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April- Winds of Change

April can be quite a roller-coaster of weather events. Night-time frosts and heavy hail showers intertwined with beautifully warm sunny days keep the daily greetings interesting. However, these ever-changing conditions can be a challenge to manage in a greenhouse setting at a time when so many seedlings are just getting established. So, this month we will discuss ways to counter some of these extreme swings.

Ventilation to let in fresh air is essential in any greenhouse. Plants require a steady supply of CO2 as they turn it into oxygen, so they can’t exist long-term in a closed off environment. Ventilation can also be used to adjust the temperature and humidity.

Temperature requirements vary between plants, but as a rule of thumb night-time temperatures between 12 and 19C and day-time temperatures between 21 and 26C are considered optimal for growth. Once temperatures go beyond 29C plants can suffer distress. A simple thermometer can be useful in monitoring this.

Ways to increase night-time temperature include closing vents overnight (preferably before sunset) to retain the daytime heat. Covering sensitive plants with frost-protection fleece or bubble-wrap can further help retain heat and protect from overnight frost.

Ways to lower temperature during particularly warm or sunny days include opening all doors and vents, the use of fans or shade netting and watering the path or other solid areas. These processes can be automated by temperature-sensors or timers.

Too much humidity sets conditions for moulds and diseases, which can be lowered by simply allowing a better flow of air via ventilation.

Inadequate humidity is usually only an issue in Ireland during a heat wave but can still lead to plant distress. Adding moisture by watering is the obvious antidote. Since day-time watering can lead to sun-scorch, watering is best done either in the morning or in the evening. But in intense heat, watering the ground or solid surfaces during the day can be useful to both slightly lower the temperature and increase humidity.

Glasshouses receive fresh air through doors, roof vents or side vents which can be easily automated. Ceiling fans can also be fitted.

Fortunately, plants are resilient enough to withstand natural fluctuations in conditions. So, with a little bit of extra care, they can really thrive in the enhanced environment provided by your greenhouse. And so can you!

March- Propagation time!

It’s March and high time to start some seeds! Here are a few tips for success.

2) Next, follow the instructions on the packet. Not all seeds are sown in the same way.

3) There are several factors involved in triggering a seed to germinate. These include light, temperature and moisture. At this time of year, the temperature is too low for certain seeds, so using a heating mat or heating cables in sand can speed up germination, resulting in a stronger plant.

4) It is a good idea to label everything clearly as you go along. This can avoid confusion later on when the little darlings start to emerge and you don’t know who is who! It is also a good idea to record when and what you sow in a notebook or diary for future reference.

5) A seed is a tiny miracle that contains everything it needs for life. However, once the outer coat has been broken down, the emerging seedling is very vulnerable until it has formed sufficient root to acquire moisture and nutrition for itself. At this stage it is vital that it isn’t allowed to dry out. Here are some ways to ease your seedlings through this delicate stage:

*Partially cover seed trays with polythene or glass (allowing some air flow) to retain moisture.

*Gentler forms of watering such as using a watering can with a rose, overhead irrigation, drip lines or capillary matting are
preferable to using a garden hose on young plants. (Of course, the more vigorous plants like peas and beans will withstand much more than a delicate cactus seedling.)

6) Did you know that keeping your young plants up on shelving isn’t just for convenience? It also serves to protect them from pesky mollusks. Yes, slugs and snails. They love damp, dark corners to hide in during the day, saving their energy to come out and graze all night. So, keep your root babies as far away from them as you can!

Best of luck to everyone who is setting out to sow seeds for the first time or the 50th time!

February- Is it Spring yet?

As the days start to get longer, a new season is here and signs of life are starting to appear all around us. The sight of snowdrops and daffodils remind us that the years march on regardless of what else is happening in the world around us.
On beautiful days when the sun gives that early spring glow we can feel that the year has turned and are tempted to sow something. The reality is, though, that we can still have plenty of wintery weather ahead of us at this stage and it is too early to start anything without protection.
This is the time of year where a greenhouse really shines. As the sun comes out, there is a bit more heat and gentle growth in your glasshouse. With a heated seed bed, you can begin to start your tomatoes, peppers, lobelia, lettuce, onion or pea plants. If you are into bedding plants, you can start lobelia, salvia or sweet pea. Electric heaters or frost protection fleece will help protect your young seedlings from the elements even further.
It is also at this time of year that having a well-built glasshouse really pays off. There is nothing as discouraging as seeing all your young plants destroyed by a toppled greenhouse after a windy night.
That is why our Griffin and Janssen greenhouses are built to last and withstand the unpredictable Irish weather to give you peace of mind.
So enjoy the season and being one step ahead of the elements!

January- A Time to Plan

January is a quiet time in the garden and an ideal opportunity to take a break. However, it is also possibly the most exciting time of the year because it’s time to plot and plan for the coming year. When we make plans, we are filled with hope and excitement. The plants, flowers, or vegetables that we plan to grow are always perfect in our plans. We all know the best of plans can go a bit awry at times but looking forward to a new season is always exciting!

Some people don’t plan as much as others. Your year may be informed by an impromptu garden centre visit and what catches your fancy there. And that is, of course, how we discover new things and embark on new journeys. But planning has its uses, too.

First, I would look at what it is you wish to reap from your greenhouse or garden. Is it flowers? Your favourite salad items? Something exotic? Make a list of what you would like, and then check to see if it is viable to grow here. The beauty of a greenhouse, especially with extra treatments such as a heated bed, frost protective fleece or shade netting, is that the possibilities are greatly increased. Then it is time to look for seed or planting material. You may be able to source them locally, but there is also an astonishing variety of seed available online. You could wow your friends and neighbours with unusually coloured varieties of tomatoes, French beans, courgettes or even strawberries that you would not find in your local supermarket. There is nothing like salad leaves, spinach or sugar snap peas that have just been freshly harvested from your own glasshouse. Fresh bouquets of aromatic sweet pea or carnation on your table are a luxury you can easily enjoy with a bit of foresight.

Don’t forget to look at the final size of what you are going to grow, including the height. Also, some plant combinations make better companions than others. For instance, tomatoes work well with garlic (to repel aphids) or basil (to improve flavour) but won’t thrive as well next to fennel or kale.

So, it’s time to get out your pen and paper, plot out your area and start dreaming! Then make your dreams a reality. Life is an adventure and so is gardening!

Continue reading “January- A Time to Plan”

Buying Seeds – horticulturalist Peter Whyte gives some advice

If you order your seeds early for the coming gardening year, you can beat the rush later. You won’t have to wait for delivery and lose good growing time, and you will have your pick of the available varieties before the popular ones sell out. Check the catalogues and online websites, but also support your local shops and garden centres if you can. Use your notes from past years to guide you: what varieties did well or poorly? Did you have any gaps in your harvest from your tunnel or glasshouse? Try something new every year; a different variety may have better flowers or produce fruit or vegetable crops of better quality than your usual one, or a new vegetable might become a favourite.
Check whether the seeds you are buying are F1 varieties. These are raised by crossing two inbred lines of plants so that their seeds will grow fast and well. If you try to save seeds from them for the following year the resulting plants will be all different and many will be poor, so you have to buy fresh seed every year. F1 plants are also very uniform, and if you want a few lettuce plants for your own use you may not want them all maturing together. In either case, you may do better with traditionally produced, open-pollinated seed varieties.
Once your seeds arrive, store them immediately in a dry, dark and cool but frost-free place. If you leave them on the garden shed windowsill they may be killed by frost or the sun’s heat, or fooled by dampness into false starts at germination that use up their food reserves before sowing. And, if you saved any seeds yourself, make sure they are in clearly labelled packets!

Garlic

Garlic has many health benefits, and growing our own is easy when you know how. Homegrown garlic has only the chemicals you apply, and you can eat the leaves and flower-stems when they are young. Planting garlic in a tunnel or glasshouse now can give you bigger and earlier bulbs than outdoor crops, but even starting a crop in modules or pots under cover and planting it out later gives some benefit. It stops the birds pulling them up too.

The ideal soil for garlic is light, well drained, moderately fertile and neutral or alkaline. Wet sticky clay can rot the bulbs and very rich soil encourages leafy growth at the expense of the bulbs. A good supply of potash helps, so dig in some wood ashes before planting. Garlic needs a long, cool growing season and a cold spell to stimulate maturity, so autumn planting is ideal. However, you need to choose your material carefully.

Do not plant shop-bought garlic and expect a decent crop; you may be lucky but it is sold for eating rather than planting and may be treated to inhibit growth, or carry plant diseases that will persist in your soil for many years. Get disease-free sets of varieties suitable for autumn planting from a garden shop or centre. Gently split them into cloves, and plant the bigger ones 2-5cm deep into the soil 15cm apart, in rows about 30cm apart, with the pointy end up and the flat base down. Plant the small cloves close together to produce leaves like chives. Water the crop lightly and let it dry out between waterings to prevent rotting. Dig up the bulbs gently when harvesting, and avoid pulling them. They bruise easily and then will not keep. Dry and store them in a cool, airy place.

Growing Basil in Ireland

Basil is easy to buy from the shops, but you can grow a wider range of types yourself at a lower cost to you and the environment. The type sold in non-returnable pots is usually sweet basil suitable for salads and pesto, but there are also cinnamon and lemon basil, varieties with purple leaves that look great in green salads and spicy or liquorice-flavoured Thai varieties that combine well with Asian food.

Basil is a fast-growing, tender annual that needs lots of light, heat, and water. Being very sensitive to cold, it is an ideal candidate for tunnels and glasshouses, especially in our unpredictable summers. It improves the flavour of tomatoes when served with them, and some say that it also does so when grown with them. It grows best in well-drained acid or neutral soil. Sow a succession of crops, but just a couple of plants each time is enough for regular use unless you want extra for pesto. Either sow them in cell-trays or in situ in the greenhouse soil, thinning them to single plants as soon as they are big enough to see. Use scissors to avoid root disturbance. Thin or place the plants to about 30 centimeters apart. Harvest leaves as soon as the plants are about 20 cm tall, by cutting off shoot tips. Leave on the lower leaves until you discard the plant; they will produce the food to grow new shoots from the lower side-buds. Even if you need no basil, cut off the tips to prevent flowering (which makes the leaves bitter) and encourage fresh sprouts to grow. Surplus leaves can be either frozen for later use or composted, and the flower-buds are edible too.

Sweetcorn

You can grow sweet corn outdoors in a good summer, but for a more reliable crop you need a greenhouse. April sowings are best done in pots but in May and June seed can be sown directly into its final position. Sow one fresh seed about 1cm deep per tall pot of free-draining compost: if using older seed sow multiple seeds per pot and single the seedlings later with a scissors. Keep the compost warm and not too wet. Sweet corn roots go very deep and do not tolerate confinement, so plant out your crop as soon as possible. Choose the tallest space available, although it won’t matter if the tops are bent over at the roof. Dig large planting holes 30cm apart in a square block to aid pollination. Fill them twice with water and add in some compost when planting; corn needs plenty of water and feeding.

If space is short, you can plant corn between rows of greens due for harvesting soon. Keep watering and feeding. When the sticky tassels appear on the lower female flowers, shake or tap the plants gently each day to shower pollen down from the male flowers above and ensure well-filled cobs. Cross-pollination gives poorly set and less tasty cobs, so if growing different varieties try to plant them as far apart as possible. The cobs mature close together, so sow later crops to extend the season. The cobs are ripe when the tassels darken and wither, and punctured kernels leak milky fluid. They dry up and get starchy very soon, so harvest them promptly, cook then immediately for four minutes in boiling water, and enjoy.

Cold Frames

Cold frames are four-sided boxes with transparent covers sloping towards the sun. You can buy readymade ones or easily make you own with new or recycled materials. They are out of fashion nowadays because more people have tunnels or glasshouses, but still very useful.

You can use cold frames to hold plants for which there is no room in your greenhouse just now. They are good for hardening off vegetable plants or half-hardy annuals raised in the greenhouse before planting them out in the garden. You can sow seeds earlier than possible outdoors if greenhouse space is not yet available, or quarantine new plants, or keep plants that need warmer or cooler conditions than you have in the greenhouse. Cold frames are good for rooting cuttings, or warming up water or potting compost before use. If you need an extra degree or two of frost protection for plants inside the greenhouse, you can put a lightweight cold frame over them for the night.

Cold frames are best placed near your greenhouse for convenience, and facing as near south as possible. Their south walls should be low enough to let in the sun. To ventilate, prop open the downwind side of the top cover. If you raise its upwind side, a gust could flip it off, and if you slide it the gap may be on the wrong side letting in chilling draughts. It is harder to control their temperature due to their small volume, so you must anticipate the day’s weather and ventilate accordingly, closing the cover at night. If you expect hard frost, lay a quilt of weighted bubble-wrap or sacks stuffed with leaves over the cover for extra insulation. Water plants in the mornings to let the leaves and soil surface dry off before night.

Greenhouse Ireland have developed a new range of Cold Frame lids. Details on request.

Electricity

As the days get shorter and colder, you might think about bringing an electrical power supply to your tunnel or glasshouse. Electricity can power lights, heaters, soil warming cables, propagators and climate controllers, letting you grow a wider range of plants over a longer season. But it’s not just a matter of running an extension cable out from your house; domestic cables and fittings are neither shockproof nor waterproof enough for safety in greenhouses. Electricity and water are a lethal combination. If you only need working lights you could use wireless battery or solar-powered lights with high-efficiency LED bulbs. If you already have a low-voltage garden lighting circuit nearby you could take a short spur off it, provided it can handle the extra load.

If you need mains power, you must get a registered electrical contractor to do the specialised wiring work. At the least, the supply from the house should be through Steel Wire Armoured (SWA) cable buried at least 50-60 centimetres underground with warning tape above it. It should pass through a Residual Current Device (RCD), which monitors the flow of current out from the distribution board and back and trips instantly if they are not the same (i.e. current shorting elsewhere). All sockets, plugs and fittings should be of heavy-duty industrial type with a much higher Index of Protection (IP) rating than domestic ones. They are not cheap, but neither is human life!