Advice needed: Soil and fertilizer for growing in pots

[Edgar Wills]

Hey everyone,

So I’m a new forumer who has just started a snowdrop collection. Due to moving often and currently only having a balcony, I’m limited to growing the snowdrops in pots. Although it seems preferable to grow the snowdrops in the ground, there seem to be plenty of galantophiles who grow them in pots, and I was hoping to get some advice from those that do.

I’ve been trying to find the optimal soil ingredients for snowdrops. As far as I can tell it needs to be a peat-free, nutrient-rich soil. It should have good drainage by adding something like vermiculite or perlite. The soil should be changed at least every 2 years.

One recommendation I found in the book Snowdrops by Naomi Slade:
-2 parts super coarse perlite
-1 part good loam-based compost, such as John Innes No. 2 (I cannot really find this specific compost in the Netherlands, so I guess I’d have go for some peat-free compost)
- 1 part multipurpose compost
- add a third of the total made volume of leafmould and a pinch of bone meal

Not everyone seems to agree about peat-free though:
From http://www.judyssnowdrops.co.uk/cultivation/pots/pots.htm
The compost used for pots will be a personal choice, but aim for a well-drained, moisture-retentive mix. I use 50% peat based potting compost + 50% vermiculite.

What I also noticed is that for example Monksilver’s snowdrops had some coloured slow-release fertilizer in it.

What are your recommendations for the correct soil in pots? How often should you fertilize the plants and change soil?

p.s. Bonus pics. My three reginae-olgae bulbs I planted in september seem to be fine in normal peat based potting compost on top of a bottom layer of hydrograins. First pic in october, second pic now.
And because I can - third pic of a collage of snowdrops of Cathy Portiers nursery garden in Brugge/Belgium that my girlfriend made. It becomes clear with this image who's the better photographer between us.

[Alan_b]

I use a mixture of 7 parts John Innes No.3 to 3 parts sand.  John Innes composts are prepared to a specific formula; details are given here: https://www.rhs.org.uk/advice/profile?PID=952.  I live in the driest part of the UK and might use more drainage if I were somewhere wetter.  The pots are kept in shade or semi-shade during summer and covered with a fine mesh net to guard against insects. 

I usually add some Trichoderma harzianum (although it has a limited shelf life and I frequently end up keeping it too long before use).  I use 3 litre pots to increase the thermal mass so it would take longer for the contents to freeze in severe weather.

I feed sporadically with a tomato fertiliser.  I have some pots where I have not changed the soil for 5 years.

I doubt that what I do represents the optimum but it works tolerably well.     

[Edgar Wills]

I use a mixture of 7 parts John Innes No.3 to 3 parts sand.  John Innes composts are prepared to a specific formula; details are given here: https://www.rhs.org.uk/advice/profile?PID=952.  I live in the driest part of the UK and might use more drainage if I were somewhere wetter.  The pots are kept in shade or semi-shade during summer and covered with a fine mesh net to guard against insects. 

I usually add some Trichoderma harzianum (although it has a limited shelf life and I frequently end up keeping it too long before use).  I use 3 litre pots to increase the thermal mass so it would take longer for the contents to freeze in severe weather.

I feed sporadically with a tomato fertiliser.  I have some pots where I have not changed the soil for 5 years.

I doubt that what I do represents the optimum but it works tolerably well.     

Hi Alan,
Thanks for your reply, you seem to be the only one willing to reveal his secrets of growing snowdrops in pots so far. 

I especially like the idea of cover with a mesh guard against insects, it should prove useful against those narcissus flies. When reading online they seem to start being active around may, so I guess you should cover up by then.

Did you notice a beneficial effect of the fungus? It is a new concept to me, but I think mycorrhiza might well have a positive effect.

I'm using some smaller pots than 3 liters, but the advantage of pots is that I can move them inside easily in case of frost.

Best regards

[David Lowndes]

Hi Edgar
I follow similar practice to Alan but with the addition of a little horticultural grit. I add the same mixture to any outside planting area too. The point about the compost is that it is important to use a loam-based one rather than one without any loam.  Alan is right to mention the size of the pots.  They need to be large enough to resist freezing.  Freezing is pretty damaging to many bulbs.  During the recent very low temperatures here I sunk my pots in raised beds inside my polytunnel and they were fine. I think it would have been ok to have sunk them in the ground outside and covered with fleece too. The snowdrops in smaller pots were kept inside a frost free greenhouse with olives and lemons while it was very cold!
Hope this helps.

[ArdfearnAli]

Hello there,
                I noticed John Innes compost being mentioned an if you are buying John Innes compost beware!! There are a lot of different commercial companies that sell so called John Innes compost and so far every one I have come across is not up to standard. I have even seen peat free John Innes? Even the well known compost manufacturers brands seem very poor. My polite description of them is mud in a bag. They have little or no fibre and tend to sit very heavy and wet. From what I understand John Innes compost was originally made from sterilised loam sourced from stacking turf and then it was either heat treated or steam sterilised. This retained the structure and fibre of the loam. It was then mixed with peat,sand and base fertiliser etc. It was also designed for clay pots which are porous so let air through to the roots. If growing in plastic pots you have to increase the drainage/air porosity with grit or very sharp sand. Perhaps someone on here could recommend one that is up to the original standard. I must add I am not against John Innes compost at all but I have had a lot of my customers having problems with growing plants in poor substandard versions of John Innes.

Alasdair

[Shauney]

I  grow most of my snowdrops in 1 litre square pots and I use 1/3 of a clay based garden soil 1/3 of a peat based potting compost and 1/3 of leaf mould. I've had no problems growing in this mix.

Shaun.

[Edgar Wills]

Thanks for the tips all!

I think I’ll try something like this from now on, as it seems a bit too difficult to make / obtain this John Innes compost here in the Netherlands:
1/2 loam-based compost
1/2 vermiculite + some horticultural grit for extra drainage
some leaf mould mixed in, and see if this Trichoderma harzianum is effective.

I think I’ll add some slow release tomato fertilizer when the plants start to grow and at the end of the growth season. During the winter I’ll take care to protect the pots against frost, take them to a warmer location if necessary. End of april I’ll try to cover with mesh guard against insects.. Hope it'll work to keep the 'drops happy.

[Edgar Wills]

hey guys, small update.

Noticed this post on Yanik Neff's snowdrop site:
https://www.facebook.com/swiss.drops.ch/photos/a.1497255817030285.1073741828.1496060313816502/1531816890240844/?type=3&theater

It mentions a more complicated soil mixture.

Hagen Engelmann also mentioned a more complicated mixture for autumn snowdrops here:
http://www.srgc.net/forum/index.php?topic=7933.15
"Mike, there is realy no treasure:
30% compost, not too humous
30% grit
15% shreddered leaves of beech
10% perlite/vermiculite
10% silt/loam/clay
2,5% eggshell/lime
2,5% best wishes"

Would these be better than what I previously mentioned? Is there a difference between the needs of 'normal' and autumn snowdrops?

[Blonde Ingrid]

Is there a difference between the needs of 'normal' and autumn snowdrops?

Just finished knocking out and re-potting my Autumn drops. Bumper year with many additional bulbs! There is no trial data that I have seen so I looked at grower's mixtures that have given great success and altered mine to suit local conditions (here very hot and dry). There are plenty of awful mixes out there, as you will see (the worst I have seen had shredded newspaper instead of grit!!!!!!

I use a light mixture for both the Autumn drops and main non yellow drops i.e
40% JI3
20% Composted bark
15% Cornish or fine grit
15% Horticultural grit
10% Perlite

During the growing season I feed with a light liquid feed each time I water. This compensates for the light mix. It seems to do very well for me.

[Edgar Wills]

thanks for the advice Blonde Ingrid.

It seems that you and Hagen Engelmann largely agree, and in absence of trial data we should look to expert opinion.

I'll try something closer to the mixture that you mentioned. In comparison to my previous mixture suggestion less perlite/vermiculite  and more grit seems wise.