Welcome to another edition of Nigel's Gardening Hints and Tips! In this article I talk about tree ferns, which are a must for any gardening enthusiast. Also, don't miss out on my top gardening tips after the tree fern section. Have fun!

There are various different species of tree ferns, the most common being Dicksonia antarctica which is the one that this article will be based upon. In my opinion this one is the most interesting and exciting of the tree fern family.

Tree Ferns in the wild must be the most magnificent sight in plant culture, from the delicate fronds to the tree trunk shape of the plant, they are an amazing living organism of the plant world.

The most interesting part of a tree fern is the main root section which is intertwined into the main trunk-like structure of the fern. This is followed by the delicate fronds which grow from the top uncurling outwards to freedom!

My first encounter with tree ferns was on a day trip to my companies nursery which is located down south in the United Kingdom (UK). This was where most of our plants were grown or imported to when I worked at the garden centre a number of years ago.

I can always remember the visit being on a hot sunny day, and as we turned the corner in to a sheltered area at the back of a large potting shed, I stood there amazed.

There were approximately 20 to 30 tree ferns, from one foot to about ten feet tall, all Dicksonia antarctica which is the main species that grows reasonably well in the UK. The nursery manager told us all about them, and I was interested to find out that they had been imported from the forests of Australia. Each one had to possess a passport to get through customs, which consisted of a certificate, and a personal tag nailed onto the root trunk. This was, and still is, to prove they are genuine and not removed from the wild illegally. They also had to go through a variety of quarantine procedures once in the UK, before being allowed out to the nurseries. This was a long procedure.

Approximately two weeks after the visit, we started to see them for sale in the garden centre; many took a lot of moving with mechanical equipment as they were so heavy. However, there were smaller ones which sold more quickly, mainly because they were within customers' budgets. The taller they were, the higher the price and many people didn't want to risk spending £200 plus in case they died! Prices have increased phenomenally now, but when I worked there the usual rule of thumb was £30 per foot of tree fern.

The big monsters made a show-piece in my displays, and they sold quickly after I had just added the finishing touches. At the time I thought: how dare customers ruin my displays and buy the stock (just to pay a small pittance of my wages)!

Anyway, I hope that this article gives you the enthusiasm to buy a small tree fern, or perhaps you already own one and just need a little guidance. Follow my advice, and you should have a healthy and delightful fern to give you a main focal point in your garden for a long time to come.

If you are thinking of buying one, my advice is: buy the biggest you can afford as they only grow about one inch a year (two and a half centimetres)!

Tree ferns have been around for well over 300 million years, and were probably brushed past by dinosaurs - how amazing is that! The Victorians created special greenhouses which they called ferneries. It was an exciting hobby for them, which made a change from the normal trees, plants, and vegetables within their gardens. A name was invented for their hobby - Pteridomania.

It started in the UK during the 19th century. Boats coming from Australia carrying cargo, would use the heavy trunks of tree ferns as ballast to keep the boats steady. When they arrived at dock, many crews would simply throw the ballast overboard. This happened in Falmouth, Cornwall except one day they were fished out and planted, which created a lovely abundance of green fronds growing from the top of the fern and caused many a talking point in the community.

After a while many people began growing tree ferns and they soon became very popular. However, later in the 19th century, rules and regulations changed and strict procedures were carried out to avoid them being illegally removed from the wild.

It feels strange that something exotic as these grow in forests of other countries, while in the UK they are a rare and exciting thing which takes a lot of care and attention.

Tree ferns can be grown in pots or simply planted in the ground. They require a damp partially shaded position, with protection from harsh frosts and cold winds. If you do decide to plant directly into the ground, a humus-rich neutral to slightly acidic soil is best. Many people prefer to plant them in pots so they can be moved into a shed or garage during the winter time to give them that extra protection.

Most tree ferns are brought in containers, however, as they have no underground roots it can make transporting them home quite difficult. I can think back to many a time when we had to battle to get a large tree fern in a customer's car. The compost used to anchor it into the pot would end up spilling out into their car boot, and sometimes the actual tree fern would come out of its pot. If the customer was not informed that the roots were the actual trunk, they would look horrified thinking that it had rotted off!

Firstly, the ground: If the climate conditions are suitable (as described above), you can plant in the ground making sure to mix in plenty of humus rich fertiliser before planting (e.g. well rotted manure, leaf mulch or compost). It is best to plant to the same depth they are planted in the pot, but if they are bought without a pot then it is best to put them in the ground approximately 9 inches (23 cm) deep but this does depend on the size of the fern. The usual rule of thumb is to plant them deep enough so the fern is stable, but it is always best to stake them for the first season (12 months) until they settle into the ground.

My personal favourite is to either keep the tree fern in its original container, or pot it into a nice decorative one of your choice. It is best to purchase a crock pot (if funds will allow), as these are heavier and should prevent them from tipping over. You will find that tree ferns will normally come in plastic pots which is, of course, down to cost of transportation, weight etc.

When choosing a pot, make sure that it is no more than 2 inches bigger in diameter than the pot it is currently in. This is because the compost at the bottom will go stale, resulting in possible rotting of the trunk as well as a possible smell!

It is best to make sure there are adequate drainage holes, and that the pot is raised by using pot feet to ensure it does not crack during any frosty weather. Also, placing grit or broken crock at the bottom of the pot will help with any drainage problems and ensure water will drain freely.

You need to use a fairly heavy compost, the multi-purpose types are too light and could cause the pot to fall over during windy weather. I have always recommended using a loam based compost such as John Innes No.3, which will keep the fern more stable and prevent leaning if it is quite tall.

As with all plants, they will benefit from a watering after planting. Tree ferns are always watered from the top using a sufficient rose on the end of a watering can, or a spray lance on the end of a hose. Water down the top, and also the sides as these are where the main roots are. Never allow it to dry out. Surprisingly, you can never over water a tree fern. Tree ferns benefit from rain water.

Once a year, apply a sprinkling of fish, blood and bone around the base. If you water it in afterwards, this will help to keep your fern looking healthy. This is not essential, but can be more as a yearly treat!

The actual trunk and root system will grow approximately one inch (two and a half centimetres) per year, producing anything up to 30 fronds. This is the main reason they are so expensive to buy, along with the import costs. It is definitely worth it, as they are lovely exotic looking plants.

Be warned though, tree ferns have a brown hair-like surface structure which can stick to clothes and will take quite a bit of brushing off! This only comes off the main trunk, but if you brush past it then it can be quite embarrassing if you walk up the road with brown hairs down your back!

Now, Winter time: If you live in a warmish area, such as south of the UK like London or the south west such as Cornwall, then your tree fern should be fairly safe against frosts. However, as the last few winters have been unpredictable it is best to put straw down the centre of the fern and carefully wrap the whole thing in hessian, fleece, or even using straw in a wire cage structure. This is probably best done even if you do live far south, as they are too expensive and delicate to lose.

If you have it in a pot and it can be moved safely, then move into a frost free place such as a shed, garage, or other sheltered area. I would still wrap it in a double layer of fleece as an extra precaution.

This procedure is needed mainly during cold spells. The weather is constantly changing so I cannot give a precise time of year to cover and uncover. It is best to keep your eye on the weather forecast, the danger being mainly when water freezes in the centre of the trunk which causes rotting.

You will see the fronds starting to die off, and this is usually a good indication that the season is coming to an end. Most people leave the fronds on which gives extra protection during the winter. They should eventually drop off, before new green shoots appear from the centre crown in spring. However, you can snip them off when they die if they are too long to cover.

If possible, unwrap and check once a week for any insect damage. It is worth leaving the wrapping off during any sudden warm days to allow the fern to get a breathe of fresh air!

In the past, there has been much debate whether or not importing tree ferns is a good thing. This is because many different insects hide in crevices of the ferns which can introduce new pest life to the UK.

DEFRA (Department for Environment Food and Rural Affairs) regularly check tree ferns before allowing them out of quarantine to nurseries and suppliers. If many of these insects are regularly found, the ferns can lawfully be destroyed or sent back to the exporting country.

Many of the tree ferns came from forests in Australia that are being destroyed for development, so if they were not sold on then what would happen to them? They would most likely have been destroyed or sold within the same country which means that Europe would have little imported, except ones grown in specialist nurseries abroad. This would be a time consuming job, as tree ferns are very slow growing.

There was a long debate over this in 2004, and after finding numerous foreign insects in one tightly packed batch, the suppliers abroad abandoned the export of forest grown tree ferns as the insects were clearly identified as forest creatures.

Many tree ferns are now grown in nursery environment conditions abroad, the drawbacks being that tree ferns will not be as mature but it is the best option to avoid some of the predators taking up residence in this country. This does not completely eradicate the problem, as they can still come over on other plants and also nursery grown tree ferns if the fumigation techniques are not effective.

Nurseries and suppliers in this country are pressured to regularly check stock for any sign of foreign insect attack, as little eggs can bury deep inside the trunk and are not always picked up on in the quarantine branch. They must inform DEFRA if they find anything unusual or unidentifiable¹.

The main problem I have come across are the edges of the fronds turning a black or brown colour. This can be due to a number of problems:

• Exposure to direct sunlight which can scorch the leaves - this is easily rectified by moving to a less sunny position. They like a partially shady position, but can survive in full shade like they often do in the forests of Australia and other places.
• Not enough water - They should never be allowed to dry out, except when they are fully dormant during the winter time (according to weather conditions). They like a damping down by using a sprinkler lance on a hosepipe. Water down the top, and also the main trunk as this is where the roots are growing. This should be done once a day during the summer time, unless it is raining or snowing!
• Cold winds - The common tree fern (Dicksonia antartica) can survive in temperatures as low as -10 C, but it is a great risk to leave them uncovered during the winter time. Cold winds can turn the edges of the fronds black if the weather suddenly changes, and it can also cause any water inside the trunk to suddenly freeze which can cause rotting. The best positioning is a shady sheltered position, which is away from frost pockets and main central winds. I know that this is not always easy to do, however, the main thing is to make sure they are covered during winter time. This can depend on the climate you live in e.g. the further down south you are, the warmer it should be, but I would still cover them!

Tree ferns are not prone to insect attack, but there have been reports of thrips in the past. I would not recommend the use of insecticides or pesticides as the fronds of tree ferns are sensitive to many chemicals. If the problem does get severe, the best solution would be to cut off and destroy the fronds by incineration.

If your tree fern is in a container, I would recommend repotting approximately every five years as the compost can go sour which can cause odours and cause the trunk underground to become unhealthy. It is best to replace with fresh compost and if you do change the container then choose one roughly the same size. You can choose one slightly larger, but no more than two inches (5 cm). You may need to temporarily stake it until the trunk settles in (according to size). This is best achieved by knocking a stake into the ground and using a large adjustable tree tie to steady it. If you have the pot on a patio or other hard surface, then you could tie it loosely to the wall or fence by using appropriate fixings. Do not tie the trunk too firmly, and use something with a soft coating on to ensure it does not do any permanent damage. Once the tree fern feels fairly stable, and does not move around in the pot then these tie fixtures can be removed.

The larger mature tree ferns can be very heavy to handle, especially if they are in crock pots. If moving or repotting, then get help and do not try to move them yourself like I have done in the past!

When handling the beasts remember to wear gloves, and be careful that the hair like material off the trunk does not blow into your eyes. If it accidentally does, then use a suitable eye wash solution and obtain medical advice if symptoms persist.

If you hurt your back while moving a tree fern, get a massage!

That's all for this time, but before I go have a look at the top tips of the fortnight:

• If you grow cabbage, you are likely to suffer from the annoying cabbage white butterfly. By planting garden mint near to the bed, this will repel them and send them elsewhere!
• Apart from the smell and brightness of Marigolds to keep whitefly at bay, they also have another use. The roots give off a chemical which deters eel worm from damaging tomatoes, and even many other plants.
• Planting sage by your carrots should protect them from the carrot root fly. They do not like the smell of sage, and also it disguises the carrot smell which means they fly away thinking that no carrots are even there!
• If you plant purple foxgloves next to your apple tree, they will help to increase the resistance to disease and create a happy apple tree which should provide you with lots of juicy fruit!
• A patch of nettles is a must for any garden, as they give valuable nutrients to the soil and help to deter mildew and other pests and diseases. Nettles also have lots of other uses!

Happy Gardening My Friends!

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