Frost free greenhouse review

I have just been going through my plants that have been overwintering in my frost free greenhouse. I thought I would record my findings as I am interested in knowing which tender plants will survive just frost free, as opposed to needing extra heat.

Evergreen - green all winter and growing new leaves now.
Aristea major
Campsis radicans
Cantua buxifolia
Echium russicum - actually hardy to -20C but often dies from the damp.
Geranium maderense
Isoplexis canariensis
Isoplexis sceptrum
Justicia carnea
Pelagonium rubicinitune x cordigolium
Pelagonium unique 'Mystery'
Salvia 'Amistad'
Strelitzia - the leaves are rolled - I don't know why

Bulbs/tubers - sprouting
Agapanthus
Arisaema speciosum
Arisaema tortuosum
Asphodelius
Colocasia esculentos (Eddoe) lost all its top growth but the tuber looks sound.
I was pleased to see A. speciosum sprouting, as last autum I lost one tuber to rot and had to cut the bottoms off the other two, when I lifted them from the border. I had to excavate A. tortuosum as nothing was showing - but it was just starting to bud.

Signs of life
Alygoyne
Clerodendron ugandense
Echium candicans
Lobelia laxiflora
Tibouchina urganvillea
Alygoyne and Clerodendron have tiny buds - almost too small to see. L. laxiflora is growing strongly. E. candicans is curious as it has lost its main growing poin, but unlike other Echiums, it has masses of tiny buds coming from the main stem. Generally Echiums die if they lose their growing point - but candicans is an exception.

Plants - no signs
Asclepias
Canna
Duranta
Echium pininana - lost its growing point - probably dead
Iochroma - I know these are OK - they are late starters
Plumbago
Streptosolen
Streptoselen may well be dead, but the others all have a bit of green on the stems, so I am hopeful. Even the E. pininana has a bit of green - but it doesn't usually recover from loosing its growing point, so I am not hopeful. Virtually all Echiums will take frost free conditions, but its the damp that makes the crown rot. Next winter I am going to try spraying the crowns once or twice with a copper compound.

Bulbs/tubers - no signs
Amorphophallus rivierii - totally rotted away. Probably wet not cold.
Bessera elegans - haven't investigated
Ismene festalis - I bought 3 bulbs 2 years ago - never flowered, but I now have 6 much smaller bulbs. I suspect not enough heat in the summer.
Sprekelia - bulb looks happy and has an offset - never flowered last summer.

Overall I am very pleased to see that nearly everything came through.

 

All the Coleus I had in the conservatory have gone - too optimistic (benefit of hindsight!)

I have some coloured labels (eBay, cheap as chips) and I put them into pots (or near plants, in the Autumn, prior to lifting) that colour-code for:

Leave bone dry until Spring
Give very little water
Must not be left in Frost Free conservatory, needs more heat

so that when they come in they get grouped with other plants, with similar coloured labels, that thus need similar treatment. Otherwise when watering things, in mid-Winter, the watering can accidentally strays onto "must stay dry" plants :(

 

I would be interested to hear from others what will survive frost free and what won't. And what sort of temperatures other plants need.

For instance, I have more plants in my summerhouse. Fuchsia arboresens and boliveana are OK frost free, but triphyllas like "Thalia" are not. For me those need to be in the house.

 

Surprised you think "F. thalia" needs to go in the house Peter, I overwinter it almost dry, I think you do need a woody plant for it to work though.
I overwinter, Erythrina, Bougainvillea, A couple of Brugs, CIDP,Fucarea,Yucca elephantipies,Hedychium gardnerianum, Brachychiton, Scinus molle, Butia capitata all in a dim draughty garage.
I'm sure the temperature dropped below freezing on quite a few nights last winter, but all were dry or dryish, and in most cases leafless.
I kept plumbago,beaucarnea, passiflora,a varieagated brug, epiphyllums and desert cacti,Aloe vera, Gloriosa tubers and a lot of other stuff, frost free.
Including a Hymenosporum, which is just coming into flower.

I moved into the conservatory where it is much warmer, Plumeria, Adenium, Phalaenopsis, Passiflora alata.

 

Frost free in the shed;
Iochroma australis (all in bud) and I.cyanea (not hopeful).
F.thalia - 50/50 if I'm honest.
Salvia discolor - a goner
Pandorea jasminoids - stayed evergreen and growing like boogery now that it's back in the g/house.
All my Arisaema, Dracunculus, Eucomis, Bessera etc, which are all budding. All my Gloriosa rotted though.
Salvia Wendys Wish - 50/50
Cantua - not looking good.
Albizia julbrissian seedling (about half a metre) which is leafing up nicely.
A young Abutilon x hybridum which is also leafing up well. The one in the garden was fine up to the last cold spell.

Cold in the greenhouse;
Lobelia tupa and laxiflora (laxiflora looks iffy)
All my "precious" Tricyrtis, which are good.
Iochroma - not good
Passiflora "Amethyst" - no sign of life yet.
Salvia Black and Blue - rampant!
Fuchsia procumbens - no sign of life, but should be ok.
Another Cantua - deffo a goner!
Various Salvia seedlings in covered seed trays, all looking good.
An Echevaria which seems fine.

In my bedroom (as it's the largest room and gets the best sun in winter) is my P.alata!

 

Bought one last Autumn, it was in a 9cm pot (so a "tiddler"). Didn't know any better so left it in the frost free conservatory ... its still alive Minimum temperature was probably around 3C - 5C (I can look up exactly what it fell to if you need me to?)

My Bougainvillea doesn't look good, nor the Stephanotis. Cheese plant and Umbrella plants are fine though.

My Plumeria, in frost-free conservatory, is now dead.

 

Scrach my Bougainvillea, it survived ok last year in the garage, but on closer inspection it appears dead, possibly I kept it slightly too dry.
I find its a very fine line with most plants, dry enough to not rot but at the same time not so dry the plant dehydrates so badly it dies.

I also think it varies from plant to plant, so is likely to always be a bit of a gamble.

 

For my sins I have just received some Plumeria seeds. Always said that I wouldn't fall into that trap, but I'm weak!

Possibly where I went wrong with my Cantua. Gutted about that one.

 

I do agree - I think dryness of plants plays quite a element in hardiness. In part I think it depends on how wet they were before being moved under cover. It can be very wet in late autumn and pots can be almost waterlogged. I have noticed how much of this water comes out over the winter as condensation.

Pete made a very good point some time ago about leaving some foliage on Cannas to draw up the water from the wet pots. I suspect that its relavent to other plants too.

Incidentally,when I overwinter plants in my house I find using a moisture meter very helpful. I have side by side - Echiums, that need lots of water, and Hibiscus that lost all its foliage and now has just has a few shoots showing and needs very little water.

 

I'm definitely going to concentrate on this next Winter. I had good intentions last Winter, but events overtook me and I wound up just stuffing everything in then, when watering, some things that should be dry accidentally get watered.

I did put my Coloured Labels on plants whilst still in the ground - to indicate what "zone" of the Winter Quarters they were destined for ... but despite good intentions it went Pear-shaped somewhere between Border and Boarding :(

This year it will be better ...