Substrate and re-potting

[yorkshireal]

Hi,

Apologies if this is a previously-asked question, but I have searched the forum and not found what I was looking for. It may be that there is no perfect answer!

There are two strands to my question, one is about temporarily uprooting plants, and the other about best substrate to use.

I have a collection of succulents, a mix of caudiciforms including Adeniums, Pachypodiums, Sarcocaulons, Cyphostemma and Cerraria, but also quite a few small Aloes, Gasteria, Echeveria, Lithops, Adromischus etc. Many of these are planted into a large 'desert' bed in my conservatory. Traditionally I have used a mix of equal parts of John Innes no 2, horticultural grit and sharp sand. By and large that seems to work well, and most of the plants do fine, but I think the caudiciforms perhaps less well (although that could be down to temperature extremes in summer (too hot) and winter (too cool - down to about 8 deg). What I have noticed, when repotting plants, is that this mix can become very 'congealed' once soaked, and doesn't seem aerated and well-drained. I'm aware that a lot of people use a mix of pumice with coco-coir, and have started to use this for some of my plants (but that more feeding would then be required). I've also heard people swear by a 40:60 mix of John Innes no 2 and 'flint chick grit'.

I am now having the conservatory re-roofed (the glass roof is too hot to tolerate - temps can hit 60deg C!) and am replacing it with an orangery style roof - which should allow better temperature regulation both in summer (cooler) and winter (hotter), hopefully without losing an unacceptable amount of light, as the plant 'bed' is adjacent to the window anyway.

As I am having to move most of the plants, many of which are rooted directly into the bed rather than in individual pots, I wanted to ask:

1. Would it be unwise in growing season to simply leave the plants in a sheltered place bare-rooted for up to 2 weeks while the work is being done? Should I repot immediately and keep on windowsills in the house, if I can find room?

2. Given that I will be repotting them either directly into a large bed, or in pots within that bed, any guidance about best mixture/substrate to use?

Many thanks

Alan

[Chris L]

If they are only in the way because of the risk of falling glass (rather than in the way of the builders/construction people) would it not be possible to cover them with something? Large cardboard boxes or some kind of wooden frame.

Pumice is a good addition to (probably nearly) any compost mix.

[Tina]

pumice is good but seems a bit variable & expensive what we can buy, I have been using cat litter for years and this is a standard size ( two sizes are available) & easy to buy, I have never used sand.

If its only for two weeks of being uprooted most of the plants will be fine with that, keep out of the sun .

Everyones mix is different, mine for caudiciforms would be 2/3 cat litter, 1/3 john innes at the bottom quarter of the pot & then pumice if I have it. My thinking is they root happily in the pumice once the roots get long enough they will get some nutrients from the soil mix but as there is a lot of cat litter there is still good drainage & no soggy roots.
I don't feed that often maybe I should.

[peter831shaw]

IMHO, one of the most important steps in using kitty litter or pumice or perlite or whatever you use for aeration is to sift it properly. I have found pumice to be the worst offender as its easily pulverized during transport. Sifted pumice is very expensive.

I use a product called Turface (used on baseball infields to absorb water!) which is ~ the same as kitty litter and sift it with a 2mm screen. I loose about 1/3 of the product, and the same for perlite. (Turface contains 3-5% silica sand which is really small and can get in your lungs so be careful sifting it. I use an old set of soil sieves with a lid and pan. Sifting perlite is worse so be careful as well.)

Can't say I like the idea of organic material at the bottom of the pot. Holds a lot of water that should be allowed to drain or it will be pulled back up. This OM also should be screened. The Coco I use also has a lot of dust which I like to remove.

I do like to add a little bit of worm compost as a nutrient source.

Good luck with your greenhouse project, sounds exciting and would love to see a before and after pictures. Orangeries are beautiful.

[MikeT]

I wonder whether the sand is causing the problem. It can fill the small spaces and reduce the amount of air. I'd either replace it with cat litter (the baked clay granules) or simply omit and use 50-50 JI and grit.

[fero]

Above on substrates sounds good . If I was you I'd pot the plants.. dont leave them bare root.
The plants you have mentioned are heat lovers. Indoors isn't usually light or hot enough for them at this time of year, also out side without protection will be too cold or wet or both.
Maybe you could create a closh or small pollytunnel.
Also projects like this always take longer than expected.
Hope it all goes well.

[Tina]

I have never had to sieve cat litter even the bottom of the bag isn't that dusty

[yorkshireal]

Many thanks for all the advice. I will certainly omit sand in the future, and will be more willing to use a coco/pumice mix for caudiciforms, but perhaps grit/JI for the remainder. Inside should be warm enough for a couple of weeks, and I'll put what I have room for in the greenhouse.
Many thanks to all
Alan

[Pattock]

coco/pumice mix for caudiciforms,

If you are going to use coir, I woud recommend that you use Canna Coco Professional+. It has been treated with calcium and magnesium nitrate. Untreated coir will soak up all the calcium and magnesium ions in your plant feed (and release potassium ions) until all the sites in the coir are full. This will starve your plants of calcium and magnesium.

Your choice which dodgy shop you get it from.

[Bonsai2]

pumice is good but seems a bit variable & expensive what we can buy, I have been using cat litter for years and this is a standard size ( two sizes are available) & easy to buy, I have never used sand.

If its only for two weeks of being uprooted most of the plants will be fine with that, keep out of the sun .

Everyones mix is different, mine for caudiciforms would be 2/3 cat litter, 1/3 john innes at the bottom quarter of the pot & then pumice if I have it. My thinking is they root happily in the pumice once the roots get long enough they will get some nutrients from the soil mix but as there is a lot of cat litter there is still good drainage & no soggy roots.
I don't feed that often maybe I should.

For the last 6 years, I have grown my Mesembs in 25% JI2 and 75% RHS grit. I am now finding that most JI ranges from poor to rubbish. I sieve it before repotting and find stones, twigs and even live roots. A few weeks ago I planted 7 species of Mesembs in 100% (3mm) Pumice. So far, I am happy with the results and will continue over the next 12 months. I did consider peat-free JI. A friend with around 1,200 cacti & succulents purchased Sylvgrow peat-free JI and was very disappointed. Although Pumice is expensive, it is also reusable.