Monday, September 13, 2010

Germ-free repotting

I was reading in a history book recently about the dreadful standards of hygiene in hospitals back in the 18th and 19th centuries, and it occurred to me that sometimes the standards of hygiene in the plant hospital out in my own backyard were little better. So, while I knew that I should sterilise secateurs when moving from one plant to the other during a pruning frenzy, I wasn't all that meticulous about it. Just think about it. A doctor comes in and says he's going to operate on you, using the same, uncleaned, instruments he used to operate on the previous patient. No way! The same goes for the hospital beds – you wouldn't want to get into the same, unmade hospital bed previously occupied by someone else. Yuk!

So, repotting my recent purchases was the perfect opportunity to put my new-found zeal for cleanliness into action, so here's how the germ-free repotting at Garden Amateur's reformed 21st-century plant hospital went.

Told you the standards of hygiene have improved. Bucket of warm water with a couple of glugs of disinfectant Pine-O-Cleen added. Scourer pad awaiting duty.

Six previously used pots to clean. The first step is to wash out all the old soil and scrub it down. (This is my birdbath cleaning brush, worn down into a birdbath shape over many years.) Once each pot was mostly clean, it then got the scourer-and-disinfectant treatment to get it up to hospital standards.

And here they are now, clean, germ-free and ready to take on their new occupants, hopefully for several years at least. All this cleaning is important. Just like people, plants get sick, suffer diseases, viruses and other ailments. The pathogens can lurk in the leftover potting mix and will potentially attack any new plants added to the pot. So, a bit of cleanliness lowers the overall mortality rate, just as it did once reforms to hospitals were made.

I love my plastic trugs, they get used for so many jobs in the garden. I have three in my shed, and two of them were indispensible this afternoon. This green trug was my repotting area for the orchid, catching all the old orchid potting mix, so I could work without making a major mess just outside the back door.

Unpotting plants is one of the most revealing things you can do. This is not the first time I've unpotted an orchid and found styrofoam chunks instead of orchid mix. I just don't like the look or the idea of styrofoam, even if I suspect it works quite well to improve soil drainage.

This is the dendrobium orchid after repotting. I use a specialised orchid potting mix for all my orchids. It looks and feels like composted chunks of bark, and it's very coarse indeed. In nature, orchids don't grow in soil, so ordinary potting mix isn't right for them. Orchid 'roots' cling onto branches or trees or rocks in nature, and so orchid potting mix is just a coarse, very free-draining medium for the roots to cling onto.

For the bromeliads, I mix up ordinary potting mix with orchid potting mix in a 50:50 ratio. Again, I use a trug to make this job easy, just adding three scoops of orchid mix to three scoops of potting mix, and mixing it all up well. Like orchids, bromeliads don't grow in soil in nature – they also cling onto tree branches and rocks, and the main thing they need is very free drainage in their growing medium.

Succulents do grow in soil in nature, but usually it's sandy, crappy quality soil, and so for them I use a specialised cacti and succulent mix. However, you could use a home-made 50:50 blend of ordinary potting mix and clean, coarse sand. The specialised potting mix is very coarse and sandy, providing the excellent drainage that succulents like. I only use the specialised stuff due to a certain laziness, I guess. I really should mix up my own stuff and buy less 'product'.

It only took about an hour from beginning (scrubbing) to end (taking this photo), but I am always very pleased to see plants in nice terracotta or glazed terracotta pots. I'm not sure whether it is OK to repot native orchids when in bloom, but I repotted the ones I bought in bloom last year, and that didn't affect them then and they are blooming nicely now, so I just figured they must be so tough even I cannot kill them.

Instead of just doing a blog about repotting, I thought I'd introduce the 'hospital cleanliness' idea as well, because reading that book about the appalling hospital standards a couple of hundred years ago did make me think about my standards. That's because the only things I am ever going to 'operate' on are plants, and as they are living things just like me, subject to diseases, they really do deserve at least a basic level of good hygiene, and in return more of them might thrive here in my garden.


lotusleaf said...

I learnt a lot from your post. Thanks.

Lanie said...

Good reminder Jamie - thanks...the cleanliness standards in garden are dreadful. Will put 'Pine O clean' on the shopping list and follow your lead. Cheers.

Melinda said...

Thank you for the information Jamie. I will also endeavour to practise higher cleanliness with my pots.
Before I asked you about potting mixes for broms, I had asked someone at Flower Power and she recommended pot-and-peat. I bought a bag and I'm now wondering if it's close enough to the mix you make up?

Jamie said...

Melinda, you could give Pot n Peat a try, but it's what I'd call ordinary potting mix. Bromeliads are pretty tough, though, so if you really don't feel like spending more money on some orchid potting mix to mix into the Pot n Peat you could probably get away with the Pot n Peat.

However, as the Pot n Peat breaks down and slumps into the pot (ie, the soil level gets further away from the pot rim) the soil drainage might become poorer as the potting mix condenses, so you might have to repot them earlier than expected.

Melinda said...

I think I'll invest in the orchid potting mix, rather get it right the first time round. Plus it makes for a good excuse to buy some native orchids to use up the rest of the bag!
Thanks so much for the advice, I'm sure Hilda & Mango (mine also came with cute variety names) will be most pleased.

Jess said...

Thanks for the informative post! I'm just wondering whether you rinse the pots well after you've scrubbed them with the disinfectant or do you just let it dry out?

Jamie said...

Just let them dry out in the sun, Jess.

Candy "Sweetstuff" said...

Very nice post. I should clean out my pots better before I reuse them!

Paul said...

I have a roll of individual alcohol swabs which I use for my secateurs and hedge clippers, but I had never considered the pots themselves. I think I need to re-pot one of my roses into a sterile pot. No amount of spray or pruning seems to be able to rid it of black spot.

Anonymous said...

Great post; admittedly I've never even cleaned my secateurs between plants, only cleaning them at the end of the gardening session to be put away. :o I wondered about the disinfectant reside in the pots too; I guess by now you would've seen some indication of this in the plants if it were a problem?

And timely too; your post has reminded me that there's an orchid show on in walking distance from home tomorrow.

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