Crocus January and February 2019

[Steve Garvie]

Thank you for your kind words Kris.
You only see images of my successes and not the many failures. 

Previously I grew Crocus in shallow clay pots in 40% grit/30% loam/30% composted bark. I lost a lot of plants in the past due to rot. The climate here is cool, damp and I am heavy-handed with watering. As a result I have had a lot of problems with Botrytis -usually starting in the spent flowers. Most of my winter-growing bulbous plants are in a partitioned well-ventilated 20ft x 8ft (6.1x2.5m) greenhouse where they grow in plunged clay pots. The plunge beds have thermostatically-controlled heating cables which activate below 4°C. The greenhouse also has a number of small fans which switch on and off many times -both day and night.

Despite all of the above the high humidity in the air and low winter light levels remained a real problem -especially when the weather was mild. So more recently I decided to turn it all on its head.
I now use long tom pots with a very sharply-drained inorganic potting mix for all of my crocus (and frits and iris......). I lined the greenhouse with insulating bubble plastic, closed the vents and have installed a dehumidifier set to keep the air humidity below 65%. I have also installed various led lights. It is early days yet but the drier air seems to be making a real difference as is the extra light during the short winter days.   

The downside is a significant increase in our electricity bills and a garden that looks like a parking lot for alien spacecraft!

Crocus hartmannianus in flower here. I have two different clones, the one purchased from Janis having broader petals. When back-lit the markings on the reverse of the tepals show through.

[brianw]

Do you recycle the water from the dehumidifier? Few off us can do that ;-) I have used only rain water for many years and although I cover all my collection tanks I wonder if I might have healthier plants using chlorinated water. If only I was not in a chalky area.

Can you clarify "inorganic" potting mix for me please? As a chemist I find the use of carbon compound free growing mediums interesting. Growing house plant bulbs in glass beads was popular many years ago I recall.

[Steve Garvie]

Thanks for your questions Brian.
Yes I have been recycling the water as it is useful for watering certain types of orchid (North American bog orchids, certain pleiones, etc). However the dehumidifier needs emptied almost daily as it is pulling over 3 litres per day from the greenhouse atmosphere and so I am tempted to use a continuous drainage pipe.

As regards my “inorganic” potting mix I mean that there is no humus content in my mixes (so no loam, peat, composted bark or leafmould). I use a mixture of perlite, 3-8mm grade pumice, coarse sand, granite grit, zeolite and often limestone chippings with powdered dolomitic lime. If I was being pedantic I would have to admit that the mixes are not totally carbon-free as I do add some powdered bonemeal to the mix whilst there are clearly carbonates in the limestone. I sometimes also add a little fine grade biochar depending upon the bulbs I’m growing.

I’m no soil scientist and appreciate that this is an over-simplification but amongst other things organic compounds in the soil bind macronutrients and encourage the development of beneficial microbial populations which can free-up micro-nutrients. Organic material also holds water in the soil.
However, in a pot containing a summer-dormant bulb (corm/tuber/rhizome) the retention of water is undesireable whilst organic material is more likely to encourage saprophytic fungi/oomycetes (many of which are facultative plant pathogens) than beneficial bugs. Adding small amounts of biochar and Clinoptilolite (a type of zeolite) to inorganic soil mixes will, by adsorption and cation exchange respectively, hold any added fertilisers and prevent nutrient leaching. I am now using chempak micronutrients fertiliser with my first autumnal watering and once again in the Spring, otherwise I feed with dilute tomato feed most waterings. This is all an evolving process and I will make further changes depending on results. However I am now no longer killing Onco and Juno iris whilst difficult semi-desert crocus such as moabiticus seem to be doing quite well.

As an aside, it might be worth adding a small amount of hydrogen peroxide to your water butts periodically to keep the water “sweet”. Five litre containers of 3% peroxide (food grade) are available from many catering suppliers for under £8.

[krisderaeymaeker]

 Thank you very much Steve for the clear and useful information !The winters here in Flanders are usually too humid and also too soft with a lot of lack of light.So a recognizable story .....So I always keep looking for the best way. 

[Janis Ruksans]

Oh happy people. Here started real winter. A night before temperature dropped down to minus 24 C at my locality. Wonderful view outside - see attached pictures - flowers designed by frost and sun only.
Inside greenhouse - you can see my bulb house for potted plants on 2nd picture - temperature during night dropped to minus 13 C only. The "warm" was kept in due snow cover on roof. All beds are covered now with glass-wool and below cover at top of pots (below crocus leaves) temperature still is around +1 C, but at bottom of pots +2 C, so I'm still not worried. All the day temperature stayed at around minus 14 C, but in late evening and during last night was some "warming" and temperature didn't fell below minus 7 C. You can see covered crocus beds in my earlier entries, so I not repeat them here.
The 3rd picture shows outside fields. Snow level is good - more than 20 cm and only tops of sticks separating stocks and hare footprints are visible.

[colin e]

Steve I do not know if this is relevant to your dehumidifier, but something you may want to bear in mind is that some have a copper element for the water vapour to condense on (or used to). If this is the case, the very soft water can take on some of the copper though this is probably not enough (?) to affect plants depending on how sensitive they are. The reason I say this is that I have killed fish because of this (I did not know about the copper element when this happened) and it took some time to figure out were the copper came from!  Just thought you might like to know.

Colin

[Steve Garvie]

Many thanks for this advice Colin. As you say copper is very toxic to aquatic life but paradoxically is also an effective treatment for Oomycetes (water-bourne moulds) such as Phytophthora, Pythium and Fusarium which all cause serious root rots. I still remember old aquarists using copper pennies to treat Ich.   

Conventional condensing dehumidifiers are of almost no use in a cool greenhouse as the coils freeze up and the dehumidifier becomes very inefficient. I use a dessicant dehumidifier which draws the cool damp air over a rotating zeolite disk. Water is absorbed by the zeolite which is then heated to discharge the water and replenish the zeolite -the water that is collected is very pure with little cation leakage from the zeolite (though it is probably best to discard this water for the first few weeks of operation). The air that is discharged from the dehumidifier is warmer. These types of dehumidifier are especially cost-effective in greenhouses where there is some additional gentle heating as they raise air temperature by a few degrees whilst it also requires less energy to heat dry air to a given temperature than it does moist air.

[Yann]

Spring has arrived 

Crocus sieberi subsp. sublimis
Crocus biflorus subsp. alexandri
Crocus corsicus, much taller than in the wild, the lack of sun...
Crocus thirkeanus

[Gabriela]

Thanks to all posting all these cheerful Crocus flowers!
I cannot even choose a favourite

[Yann]

that's why we grow so many ones this one, oh no this one, oh no this one 

[Yann]

a few more today

Crocus uschakensis
Crocus versicolor

[Steve Garvie]

Crocus corsicus


Crocus isauricus


Crocus korolkovii Tadjikistan


Crocus hartmannianus


Crocus chrysanthus

[Janis Ruksans]

Regardless of minus 13 C outside I'm not out of crocuses. I'm shortening time which will be needed in summer. I'm always at collecting and harvesting collecting corm tunics, too. Now is time to open small packets, to check them and to make pictures + description on matrix, used for each sample. Now I'm working on last seasons Iranian gatherings. Between corm shells in one packet I found excellent seed pod, collected in Iran, so it was possible to add picture of seed pod and seeds and to describe them in my notes. Will it be new species or will be identified as Crocus iranicus, without leaves and flowers I can't judge now. This stock was observed on steep slope growing in dense grass near very large Anemone field of various colours. Seeds were cleaned and sawn. Fortunately I had several pots with soil prepared for some unexpected or late coming seeds. Pots were frozen but I brought them in cool veranda, where they defrosted, saw the seeds and several times put on top large snowball - to water seeds with snow-melt water, as it happens in nature. Some are telling that this stimulates germination. I don't know, but it is easy way when you have outside 35 cm of snow. View to one part of garden this morning on the last picture.

[Steve Garvie]

Only -5°C here this morning. Despite the cold outside crocuses under glass are opening their flowers when the sun shines.

Crocus nubigena -from seed collected by Marcus Harvey.


Crocus abantensis


Crocus x gotoburgensis


Crocus taseliensis


Crocus taurii

[Tony Willis]

Steve C. x gotoburgensis seems to be building into a nice clump.

Crocus pelistericus and Crocus scardicus