Greenhouses | Page 4 of 14

Aubergines, a blog by our resident horticulturalist Peter Whyte

March is about as late as you can sow aubergine seeds and expect a reasonable crop. You could sow as early as late January if the weather is mild enough or if you have frost protection heating in your greenhouse. Cell-trays allow you to plant the young plants with less root disturbance, so they grow away faster than plants pricked off from traditional seed-trays. Sow two seeds per cell (if both come up snip out the weaker one). Place them in a heated propagator or on a warm windowsill; the ideal temperature is 20-25°C (68-77°F). Keep the compost moist but not wet. The seedlings can take up to three weeks to emerge.

Set out the plants in your greenhouse as soon as their roots fill the cells or the first flowers appear, if by then you can keep them above 10°C (50°F) or so at night. Night-time fleece covers help. Alternatively pot them on into slightly bigger pots that can be brought into the house at night. Space the plants about 45cm/18 inches apart for normal, and 30cm/18 inches apart for dwarf varieties. Pinch out the growing point s of the main stems when about 25cm/10 inches tall to encourage the plant to bush out. Keep conditions warm, bright and humid.

Pollinate early flowers with a small paintbrush; later flowers should need less help. Start liquid feeding with tomato food when the first fruits form, and mist the plants with water to discourage red spider mite. Leave no more than five fruits per plant and remove further flowers to divert their energy into filling the existing fruit. Remove dead bits from the plants to discourage grey mould fungus, and watch out for slugs, whitefly and greenfly. Good varieties to try are ‘Black Prince’, ‘Dusky’, ‘Bonica’ and ‘Giotto’.

Phones operational again Thank God

Delighted to say our new phone system has been installed. We just need to get used to the new buttons and bells and whistles and tweek things a bit. Customers should also hear professionally recorded on hold messaging. Thank you for having borne with us.

Current Phone Situation

Our new phone system is due to be installed on Tuesday which will be a terrific relief.

In the meantime please bear with us. We have only one incoming phone line working and have had to divert that to a mobile.

You can of course email us at info@polydome.ie

We will be open for visitors as usual on weekdays and on Saturday from 9am to 5.30pm (closed for lunch between one and two).

You can get directions to us on the How to find us section of the home page of our website.

Many thanks, Jonathan Pyle

Director

Phone system issues

In case anyone is having any difficulty getting through to us, I apologise. Our Eircom phone system has gone kaput and they say that replacement parts are not available now that it is 7 years old (after charging 180 euro for one hour to advise me of that). I like the idea that whenever something goes wrong to use the opportunity to improve the situation even better than it was before the event – so we will be installing a new more efficient system as soon as the new providers who are based in Birr as it happens can do so. Have to pat the new people (Intellicom) on the back, I called and enquired about a new phone system, within one hour a sales man was in our office, two hours later he was back with a technician to do a survey and before the end of the day a quotation received and price agreed. Way to go lads.

In the meantime while we are sorting out this issue please contact us on (086) 805 8550 or email us at info@polydome.ie

New Janssens Greenhouse Brochure

Janssens have launched their new 2017 brochure, it is nearly three times the size of the previous one at 64 pages. Just click on the image of the brochure to view it on drop box.

We can send anyone who would like to view it a link to do so online. Hard copies have not been received yet but will be available free of charge to all visitors to our display area. Glad to say we were involved in helping in a small way with this brochure by editing text and supplying images.

Lime scale

If last year you had problems with lime scale blocking up your greenhouse watering system, now is a good time to sort them. Hard water may eventually block up greenhouse sprinklers and seep hoses. Even if you have a water-softener for the house, it may not be economic to soften the water used in the garden. Buying new sprinklers and seep-hoses every other year is expensive and wasteful when they can easily be cleared.

Disconnect blocked seep-hoses and coil them neatly into the bottom of a large plastic bucket. The white plastic buckets with lids that garden products are often sold in are ideal. Put any plastic sprinkler components into the middle; it’s best not to add any metal parts as they might corrode. Following the manufacturer’s instructions, add de-scaler (lime scale remover) to just enough water to cover the hose in the bucket. Always wear hand and eye protection when doing this, and never handle powder products in windy conditions or you may get an eyeful. Snap on the lid tightly and put it out of reach of children and pets. Somewhere warmer is ideal as the chemical reaction between the de-scaler and the lime scale runs faster. When you need to re-install the watering system for the new season, pour the water away carefully where it won’t cause pollution and rinse all the parts with clean water.

Growing early Lettuce

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.

End of the line – by our blogging Horticulturalist Peter Whyte

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.

How to handle Grey Mould in Greenhouses

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.

Pelargonium Cuttings

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.