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Chicken wire/reinforcement mesh in a home-built greenhouse

Question:

Is it very detrimental to use chicken net/reinforcement mesh instead of glass/plexiglass in your home-built greenhouse for greens, not for tomatoes just greens?

Best wishes
Ann Marie from Denmark

Answer:

Hi Ann Marie,
I understand your question in the way that you want to make a greenhouse out of chicken wire or reinforcement mesh. You can easily do that, but it must be because you think it is beautiful and it can definitely be. There are greenhouses that are built from a lot of lists and are called shadehouses. In Sweden, I have seen houses where the framework is built of round iron, which reinforcement mesh is also made of.

If you want to do it to get a decorative element, then it is a great idea. If you pull a net over, you are free of almost all pests. However, it steals some light, but it only needs to be netted during, for example, the time the garden whites lay their eggs. Otherwise, vegetables thrive, as you know, in the open air and actually not very well in the greenhouse. You can also easily grow tomatoes in the open air. I do not grow mine in my greenhouse, but in the kitchen garden, and they yield delicious tomatoes. It just depends on the sort.

Raised beds with windows of plastic or old windows laid on top are also a solution if you want early vegetables. Here too there are many models, if you e.g., google the word garden frame. Pipes put in arches with a plastic sheet over also work fine, or with an insect net.

Caterpillars: usually it is early enough to cover around Midsummer Day, as it is usually only around the 1st of July that caterpillars really appear. You can find a few larvae of large garden whites, in May and June and a few more in July, but the number does not culminate until August, and usually the last half of August.

Previously, one could buy a pesticide that killed the caterpillars, but it is not in the trade anymore. Otherwise, you have to inspect your plants and squeeze the eggs to death. If you have more questions, you are very welcome to ask.

Get well into the spring.

Best wishes
Lars Lund

Sprouts that bend

Sprouts that bend

 

Question:

Dear experts,
I often find that many of my vegetable seeds bend after germination, even though they are regularly irrigated and stand in a window ledge. At approx. 22 degrees room temperature. 

What am I doing wrong? They often bend just a few inches from the ground.
Hope you can give me answers to this mystery that I experience every year.

Best wishes
Jan from Denmark 

Answer:

Dear Jan,
When I see the long stems, I immediately think: they lack light to a degree. In addition, they could very easily be exposed to something called root rot. Root rot is caused by several different species of soil-dwelling fungi. They attack the root collar and roots of herbaceous plants, which grow under adverse conditions, that is, too high humidity, compact and cold soil, which is not good. On the other hand, vegetable seeds should not be too hot. 10-15 degrees is best.

The attack of root rot is typically seen by a dark staining where the stem has contact with the ground, slightly below and slightly above. Eventually they dry out and become thread thin. The transportation of water becomes cumbersome, so the plant withers and dies. You can remedy this by partly using potting soil that has the right mix of gravel, that drains, and soil. Irrigate from below so the water is absorbed into the soil and use vermiculite in the top thin layer, it keeps the root collar dry. So, in your case, I think it's a mixture of lack of light and proper drainage in the ground.

Best wishes  
Lars Lund

A mistletoe in an apple tree

Question:

Dear Experts,
I have a large, very old apple tree in my garden. About 10 years ago I spotted a small cluster of mistletoe among the branches, and I now have about 20 large bunches of mistletoe in the one tree. Is this a problem for the tree, as I’ve read that mistletoe is a parasite?

Best wishes
Torben from Denmark

Answer:

Hi Torben,
Thank you for your question. Mistletoe is a semi-parasite, which means it makes its own food from its own leaves, just like other plants, but because it can’t grow in the ground it needs to live on a host tree where it taps into the tree’s water and minerals. In general, mistletoe won’t kill a healthy tree but it can weaken it, and if the tree is old or sick mistletoe can cause problems.

The berries are spread from tree to tree by birds – the sticky flesh means the mistletoe seeds end up stuck to the branches where they germinate. Mistletoe particularly likes apple trees and it’s mainly found in the south and west of the UK, with high numbers of orchards.

Mistletoe can become a problem for trees if the bunches become too big and heavy, causing branches to snap, which can in turn make the tree vulnerable to diseases. Mistletoe can be pruned, in fact in the apple orchards of Worcestershire and Herefordshire they harvest the mistletoe and sell it at mistletoe markets in the run-up to Christmas.

A few groups of mistletoe on a healthy, large tree shouldn’t be a problem, but any more and they will have an impact on the growth and health of the tree. It’s therefore best to cut back the mistletoe growth in winter, it will however regrow, so you will need to remove the branches of the tree to reduce the number of mistletoe growths. Once you have a manageable number of bunches, cut back the growth every couple of years and check branches for new seedlings that have sprouted, removing these when you spot them. If the tree is tall you may need to get a tree surgeon to do the work.

Best wishes
Lars Lund

How to use a Plant Spiral

Question:

How do you use the Juliana plant spiral?

Best wishes
Leif from Denmark

Answer:

Hi Anna,
The plant spirals hang from the roof of your greenhouse and are great for growing vegetables, such as tomatoes and cucumbers, offering support for their stems as they grow. Each spiral is made from an inner aluminium tube that’s covered in green plastic so that they’re strong and durable. The spirals look like springs but they’re not as flexible, and once you’ve pulled them you can’t shorten them, so slowly extend them to the required length – you may need an extra pair of hands.

Best wishes
Greenhouse Forum

Moving a greenhouse

Question:

I’m moving house and I wondered if you have any tips on how best to move/transport my greenhouse?

Best wishes
Susan from Denmark 

Answer:

Hi Susan,
Thank you very much for your question. All the glass will need to be removed. If the glass is held in place with mounting strips remove these – you can save them or buy new ones. If the glass is fitted with clips, carefully remove these, popping them in a plastic bag or storage box. If the glass is fixed with silicone then use a knife to remove the glass. Remember to buy new silicone for when you come to rebuild the greenhouse. Pack the glass in a sturdy box, making sure that it can stand upright and that the glass is securely packed so that it can’t move about inside the box.

The greenhouse should then be removed from the foundation. It can be transported in one piece, just without the glass, on a flatbed truck or divided into sections and put in a van. It’s important to make sure the frame doesn’t move too much during transportation as the frame can twist out of shape. Make sure you keep hold of all the fittings and store safely for the rebuild.

The other option is to completely dismantle the frame. Make sure you mark up each piece so that you know where everything needs to go when it comes to reassembling it.

It will be easiest to have a new foundation made for the greenhouse so that it is securely anchored to the ground.

Of course, you could save yourself the time and expense of moving an old greenhouse and treat yourself to a new model for your new garden. Perhaps this is the opportunity to upgrade to something bigger or to buy a model that suits your new home and garden.

Best wishes
Greenhouse Forum

Washing Vine and Peach stems

Question:

Why is important to wash the stems of grape vines and peaches?

Best wishes
Inger From Denmark

Answer:

Hi Inger, 
Thank you for your question. Scale insects can attach themselves to the stems of plants like vines and peaches. These pests suck the sap from the plants weakening their growth, so it’s a good idea to keep an eye out for these insects – they look like small, brown shells. Check the stems from late winter onwards and use a cloth dipped in rubbing alcohol, also known as surgical spirit, to wipe away any scales. With grape vines it’s a good idea to peel away any loose outer bark to expose any scale insects and other pests which might be hiding underneath.

Best wishes
Lars Lund

Greenhouse Stability

Question:

I’ve moved into a house with a greenhouse in the garden. The floor of the greenhouse consists of slabs with some gravel underneath. I’d like to remove the slabs and put fresh soil there so that I can grow directly into the ground, but my husband is concerned about the stability of the greenhouse. Is it OK to remove the slabs?

Best wishes
Natalie from Denmark 

Answer:

Hi Natalie,
If the greenhouse is sitting on a cast base it should be safe to remove the slabs. However, you should be aware that the foundation may need to be supported, so it’s a good idea to remove a few slabs at a time and provide support where the slabs have been removed. Repeat until you’ve removed all the slabs and supported the whole structure.

Best wishes
Klaus Bisgaard Lillesø
Quality manager, Juliana Greenhouses

Identifying an Unknown plant

Identifying an Unknown plant

 

Question:

Our daughter has this plant growing in her front garden. It’s about 75cm tall and produces flowers with lots of yellow pollen, which the wasps and bees love. What is its name?

Best wishes
Palle from Denmark

Answer:

Thanks for your question, Paula.
It’s a slightly blurry image, but it looks like common ivy (Hedera helix). It’s a clinging climber which can also be grown for groundcover. It flowers in autumn often when other flowers have gone over, so it’s great for providing bees and wasps with a late source of pollen and nectar so that they can build up their reserves for winter. Be aware that the plant is poisonous and can cause allergic skin reactions.

Best wishes
Lars Lund

Propagation of Artichokes

Propagation of Artichokes

 

Question:

I planted a couple of artichokes in the spring and they have grown quite tall and provided a good crop. The largest plant looks like it has divided into three separate plants at the base. Is it possible to propagate it and how should I go about this?

Best wishes
Tove from Denmark

Answer:

Hi Lisa,
Yes, these are suckers from the root base. Artichokes can be propagated from these suckers when the suckers are about 20cm tall in November or April, using a sharp knife or spade to separate the shoot from the parent plant. Pot them up into individual pots filled with a loam-based compost. Artichoke plants will be productive for several years but after this it’s a good idea to plant new plants.

It’s also a good idea to mulch the base of artichoke plants in autumn, using a thick layer of straw to protect them from the cold.

Best wishes
Lars Lund

Plants and light

Question: 

Can plants get too much sunlight in a greenhouse?

Best wishes
Christine from Denmark 

Answer: 

Hi Christine, Thank you for your question. Yes, it is possible for plants to get too much light when grown under glass. Plants have evolved to cope with the light levels in their native habitat, so plants from the desert tend to have thick, fleshy leaves which can cope with high levels of intense light and heat. Whereas plants from cooler, more northerly locations will have adapted to make the most of the available sunlight. From May to mid-August it’s easy for plants in a greenhouse to overheat and for their leaves to be scorched by strong sunshine that’s intensified by the glass. Providing sufficient ventilation on hot days by opening vents and doors can help. You can also attach blinds or shade netting to the outside of the greenhouse or apply shade paint to the glass to reduce the intensity of the light.

Best wishes
Lars Lund

Lemon tree loses its fruit

Question: 

The fruit on my lemon and orange trees have fallen off. Why has this happened?

Best wishes
Kate from Denmark 

Answer: 

Thanks for your question, Kate.
Citrus fruit can take almost a year to develop to full size, and most cultivars form too many fruit for the size of the plant. These will often be naturally shed by the plant, but it’s a good idea on young plants to thin the number of fruit in each cluster to one.  

Don’t over water in winter and keep the plant in a pot that is not much larger than the root ball of the tree. Use a specially formulated citrus feed – high nitrogen from spring to midsummer and a balanced fertiliser between midsummer and autumn.

Best wishes
Lars Lund

Fungi in the Greenhouse

Question: 

How do you avoid fungi in your greenhouse?

Answer:

There are, generally, always moulds and fungi present in humid environments. Good ventilation is key, opening vents and doors to provide air flow. It’s a good idea to do this on mild winter’s days too, just for 10–15 minutes and make sure you remember to close the windows and doors.

Good plant hygiene is important throughout the year, making sure any yellowing or dead leaves are removed promptly, and dispose of any dropped fruit.

Overcrowding is a factor, so make sure there’s plenty of space in between plants for good air flow.

Take care when watering to water the compost in the pots and avoid splashing the foliage as this can encourage mould to grow.

Best wishes
Lars Lund

 

Toad in the greenhouse

Question: 

I have a toad in my greenhouse, what should I do with it?

Answer: 

Toads in greenhouses are not uncommon. They like the humid environment and to eat the slugs and snails that inhabit the nooks and crannies of the greenhouse. They aren’t doing any harm, in fact they’re a natural pest control, so leave it alone. It’s worth bearing in mind that there are toxins in the skin of toads that are poisonous to pets, and it’s a good idea to wash your hands if you come into contact with one.

Best wishes
Lars Lund

Larvas in my Strawberry plants

Question: 

I have small, green grubs in my strawberry plants that have eaten the leaves. What should I do?

Answer: 

These sound like the strawberry sawfly. They pupate and overwinter in the soil, so in April and May check the undersides of leaves for eggs and larvae and remove them by hand. After the plants have finished fruiting cut back all the foliage, leaving just the crown of the plant, and clear away plant debris.

Best wishes
Lars Lund

Column

In the column, you can, as a reader, ask our experts questions that can't be found on the blog. A couple of times a month, we choose questions to be published, and the lucky one will receive a small gratuity as a thank you. Your question will always be answered, even though it is not published. 

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