[bobbyt]

Got my very first greenhouse last year during lockdown in April, so no experience, but have only germinated some broad beans and runner bean seeds in there during last summer. I live in S.Wales.
This year I want to grow all my veg seedlings in there, cabbage, sprouts, broccoli, spring onion etc. Some of the seed packs say plant indoors Jan/Feb /Mar, does an unheated greenhouse in say March, count as indoors, I have no window sill (all very narrow) or suitable place light enough indoors to start them off. I've noticed at the moment its about 5 deg above outside temp in there. Also is it ok to 'chit' potatoes in there?
Tried to use a 'daylight lamp' in my outhouse to grow seeds once, but they were still extra 'leggy'. Any thoughts anyone? Thanks.

[rowlandwells]

we used to heat our greenhouse when we started seed sowings around February we used an old fashioned heater that burned solid fuel  wood or coal though cast pipes we had to light it in the early morning and keep it going all day then at night we had to supplement the heating with a calor gas heater and although the cast pipes heated under the staging worked out very well it proved to be to expensive to run

so we now start our sowings around early March in a cold greenhouse its a bit later than i would like but we haven't lost anything by doing this and if the temp goes down then we cover up with fleece not a problem and all our veg seed is greenhouse raised

and our seed potatoes there kept in bags in a frost free place till the weather gets a tad warmer then we box them up in chitting trays and stack them in the potting shed again cover the trays with fleece if temp falls never had any problems doing this and we never have any supplementary lighting or heating

[al78]

You should be ok starting the hardier veg like leeks and brassicas in the greenhouse, then gradually acclimatise them to outdoor conditions when it gets a bit milder. The problem with chitting potatoes in there is they might get damaged by frost, and there might be too much light, so I would chit them indoors. You don't need much space to chit potatoes indoors, enough space for a row of egg boxes.

I wouldn't recommend keeping brassicas in the greenhouse through the whole season. Brassicas don't like heat, and it will get too hot in the greenhouse (mine reached over 40C several times last spring). You'd probably have problems with leeks as well, heat stress might induce bolting.

[New shoot]

I use a cold greenhouse for much of my seedling production.  I’ll start with a few early sowings of summer cabbage towards the end of this month, plus broad beans and probably some spring onions as well.

February (depending on how cold it is) will be more sowings of brassicas, onions, leafy greens.

March and April are still variable, but you can sow most hardy veg.  You might have to hang on for tender stuff like french and runner beans, tomatoes and the like.  Indoors generally means around 20 degrees C for germination, so a cold greenhouse is not always warm enough.  They are not cheap but a indoor propagator with grow lights could be the answer.  Something like this :

https://www.suttons.co.uk/garden-equipment/all/geopod-heated-propagators_mh4723

I shuffle my hardy stuff out into a cold frame as it gets to a decent size, so it might be worth looking into those as well or make your own.  You can also do a lot to protect tender stuff inside a greenhouse.  I have one of those cheap 4 tier plastic covered mini greenhouses set up inside mine early on in the year, plus fleece on hand.

You can chit spuds in there, but you do need to make sure they don’t freeze or cook.  I use my shed now as it has a window, but in the past I have laid out seed spuds in trays on the benches from February onwards.  I used a double layer of fleece underneath them, then had a double layer to cover them.  That still lets enough light in to chit them.  If it suddenly goes warm, you need to get them uncovered fast and out of the sun. 

So not ideal for everything, but with a bit of imagination you can make most things work for you 

[bobbyt]

Thanks everyone for the useful advice and comments. I don't intend growing leeks/brassicas etc in there, just start them off to plant out when its warmer, March/April time. While on that subject about leeks, do you need a deep seed tray to start them off in, I tried in a normal seed tray last year but they didn't really take off, may have sown them too late?

The only thing I am considering growing in there are peppers maybe. As you said, it can get up to 40 deg in there in summer, even though I have auto openers. Last year I put some shading netting on the south side, which seemed to help a bit. Thanks.

[mumofstig]

While on that subject about leeks, do you need a deep seed tray to start them off in

Yes, cat litter trays are ideal..

https://chat.allotment-garden.org/index.php?topic=26363.msg312300#msg312300