organic matter. Level the soil and spread the compost on top. You could leave it there and let nature take its course, but read up on no-dig gardening first. If digging it in, turn it under with a spade. Work slowly to avoid damaging the sides or cladding of the greenhouse. A small greenhouse is one of the few places where a short-handled back-breaker spade might be better than a proper long-handled one. Leave it to settle for a few weeks before sowing or planting in another crop.
October is the month when production of greenhouse tomatoes, aubergines and peppers usually comes to an end. With falling temperatures and longer nights, growth is slowing down and your plants will be less able to ripen fruit. Remove all flowers as they are unlikely to set usable fruit in time for them to ripen this late. Thin out some of the fruits already set, especially the smaller ones. Stop shoots from growing any more by cutting off their tips. The above actions divert all the plants’ resources into filling the remaining fruit, so you get bigger, riper, tastier fruit instead of many small unripe ones. Do this earlier or later depending on your location and how mild the autumn is.
With the rising humidity, disease control becomes more important by the day. So make sure to remove any dead leaves, spent plants, weeds, rubbish and dropped fruits from the greenhouse. Open the vents or doors on sunny mornings, but close them up earlier in the evening before it gets too cold. Feeding should have ended in September, and watering should be reduced to match the plants’ lower needs. As a rule of thumb, don’t water until the soil surface is dry. Avoid wetting the leaves.
By about mid-October it can be too cold to ripen tomatoes well. If so pick all the fruit and ripen them indoors in a dark, airy cupboard. Don’t leave them on a sunny windowsill: if they once get heated above 35°C (95°F) the red pigment is destroyed and they stay pale and blotchy. Some people put a ripe apple or banana with them to speed up ripening with the ethylene gas it gives off. Remove plants when their fruits are all picked, and clean up the greenhouse for the winter.
Great first day at the National Ploughing Championships, very busy and not a drop of rain. Traffic management seemed to go very well. If you haven’t been come and see us on Row 8 Block 3 Stand 195. A lot of interest in Livestock Tunnels for calves and for sheep as well as Polytunnels for gardening.
Horticulturalist Peter Whyte gives Polydome customers some tips on how to deal with Grey Mould.
Grey mould is a common disease of greenhouse plants in late summer and autumn. The key to controlling it is knowing how it lives and ensuring that it doesn’t get a grip. It is a fungus disease, caused by several different Botrytis species. The commonest one in greenhouses is Botrytis cinerea, which attacks unhealthy, dead or dying plant tissues. If that was all it did, it would be little trouble to growers and just another useful organism recycling our plant wastes into compost. But when established on dead or wounded plant parts it then attacks the neighbouring healthy tissues, killing them back too. It produces a forest of tiny hair-like stems on the surface of the plant, each one ending in a capsule of microscopic dust-like spores. This is the visible ash-grey mould. When you disturb the plant, the capsules release clouds of spores to attack more plants. Some land on tomato fruits where they fail to penetrate unbroken skin and die out, leaving ‘ghost spots’ with white edges and almost transparent centres. Affected tomatoes are edible but don’t look attractive.
Control the fungus by denying it food. Dead-head plants often and remove dying or infected leaves, stems and fruits right away. Never leave fallen fruits on the ground. Water regularly to reduce leaf die-back and fruit splitting. Reduce humidity by ventilating well, thinning out dense foliage, spacing plants further apart, removing weeds and watering only in the morning so plants and the ground surface will be dry all night. Feed plants less nitrogen (which encourages soft, sappy, disease-prone growth) and more potash (which encourages slower, harder, disease-resistant growth). Prune and de-leaf plants in the mornings so the wounds dry off before night. Disinfect the greenhouse and dig over the soil in winter to reduce resting spores.
Pelargoniums (geraniums) are easy to grow from cuttings whenever the plants are growing, but easiest in late summer. Fill a pot with seed compost and moisten it by standing it in water for a while. Then let the surplus water drain away. Choose your healthiest, most vigorous pelargonium plants for cuttings. Non-flowering stems are best because flowers give off hormones that inhibit root growth, but if you have to use flowering stems remove any flowers and flower-buds. Stout stems grown in good light are better than spindly stems grown in poor light; a few weeks on greenhouse staging can produce good stems.
Cut the chosen stems below the third node (joint) from the top. Cut off all but the top leaves, insert them into the pot leaving one node and the top leaves showing and firm them in gently to ensure good contact between the cutting and the compost. Place the pot in a warm bright spot out of direct sun. Don’t cover it as dampness can rot the cuttings. For the same reason, water it only from below by standing the pot in water for a while and letting it drain as before. Remove any cuttings that start to rot. Plant out the rooted cuttings when new leaves appear on them: let them recover where they were until growth starts again before placing them in full sun.
Looking forward to seeing new and existing customers at this years Bloom Show which starts this Thursday and runs until bank holiday Monday. Our stand is in the same place as the last two years, OR39.
Bloom is regarded as a great day out for all the family, and it looks as though we will be blessed with fine weather (God willing).
This year we will have a lovely Janssens Helios Orangery Greenhouse on show which can also be used as a Garden Room and will be an attractive feature in any Garden. It is a big Greenhouse at 3.92m x 4,76m, it is 2m high at the sides. The kit starts off in price at 6,770 euro.
Congratulations to our Happy Couple Marilyn O’Connor and Paulus Ungerechts who bought a Polytunnel from us this Spring and when the venue for their wedding reception ceased trading unexpectedly they improvised and used their Polydome Tunnel as the venue!
Here is a link to the story in the Irish Independent yesterday. Irish Independent Story
Very appropriate too as Polydome was founded on Saint Valentines Day 1985!
Cherry tomatoes on the vine
For a successful crop of greenhouse tomatoes you need to get the planting right. The plants should be a healthy green colour and not yellow (due to lack of feed and/or water) nor purplish (due to chilling), nor lanky and spindly (due to lack of light). Plant them out when the first flowers are opening. From then on plants will need more food and more room for their roots to forage for it.
The greenhouse soil is the easiest and cheapest to plant into but you can’t keep planting tomatoes (or any other crop) in the same soil every year as pest, disease and mineral problems will build up. Change the soil for fresh soil from outside the greenhouse, or move the plants around a large greenhouse each year, or use grow-bags.
Traditional vine tomatoes grow straight up to head height or more and can be spaced only 45cm /18” apart. Bush tomatoes need less headroom but much more space between them. Keep any seed packets or labels for guidance.
You need canes or twines to support vine tomatoes. Canes are easier to use but must be inserted before putting in the plants to avoid damaging their roots. Strings are simpler at first, but as you twine them around the growing plants they may need to be slackened at the top so use a shoelace knot and leave extra twine on the end.
Water the plants well before putting them in, and again after planting. Make sure the soil around the root ball is wet so the roots can grow into it: greenhouse borders can become very dry. Leave the plants slightly below the surrounding soil so water poured onto the bases of the plants won’t roll away from them.
When seeds have been sown and germinated in a seed tray, the process of separating the tiny plants and transplanting them into individual pots or containers is pricking out. It’s an essential skill for greenhouse users who raise plants from seed. Do it as soon as the seed-leaves on the new plants are opened out fully: delaying longer allows their roots to intertwine so that separating the plants damages them more severely. Fill compost loosely into the containers to be planted up. Level it but don’t firm it down. Using an old teaspoon, a metal tag or similar, dig under a seedling from the side as you lift it by one of its seed-leaves. Lower the roots down into a hole punched in the centre of the potting mixture in the target container and tap the container to level the compost around it. Firm it gently with your fingertips and water it. Set it somewhere warm, sheltered and out of direct sun until the plant recovers from the shock of transplanting and starts growing again.
Avoid sowing seed too thickly in seed-trays, as the seedlings end up too close together for easy pricking out Do as little damage to roots as you can while pricking out so the plants will recover and grow faster. Always hold seedlings by one seed-leaf and never by their stems: stems are much easier to crush than leaves and a plant with one damaged leaf still has another.
If a seed-tray is too congested because of sowing thickly or delayed pricking out, all is not lost. You can still cut the solid block of root-bound compost into squares, pot up each square and reduce the plants in each to one by snipping out the rest.