baskets are better than clay pots?
 

Hi everybody, my name is Marcello, from Italy, and I'm a Nepenthes grower. My question is related to Nepenthes, but I already know that in our Nepenthes forum I wouldn't receive an answer as good as the one I can receive in an orchid forum, as the nature of my problem is closer to something you orchid guys deal with daily :)

I started growing many plants in one big pot, after having tried for many years to grow many plants in many small pots. My main problem was with the roots not having enough space to grow, and with me not having enough room to host tens of larger pots :)

The thing is that now I have a different problem, which is the amount of oxygen going through these 2 new huge pots that host my plants. At first I tried with plastic pots, but of course when a compost of peat and perlite goes into a plastic pot that is 50 cm large and 50 cm deep, what happens is that under the first 15 cm of compost, oxygenation is very poor, and plants stop growing. I changed and I bought a clay pot of that same size. The plants improved, but they are still slow and unhappy. At the same time, with another group of plants, I built a square basket (50 x 50 x 50 cm) using an iron net, so that of course the air is going freely all around the surface of the basket, enterind the compost from all sides and - I guess - with a bigger air exchange compared to the clay pot.

In fact, here comes the question: in your experience with orchids, did you ever notice if - in the case of such large pots - plants grow better in large baskets than in large clay pots, even if clay is famous for "breathing"?

I think the plants in the basket are doing better, but I have to deal with the fact that they are a different species and that here it's winter and so both groups naturally slow down, so it's not easy to tell the difference and to understand where the plants are slow for the lack of oxygen and where they are slow for the cold weather.
Thanks!!!!
Marcello

Hi Marcello and welcome to Orchid Board.

Personally I try and avoid really large pots, for just the reason that the ogygenation is often poor in a larger mass of medium.

However in the smaller scale I have found that 'net pots' give better air flow. That's only on a smaller scale than you are talking about though.

Hopefully some others will come along with their experience soon because it's an interesting question.

Another difference is that most of us have our orchids in a course bark mix as they get large. This promotes air exchange. Maybe you could mix in some larger medium with you peat and perlite to loosen the mix for the roots? I am kind of a nooB so it is just food for thought.

Welcome to the Orchid Board. Composite should be airy, I use clay pots with slits down the sides, foam peanuts in the bottom, bark chip and loose stone for a very airy media. Anytime your composite gets packed its going to cut the oxygen. Many times isn't that why roots grow right out of the pot. I hang all my claypots which helps the air flow too.... Orchids seem to grow well with no pots. Give me air!

I mix in chunks of styrofoam non melting type to create air pockets in the mix ..

For the size pot you're talking about, I'm not sure that the increased porosity of clay or net baskets would do a lot to prevent dead spots in the centre of the mix. You may want the 50cm diameter to give the roots more space to grow but do you need the 50cm depth? Have you considered a 50cm squat pot? Alternatively you could place an upturned 30cm pot in the centre of the 50cm standard pot to displace the stagnant mix at the centre of the pot - using an upturned net pot would allow for greater air exchange but unless you line the base of the pot with sphagnum or similar you'll find your peat : perlite falling through the netting.

Regarding your mix, personally I don't like using peat : perlite mixes for Neps. I have problems with peat mixes getting too heavy in medium and large sized pots. Nep growers in my area seem to favour sphagnum, usually mixed with coarse fillers like orchid bark to stop compaction as the mix ages. I've seen very healthy Neps in 30cm standard pots grown in this mix.

Eh, my problem is right with the depth of the pot, the width is just to host more plants. Many species and mines in particular (tuberous, with a deep vertical rootstock), send down a vertical root, and they stop growing as soon as this root meets an obstacle. Other species just send the roots out of the bottom holes, some others will rootbound without caring too much.

Anyway, the idea of the pot in the middle is nice, I might use that for the next basket. In these days I decided to just build another basket, as for some reason it seems to work better than clay. A few months will be needed to see if it actually works, and possibly summer months.

Yes, my Australian friends use sphagnum mixes, but that's because with your wonderful weather the plants are much more vigorous and they will appreciate wet composts, as they will dry in a matter of 1-3 days. If I pot my plants in sphagnum+bark, they will stay wet for a month :biggrin:
Highland species seem to favour sphagnum, here too. Don't forget that in their natural habitat these plants usually grow in plain sand (especially the species I grow), clay, less often in peaty soils, nearly never in plain live sphagnum. It's a good compost, but in the wild it will submerge young seedlings.