Friday, 21 June 2013

No, Puyas are NOT carnivorous!

Sheep farmers needn't worry about a menacing plant at RHS Wisley attacking their sheep! First, read the original story here:

Puyas are terrestrial bromeliads native to fairly arid areas of South America, with most originating from the Andes. They are notorious in specialist gardening circles for their stiff and vicious backward facing spines that can easily ensnare an unsuspecting hand. Interestingly Puya raimondi holds the record for the tallest flower spike of any plant, a staggering 32ft (10m) tall!

But are they carnivorous? Despite disagreements from anyone who has lost their own blood to this genus, they are not. Carnivorous plants are specifically adapted to lure in their prey, usually with the promise of tasty nectar, but then trap the prey in sticky goo (e.g. Drosera), pitfall traps (e.g. Sarrecenia) or in a fast moving trap (e.g. Dionaea, the Venus' Fly Trap). There are a couple of disputed carnivorous bromeliads too, Catopsis and Brocchinia, but these are epiphytic 'tank' bromeliads and are very different from Puyas.

Stories about Puyas feasting on sheep are probably exaggerated- no doubt sheep occasionally get trapped in the huge rosettes of Puyas, and cuts to the face from the sharp spines are probably fairly commonplace (after all sheep aren't all that bright!) but there's nothing really to suggest that the Puyas are munching on fresh lamb!

I originally saw this story in the members magazine of the Eden Project in Cornwall, although it might have come second hand to them. As my friend showed me the article I was astonished to read these claims of carnivory being peddled by a so-called educational establishment. To find this dubious information being passed on by the RHS is doubly disappointing, but I suppose the promise of a rare and macabre plant will do no end of good to their visitor figures, but there's one thing puzzling me; Puya chilensis is a rare plant with vicious spines that seldom flowers outside the mild gardens of Cornwall, but when it does it produces a flower spike 10ft (3m) tall... why isn't that impressive on it's own?!

Wednesday, 19 June 2013

8 Urban Myths In Gardening

With so much information around in gardening it's no wonder things sometimes don't come out quite right. Here are eight urban myths in gardening

Agapanthus need to be pot-bound or they won't flower
Nope! Agapanthus flower very well in the garden, large clumps often bearing dozens of fabulous flower heads for weeks in the summer. The secret to success with Agapanthus is good life- good rich soil, enough water during the summer (although not too much during the winter) and plenty of sunshine. The myth that Agapanthus need to be pot-bound probably stemmed from a misunderstanding; Agapanthus flower better when they've made a clump- dividing your Agapanthus into small chunks won't help it flower. Plant your Agapanthus out in the right spot and then leave it!
Perfectly happy in the garden- Agapanthus inapertus 'Sky'

Nerines want to bake in hot, dry and poor soil
Nope! Not sure where this has come from; Nerines are happiest in good garden soil with good drainage (but not dust dry!) and with plenty of sunshine, here they will bulk up beautifully. The larger the bulb the better the flower display. This myth might have come from Holland, where bulbs are treated with hot water to stress them into flowering when the bulb is too small- this is all well and good for bulb merchants, but in the garden it is better to focus on building up the bulbs naturally for long term benefits.

You should water your plants every day until they're established
Hmmm, no.... Although this is rooted in common sense, it is generally reckoned to be better practice to water your new plants really well 2-3 times a week (normally twice a week, three times a week if it's very hot and dry) instead of a little and often. The sense behind this is that a few good soaks encourages the plant's roots to grow down and search for water, whereas watering a little and often encourages roots to stay near the surface (and makes the plant more susceptible to stress during dry weather).

Shallow pots drain better
NO! Garden books will tell you to put a nice layer of crocks (bits of broken pots/flat stones) at the bottom of the pot for drainage, but in fact current thinking is that a drainage layer at the base of the pots might do more harm than good. Compost is much like a sponge; if you saturate a sponge and then let it drain you will be left with a saturated layer at the base of the sponge, while the top has dried out. The same happens in a pot, but the drainage layer pushes that layer of saturated compost closer to the roots. If you want to get your compost to drain then pick tall/deep pots which keep the saturated layer of compost further away from your plant's roots. Often if you remove a nursery grown plant from it's pot you will find that the roots aren't quite as keen to fill the bottom centimetre or so of the pot, and it's because of this layer of saturated compost!

Add lots of grit to improve drainage on clay soils
Nope! This old wisdom can spell disaster- clay soils are made up of tiny particles and these mix with the grit, and in dry weather this layer stiffens into what could only be referred to as a natural concrete! Much better to add plenty of good organic matter to the soil, and this will improve soil structure.

Only native plants are good for insects
Insects need a ready supply of nectar from flowers, and the best way to provide plenty of food for native insects is to fill your garden with plants that will flower for as long a season as possible, and these are nearly always non-native species*. Try to make sure there's plenty in flower in spring and autumn for the early emerging insects and those late to hibernate.
Early flowering and good for bees, but this Mahonia 'Lionel Fortescue' is not native!

Plant snowdrops in the green
Nope. This old hunk of horticultural 'wisdom' is probably well enough known to have become 'ancient gardening lore'! It is, however, of dubious accuracy. Like all bulbs, snowdrops (Galanthus) are best divided when dormant, in this case in August. However it must be said that Galanthus bulbs have thin skins and can dry out fairly easily if not handled carefully; with this in mind you are probably best avoiding dry bulbs in bags from the garden centre! Lifting bulbs 'in the green' (when in full growth) is more convenient to commercial growers who like to lift and bundle Galanthus from the open ground, but this does cause the bulbs a degree of shock from the disturbance. Gardeners really should try to lift and divide their bulbs in August, making sure that bulbs are planted again very quickly, and the bulbs will grow away healthily in spring.
Galanthus 'Straffan'- please divide when dormant!

Alstroemerias must be grown in pots
Hmmm, well possibly. Alpine species and tender varieties need to be in pots out of necessity, but the garden hybrids really are much better in the ground! Alstroemerias like good deep garden soil with good drainage (see the bit about drainage in pots above). In pots plants can easily get overcrowded and pot-bound, as well as needing a lot more feeding and watering. Also plants in pots are more susceptible to damage by frost being able to get into the too area from all sides. I would suggest assuming that any Alstroemeria grown in a pot is tender. In the garden, however, Alstroemerias have ample soil to grow in, are less susceptible to drying out and are better protected from frost. For best success it is wise to give your Alstroemerias a thick layer of a dry mulch (bark chips would be ideal) for the first couple of winters while your plant gets established.
Alstroemeria 'Inca Exotica'
*Conserve native plants for their own sake!