Monday, 29 April 2013

Beauty and the Brithys

There is always a price to pay for beauty...

If your name is Lily, or Aggie, or you go by the name of Amaryllis, or even Clivia, you'll know what I'm taking about. You may not have many enemies, but one of your worst foes is the beautiful-sounding Lily Borer...AKA Crinum borer, Brithys pancratii, or Amaryllis Caterpillar.

I've just finished a garden a few months ago, and having planted several types of rare bulbs, I was keen to see how they were doing. After visiting recently I was upset to find that this voracious little caterpillar was wreaking havoc on several different species of plants in the garden.
Eggs of Brithys pancratii
The moth lays its eggs, usually in clusters on the underside of the leaves.

This is why its sometimes called the Lily Borer
The larvae hatch, and bore into the soft fleshy leaves, often munching their way all the way down into the bulb.
The markings warn any potential predators that it is poisonous
I'm usually a firm believer in letting nature take its course, but sometimes something has to be done. Especially when the life of the plant is at stake.

The caterpillars usually recur regularly throughout the warmer months and less often in winter.  A pyrethroid-based insecticide sprayed onto the caterpillars usually does the trick in killing them - but it necessitates early spotting.

If I don't catch them early enough on plants like agapanthus, I will often take the drastic step of cutting back and destroying the leaves to prevent them from boring into the heart of the plant.

Monday, 8 April 2013

How To Transplant An Established Tree

I recently had a client email me asking for advice about how to move a relatively established tree. In moving any plant, there is always a risk that the plant won't survive. So of course, the best advice is to plan ahead, before you plant.
Flowers of the beautiful Halleria lucida tree

Do some research. Find out how big, how wide, how messy, and how deep the roots will grow when fully grown. The ideal is that you would never have to move a tree once it's planted...BUT that's not always possible - circumstances change, and it's not always possible to predict the future with any kind certainty.

Moving plants is always a matter of minimising risk - there are no foolproof ways of doing it. And every situation, species, and tree are different...sometimes, I think there is even an element of intuition involved.

But there are some things that you can do to reduce the risk of losing a plant that has been transplanted. Here is my reply to her, giving advice about how to move a particularly delicate tree:
  1. Dig the root ball out as deep as possible, and then slightly deeper still (basically a trench all around the tree - leaving as much soil around the roots as is possible that you can still physically move),
  2. Trim off about a third of the leaves.
  3. Leave the plant in place for about 2 weeks to let it get used to having less roots, but all the time giving the roots a little bit of extra water on the root ball as compensation.
  4. In about 2 weeks time, get your hole ready, measured and dug,
  5. Water the plant and the new location thoroughly.
  6. Trim off at least half the remaining leaves,
  7. Move the plant as quickly and carefully as possible keeping as much soil around the roots as possible.
  8. Try to position it in the same orientation that it was in its previous position.
  9. Firm the soil down around the roots and try to wash soil down into any gaps that may have inadvertently formed, (I'm not a big fan of using fertilizers when planting unless your soil is terrible, but even then I would rather use copious compost instead)
  10. And then leave it for a week or two...it doesn't have much in the way of roots so don't over water.
  11. Then wait - it may lose a few more leaves, or even a branch - losing leaves is not a big deal, but keep an eye on the stem. If you notice any rot, then you can trim off the dying branch/trunk and paint the cut section with a tree sealant.
  12. Then wait some more...sometimes I have given up hope on plants that look dead for a year or two, and then suddenly they come back...
Generally speaking, the smaller the tree the easier it will be to move. Also, if it was originally planted from a bag as opposed to self seeded, it will transplant easier. I've also found that trees transplant a lot easier in Autumn.

Weigh up the costs of losing a tree as opposed to keeping it in a place where it's not ideal - Is it really worth it?

Tuesday, 2 April 2013

Gardening On A Vertical

Plants love a good challenge... I admire the way they seem to survive thrive in the most death defying situations. You find plants growing in such diverse conditions - from Polar Bear hangouts right through to Desert furnaces. I've seen plants surviving on nothing but air, just clinging to rock faces. In the plethora of conditions that our amazing planet seems to dish out, plants seem to love to rise to any challenge.

Terramesh Wall Halfway Up
Cities pose their fair share of challenges to plants. Green Walls and Vertical Gardens have become 'the new thing' as people try to invite nature back into our inhospitable cities. They are an elegant solution to the stark walls and inert atmosphere of the places that we humans seem to flock to.

Several years ago, I built a green wall on a south-east facing, windswept balcony. Its been interesting to watch the evolutionary growth of the green wall, and I've used it as a proving ground for different plants to see which of them were best suited to this type of environment.
Some plants - particularly ferns seem to reproduce to the point of trying to suffocate everything else. Others, like a small aloe, and several different types of orchids have grown quietly and unassumingly before bursting into surprising flower. You can watch a video of how I built it here.

Green Terramesh being installed
An ongoing project (Romead Business Park) that we have been working on for quite some time, has posed several challenging situations which I hope to elaborate on in the future. One of the challenges, was the lack of space at the main entrance to the Park. We had some large banks that were held in place by a beautifully designed concrete curved wall. But the wall could only be so big before it would start compromising the design of the main entrance.

The final solution was to use a product called Terramesh from Maccaferri. This is woven wire mesh which is back filled and compacted with soil. Plants are then planted into the face, which in time forms a dense groundcover, and should prevent any long term erosion.

Just after planting
We planted up the wall, using a succulent called Crassula multicava. Its a plant with a happy disposition - content to grow on a South facing wall (no sun), and it seeds itself quite readily, and will even survive dry periods and still look very good. It has a pretty pink flower all through the year.
Before
After
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