Tuesday, May 27, 2008

Old crocks? Not on my balcony ...

Open any book on container gardening, and you'll soon come across a stern admonition about always adding a layer of old crocks to the bottom of your containers to assist drainage. If not, the received wisdom goes, the drainage holes in the container will get blocked by soil, the soil itself will get waterlogged and your plants will die.

Sounds logical. So why is it, I always wondered, that whenever I get plants from the garden centre there is never, but never a layer of drainage material. There may be perlite of sand or something mixed into the potting compost, but at the base nothing. And yet the plants are healthy, happy and show no sign of being waterlogged at all.

So I was intrigued to find
this article in the Horticultural Myths section of Linda Chalker-Scott's website. Chalker-Scott, who is an Associate Professor of Horticulture at Washington State University, argues that far from aiding drainage, the broken potsherds, gravel etc usually used will actually prevent it, and leave the soil more rather than less waterlogged.

According to Chalker-Scott this has been proved by a number of studies. Annoyingly she doesn't provide references, so there's no way of checking. But I thought it would be fun to try an experiment and see what happened.

So today we have the great Balcony Garden Drainage Material Experiment. No claims to being scientific, but here's how it goes. Two identical 10cm pots, one with old crocks and large clay granules in the base, the other without. Both are then filled with the same potting compost, and the same amount of water is added - enough to more than waterlog the soil.

The liquid that drains off immediately and after half an hour is measured and, lo and behold is exactly the same.

However, as the whole point is to see how this affects the plants growing in the pots, there's a second stage. Two marigold plants, as nearly as possible identical, are added - one in each pot. I've called them Bill and Ben. Bill is in the pot with crocks and Ben in the pot with no crocks. Over the next few weeks they'll be kept in the same position, receive an equal (though generous) amount of water, and be treated in every way identically. And we'll see what happens.

Who'll grow strongest? Will it be Bill or will it be Ben?

Sunday, May 25, 2008

The first hollyhocks

In May something seems to happen every day. Only three days ago I said that my hollyhocks were in bud but not yet blooming, but look at them now.

I've got about seven plants all together, and as they came from some seeds I collected a couple of years ago, I'm not sure what colours I'll get. But that's part of the fun. I love the delicate pale pink of this one.

These are plants which I sowed just under two years ago. I must have put them in too late in the year for them to flower the following summer - they hardly grew at all last year. But this year they just shot up, although some which I transplanted lost a few lower leaves - I think it may have been rust or a watering problem rather than the move itself. But they're now all where I want them, so at the end of the summer I'll leave them where they are and see how they get on as perennials.

Another plant which is related to the hollyhock (both are part of the malvaceae family) has also just come into bloom - my mallow. It recovered well from the red spider mite attack of a few weeks back and, though it lost a few leaves, is now looking healthy again. The flowers aren't as spectacular as those of the hollyhocks, but they're nice in a delicate sort of way.

The "fight against the mite" is still going on. Although the mallow now seems clear, some of the other plants have been slightly affected. Luckily the weather seems to be on my side - the mites don't like the cold wet conditions we've been having, and that gives me a headstart on them. I've been merciless in ripping off any leaves I've seen affected, and so far things are under control. But it's too soon to feel confident. There's another four months of relentless struggle ahead ...

Thursday, May 22, 2008

Looking good ...

Even if I say it myself, the balcony is starting to look good. I worked hard last weekend pulling out the last of the spring plants - a sad goodbye to my little pansies - and rearranging the containers to emphasise the things which are now at their best. One of the few advantages of balcony gardening is that a lot of the the plants are mobile. Whatever is looking most glorious can always be bang outside your living room window.

Several things, like the pelargoniums and petunias, have been blooming for a while, and whether they were old plants, new cuttings, or bought this year have settled well and doubled in size. Some of the perennials, like the plumbago and the hollyhocks, aren't yet in bloom, but are growing strongly and their foliage is giving the balcony a lush, "full" look. And in a month or so they're going to be great. The hollyhocks particularly are towering over everything else and are full of buds. And lot of the bulbs, corms and tubers which I put in for the first time are now coming through well. This year's experiment are the dahlias, which because of their size had to go into the "container from hell" - a large container in a particularly shady, but extremely hot spot on the back balcony where very little survives. And yet they're doing wonderfully, and are now coming into flower. Probably because the hot weather hasn't hit yet. They're tall enough to find the light, but aren't yet suffering from heat exhaustion. We'll see what happens later.

One of my favourite plants is the lychnis which you can just see peeking through the hollyhocks in the picture above. I had several, but the majority, which were in a different pot, suddenly wilted. I suspect they didn't need quite as much water as the other plant which was in there.

Lack of some decent weather has held back the growth of the annuals which I sowed in March and April - the only disappointment so far this year. Yet again this week we've had torrential rain and temperatures well below usual. As I write there's thunder rumbling around, and this morning the bus even had the heating turned on. Things like the marigolds, which would usually be putting out buds by now, are still in their seed pots while the more delicate seedlings - like the surfinia - are still tiny.

The rain has also knocked down the antirrhinums and made the ivy leaved pelargoniums look a bit straggly, but there are plenty more buds coming through.

I don't like very hot weather, so I'm not desperate for the summer to arrive. But a bit of spring would have been nice ...

Tuesday, May 20, 2008

Agave or Aloe?

When is an Aloe not an Aloe? When it's an American Aloe, or Agave.

Agaves and Aloes certainly look similar, but despite the fact that Agave americana is often called by the misleading name of American Aloe, the two plants are not actually closely related. The agaves are native to Mexico and the southern states of the US and come from the Agavaceae family, while the Aloes are African in origin and part of the family Asphodelaceae.

Why am I bothered? In my last post I described a plant which I'd seen in Barcelona as an aloe, but in a comment, Blackswamp Girl referred to it as an agave. Which got me wondering if I was right.
After looking at lots of pictures on the net, I think I am. But I can see why the confusion arises. There are agaves which look very similar to this, and aloes which are quite different.
What does anyone else think?

Sunday, May 18, 2008


I spent last weekend in Barcelona, where I met up with a friend from Cambridge, whose daughter is at university there under the Erasmus scheme. We had a wonderful time, only slightly marred by the disgusting weather of the first thirty six hours - torrential rain and wind so strong you couldn't keep an umbrella up.

We'd intended to spend the weekend "doing" Gaudi - OK, not the most original thing to do in Barcelona, but the obvious choice when you've never been there before. In the event the weather on Saturday meant that we spent most of the time in coffee bars and shops - but then we hadn't seen each other for a while, so we had lots of catching up to do.

We did manage to see the Casa Mila on Saturday morning, and took in a concert at the Palau de la Musica Catalana in the evening. Although it wasn't designed by Gaudi, it's equally over the top. We heard Rodriguez' Concierto de Aranjuez - which had had its very first performance there in 1940.

But though Sunday wasn't exactly sunny, it had at least stopped raining, and we were able to fit in a few hours sightseeing before leaving for the airport. After a short delay due to an early morning panic when I thought I'd lost all my credit cards, we headed off to the Sagrada Familie. It's odd to see a cathedral still under construction - you feel it should have been finished off five hundred years ago.

Gaudi's work was constantly inspired by nature. There are no straight lines. Everything is curved and reflects something from the natural world : wave markings on the sand, seed pods, mushrooms - even dinosaur skeletons.

So I was really pleased that the weather cleared up enough for us to to go to the Park Guell, a park on a steep hillside (and believe me it is steep) designed by Gaudi and originally intended as a housing estate - though that never actually happened.

Gaudi wanted the architecture in the park to complement the lush, green vegetation, but when you're there it almost seems as if it's the other way round. I was fascinated by the angles of the tree trunks and roots, which emerged from the hillside almost as if they were trying to out-gaudi Gaudi.

Most of the vegetation was woodland, but there were a few bits which had been planted with flowering shrubs. This bougainvillea was just coming out. - though it seemed to have been a bit battered by the rain - and there was also the biggest hedge of plumbago I've ever seen. It was too early for it to have been in flower, but it would be worth going back in midsummer just for that.

I was also amused by these aloes. By chance a couple of days before I'd seen an article on the web suggesting aloe was a great houseplant. Well, this one was certainly growing in a container. But I'm not sure I'd want it in my front room...

There was a colony of parakeets living in the park. When I heard the noise and saw the bright green wings, I thought at first they were the same rose-ringed parakeets that I have in my garden in London, but no - these were different. I think they are monk parakeets, native to South America, which undoubtedly arrived in the park after escaping from captivity, much as the rose-ringed parakeets of London did. They were much happier about posing for photos than our guys though.

Thursday, May 15, 2008

May GBD - Pelargoniums

It's Gardener's Bloom Day again, and the balcony is now looking quite different from last month. The pansies have finished rioting, the summer flowering plants have shot up in height, and the hollyhocks and dahlias are covered in buds but not quite there yet. But the flowers which are dominating this month are my pelargoniums.

I have a love-hate relationship with pelargoniums. They're as common as muck on balconies, and I always feel that perhaps I should be devoting my time and the balcony space to something a bit more original. But if they're common, there's a reason for it - they look so glorious when they're in full flower.

So this year I've succumbed, and the pelargonium collection has grown. I've now got three types - more of the zonal pelargoniums which I've had for years, some new dark pink and white regal pelargoniums, and some ivy-leaved pelargoniums, which I bought last year for the office, transferred here for the winter and never took back.

The ivy leaved pelargoniums were looking pretty tacky at the end of the year, and I had to cut a lot of dead stuff off. But they've sprung back, and now look great from the path outside the house.

I posted about the regal pelargoniums a while back, and Kris of Blithewold left a comment asking if I knew the variety. Annoyingly, I did but have forgotten. I got them at a big flower market which is held here every year, and they were labelled with the variety name. but I didn't write it down and .... I've been hunting on the Internet ever since I got Kris' comment, but can't find anything which is exactly the same.

I've now got zonal pelargoniums in three colours. I took a lot of cuttings from a red variety which I had last year, and those are now thriving. My salmon-pink pelargoniums have been flowering non-stop for years - there hasn't been a week when they've not had at least one bloom - and show no sign of giving up. So I've bought two smaller ones with variegated flowers to keep them company in the container and set them off.

This white pelargonium is another cutting - but I can't for the life of me remember what happened to the mother plant. Anyway, it looks great together with the blue campanula and aubretia in this pot.

Pelargoniums are native of South Africa, and love the hot, sunny conditions we get on the balcony in summer. They don't like the cold, but over-winter well covered with fleece and placed inside the balcony and near the house, where the temperature stays above freezing. They are fairly resistant to pests and diseases, though caterpillars like to munch away at the leaves. The main pest here in southern Europe are the caterpillars of cacyreus marshalli, also a South African native, which was somehow transported to Europe in the late 80s and is now the bane of any pelargonium lover's life. I wrote
this post about it last year.

Monday, May 12, 2008

I'm Having Mitemares...

They're back. Punctually. I'd hoped this year would be different. I thought perhaps the cold, wet April which we had would have at least delayed them a bit. But no. Within days of turning the calendar, this is what I found.

Red spider mite.

Two days before there'd been no sign. My mallow, grown from a collected seed pod, was thriving, and I was looking forward to the first flowers. And then I go out to water, and what do I find - yellow, streaky wilting leaves.

Elsewhere, it can be the most idyllic month in the garden. But here in Milan, May onwards is a nightmare of microscopic red monsters sucking the lymph from my plants. I don't mind caterpillars, and I can cope with scale insects, but red spider mite has me waking on hot summer nights in a cold sweat. They are so insidious. You don't see the first few, but two days later there's a colony and your plants are dying, and if you wait any longer, that's it. They can reproduce from 36 hours old, for goodness sake, and will kill a plant in not much longer. This is what happens if you ignore it ...

What can you do about them? First of all, there are preventative measures. Simply misting the plants helps - pay particular attention to the back of the leaves, where the mites congregate. They thrive in hot, dry conditions - just what we have here on the balcony, and which are found in other enclosed spaces, like conservatories and greenhouses - so increasing the humidity helps. Before the infestations hit, I also spray with a mix of garlic, onion, cloves and cayenne pepper - but it doesn't kill off the mites if they do get a hold. Once that happens, the best thing to do is to pick off all the infected leaves, spray with water (or the mixture above) and wipe down the underside of all the remaining leaves. If you live somewhere where you can get them, there is a predatory mite - Phytoseiulus persimilis - which will clear any that you missed. If not, you may have to resort to spraying.

There are organic sprays on the market which you can use. I can't get them here so I can't comment on how effective they are, but I've spent the last month searching for Neem Oil - supposed not to harm bees and other insects - and according to
this article by the RHS, even the chemical companies produce organic sprays.

If you must use a chemical spray, choose one which specifies that it kills the eggs as well as the adults or you're wasting your time. If you combine it with misting and wiping, you should also be able to keep the amount you use to a minimum.

But even chemical sprays will only work if you catch them early. If not, give up. Pull the plant up and throw it away before the rest of the balcony, conservatory or greenhouse is affected too.

I seem to have caught my mallow early enough to save it. It looks a bit straggly where I've pulled off the leaves, but what remains seems green and healthy. And the infestation doesn't seem to have spread to anything else. But I know this is only the beginning. It's going to be a long hot, summer ...

There is of course another remedy, if you're really desperate. Just take the initial s off the word spraying, and possibly you have the only thing that could really work ...

Thursday, May 01, 2008

Tree in a Cage

(This is the third of a series of posts about a visit to Gardaland, a large theme park in the north of Italy.)

In the middle of Gardaland, there's a nine foot tree in a cage. One of the rides perhaps? Something like the Ents from Lord of the Rings or Harry Potter's Whomping Willow? Both good candidates for a theme park attraction I would have thought. But no, it's a real tree and it's not violent - it's a Wollemi Pine.

The Wollemi Pine is, in the wild, one of the rarest trees in the world. Only about a hundred trees remain (some sources say less), in a secret location in the Wollemi National Park, in Queensland Australia. Why so secret? For the same reason that this one was in a cage - to protect them from people. Who might inadvertently introduce disease, start fires and of course, rip off branches. Well, of course, if it's rare you've got to have a souvenir, haven't you?

It's also one of the oldest living plants. Fossil records date back 200 million years, and at the time the earth was covered by dense rain forest, it was found all over the world. But it was thought to have become extinct together with the dinosaurs.

When I saw the tree, my first thought was that it looked like a bright green Monkey Puzzle tree - it has the same long needles. And in fact, it's from the same family Araucariaceae (wow, I spelt that right first time.)

Discovered by chance in 1994 by one of the Wollemi Park rangers, David Noble (it has been given the official name of Wollemia nobilis), the tree is now the focus of a conservation attempt. While the original trees are being protected, they're now quite widely propagated and you cab see them in various botanical gardens around the world. In Kew Gardens in London, for instance. And even in theme parks.

You can also get one for the garden if you want. You'll need a bit of space, as they grow to over a hundred feet, but one site also pushes them as good container plants, claiming that they "can be maintained in a pot almost indefinitely". Perhaps I'll get one for the balcony. Though as they were only discovered in 1994 and have only been commercially available for a couple of years, I'd like to know how they know.

In the wild they grow in acid soil, and in humid rainforest conditions. However, they are apparently hardy, surviving at a range of -5° to 45°C (that's 23°-113°F). If you're in USDA zones 7-11, you should be fine.

There's plenty on the web about them if you want to know more. Just Google Wollemi Pine. One of the most interesting sites has the tapescript of an Australian Broadcasting Corporation documentary on the trees, called A Green Dinosaur. It's well worth a look. Or click here for a list of botanical gardens where they can be seen, and for distributors in various countries. The site for North America is here.
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