Seedlings - indoors vs. conservatory

[ourarka]

Just wondered if there was a general opinion on where best to raise seedlings over the next couple of months. I am talking about tender and semi-tender things (including veg) including things such as cannas, coleus, bedding, tomatoes, chillis etc.

I have the option of a reasonably bright spare room, kept around 18C all day and all night, or an unheated conservatory which is very bright and ranges from around 10C at night through to 18-25C during the day (depending on cloud cover).

Is there a rule of thumb .... or would everything rather have the better light with lower night time temps?

[ourarka]

.... just to add .... I am talking about post-germination (which is done in a propagator)

[Steph]

I'd say let them struggle in the conservatory, makes stronger plants.

[Mowgley]

I'd keep the coleus, chillis and toms above 10'c, everything else yo mention will be fine

[ourarka]

Even the conservatory is always above 10C, unless we get a very cold snap, so I am thinking the conservatory may be best, even though there is a larger diurnal swing .... it is significantly brighter (with all round light as well)

[Kristen]

I no longer use windowsills / spare bedrooms for seedlings - not enough light. If we get a rubbish spring like last year then nothing like enough light

I germinate seeds either in boiler room 25-30C, ordinary room 20C, or spare bedroom 15C plus a combination which also includes fridge for things that need stratification.

Some things then want very little heat, so they go straight out to unheated greenhouse (can get frost, but unlikely from end Feb onwards) or conservatory (definitely frost free), but for the rest they go under lights.

At some point in March (depending on the weather) I move the lights to a plastic tunnel in the conservatory, and run the lights overnight (Metal Halide, so also generates heat, but otherwise supplemental heat might be needed. I want 16C Minimum). This gives the plants daylight in daytime (albeit having to pass through both conservatory galls and tunnel plastic), and supplemental light for 6 hours each night.

For things that have tiny seedlings, like Coleus, I think this makes a huge difference. For Runner Beans / Ricinus, or some other thug like that, it would be a waste of time, space and money

better light with lower night time temps

Yes. Heat with poor light will cause leggy growth, light with no heat will, at worst, cause the plant to sit still, but if it does grow the the growth it does make should be sturdy.

But I'm greedy, I want Heat and Light and thus be able to have an expectation of how much growth I will get.

[ourarka]

Some things then want very little heat, so they go straight out to unheated greenhouse

How do you differentiate? Does this apply to many of the 'tropical' plants/veg, even those considered pretty hardy?

[Kristen]

How do you differentiate?

I look them up - takes ages (I grow several hundred different specieis / varieties each year).

If germination details are on Tom Clothier's site I just go with that and don't look anywhere else (he probably isn't always right, and I may have some zero germinations as a result, but I live with that).

Spreadsheet for all the seeds, date when I intend to sow, and actual date (plus germination & prick out dates, and number of plants (only where the packet of seed had very few, otherwise I just enter "Lots"). If there are only 5 seeds in a packet handy to know if they all germinate, or only one, in case I want to grow some more next year - although germination percentage may not be the same from a different batch of seed next year, of course.

I then adjust sowing dates - I only have 1st and 15th of the month as sowing dates, for things that are not so important to me I put down as 2nd, or 3rd etc. so that when I sort by date those with the 1st date get done first, and if time those with 2nd / 3rd date are done next. Come 15th I sow things with that date, even if some of earlier 3rd date still not done - they weren't a priority in the first place

Plants I always grow, like Ricinus, are colour coded so that I don't accidentally overlook sowing them.

Takes me most of the winter to complete the Spreadsheet

Spreadsheet also has columns for what temperature is required etc. many things (that I chose to grow) are not simple - so they might want 20C for 2-3 weeks, then fridge for 4-6 weeks, then a certain temperature for germination - and if still no germination then repeat the fridge cycle. There is then a temperature for after germination. I have columns for all these possibilities ('coz at times I need to sort, or filter, by them to work out how I am going to organise the upcoming task - e.g. it can help to have all the ones that need soaking for 24 or 48 hours to be started off on Thursday ready for sowing over the weekend).

For things with complicated required I write out a label like this:

... 20C for 2-3 weeks,
... fridge for 4-6 weeks
... 20C Germination
... 4 weeks repeat fridge if no germination
... 16C Prick out

and when I sow them I write today's date in the first slot, and add 2-3 weeks and write that on the second line - i.e. that is the ideal date for the next action. Generally these are minimum times (doesn't matter if they are late going into the fridge, but they MUST stay in the fridge for at least that many weeks), so lets assume it actually tales me 4 weeks before I put it in the fridge, so AT THAT TIME I write the date (adding 4-6 weeks to today's date at that time) for the "20C germination" line - i.e. the date when the next action should be performed.

I use small plastic bags for these. Personally I fill them with a small quantity of Vermiculite (enough for all the seeds to be well mixed in, but not so much that the seeds have masses of Vermiculite - otherwise when they are subsequently sowed it needs a large surface area for the Vermiculite and, perhaps, only 5 seeds).

Other people use kitchen paper of coffee filters (in plastic bags). I've tried that and had very poor results, I suspect I had too much / little water, or not enough air, and (for me) I find that vermiculite is more tolerant of both those problems.

Sometimes the seed stays in the bag until germination, sometimes it germinates before I am expecting it (e.g, during the first stage, before I even get to put the bag in the fridge ) but sometime the Germination phase is long enough that I just spread the vermiculite & seed on top of a pot of seed compost and leave it to get on with it.

This is what I do for complicated things - i.e. things that typically require stratification. I doubt there are any Tropicals that require that treatment, but there are "Unusual things" which us Exotic growers may choose to have in our Exotic borders that, whilst not Tropical, might need all this who har. For example you might choose to grow something like Cardiocrinum giganteum from seed (rather than paying £10 a bulb for them )

Tom Clothier says : Sow at 18-22ºC (64-71ºF) for 2-4 wks, move to -4 to +4ºC (24-39ºF) for 4-6 wks, move to 5-12ºC (41-53ºF) for germination

Elsewhere says they are slow to germinate, so after stratifying I will spread the vermiculite & seed on a small seed tray and leave it to it.

Where I have only 5 or 10 seeds I put them in a 9cm (square - more space efficient) pot. I use only Seed Compost (John Innes, soil based), never multi purpose - too rough, and probably too much fertiliser. I stick the pot in a zip lock bag and then put it at the required temperature. In the bag it won't need any more water for a month or two (the water cannot escape the bag) and most things will have germinated by then. I open the bag once it has germinated and move it to light / correct temperature for "after germination".

Vegetables are usually much easier - just sow and wait However, many of those have ideal temperatures. Brassicas don't like heat, onions like some heat to germinate, and then no heat. Tomatoes need some heat to germinate, and then some heat to grow. Ideally Tomatoes should never fall below 10C (e.g. after planting out in greenhouse) otherwise they will stall.

"Hardy" doesn't make any difference. In fact lots of stuff that is hardy is more difficult to germinate, because it has inbuilt germination inhibitors to prevent it germinating until spring (hence putting it in the fridge for "stratification"). Some have a randomisation too, so that if Next Spring is dreadful, and all the seedlings die, some of the seeds are programmed not to germinate until the following spring. Tropical plants can generally just germinate when there is heat and water - so might be regarded as "easier". Although ... with Bananas you'll be very lucky to get as many as 10% of the seeds to germinate, and they like a temperature change between Night and Day to trigger germination.

Enough already, I'm sure !!!