PROPAGATORS

General tips / questions on seeding & planting

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Allan
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Postby Allan » Mon Mar 20, 2006 3:19 pm

If the polythene is reasonably new I wouldn't expect even two thicknesses to make all that difference in the light. The typical transmission of a single sheet of UVI film is 97% so 2 layers brings it down to 94%, hardly anything to worry about. Possibly of greater concern to me would be soaring temperatures under full sunshine, not only at the peak but the maximum to minimum could be enormous. If you could have some means of variable shading this could be overcome. I wounder what Matthew Harrison of Northern Polytunnels would have to say about it, I am on quite good terms with him.
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Letter from RHS

Postby Guest » Tue Mar 21, 2006 6:23 pm

This is the info that I got from RHS.
It plugs some gaps but leaves others
For instance lettuce are known for having a notably low maximum temperature as our previous data shows.
I think it will have to be an ongoing project.
Guy Barter writes for the magazine
____________________________________________________
Dear Mr Day

Thank you for your email concerning vegetable seed data. I assume that you mean temperatures, emergence times and losses in seeds sown. This very well documented in the literature. In essence it is folly to sow most hardy veg, beetroot, carrots, parsnips for example until soil temperatures reach 8C or more. Some have a lower theoretical germination temperature - lettuce is very tough and will germinate at 0C, but practical gardeners hold on for higher soil temperatures. The higher the temperature the faster the emergence and the lower the losses from cold, pests and diseases. (I am afraid that Fahrenheit is a mystery to me).

Tender vegetables, tomatoes, peppers, cucumbers, need soil temperatures of 12C or more. But this is seldom an issue as these crops are usually raised in a greenhouse where the temperature can be controlled. I would always aim for 20C for these crops. If you must sow outdoors do so in June.

Thus, you might expect germination temperatures to be reached in open ground, light soil in southern England in late February for hardy veg. Here carrots and parsnips will take about 6 weeks to emerge, and have 90 percent losses. By March soil temperatures will be on the up, and carrots might emerge in 4 weeks with 50 percent losses, by April you might get a 14 day period to emergence and 30 percent losses and by May/June 10days to emergence should occur with less than 20 percent loss rate. This year is so cold that we are a month late. Clay soils are always a month or even 6 weeks later than sandy soil.


You will see from this, that germination temperatures alone are not very helpful. The trick is to consider the overall seedbed environment and likely weather before emergence and make you decision on when and how much seed to sow based on this. If in doubt wait, as later sown crops catch up early sown ones to a very large extent.

Alas, excessive heat, >25C, is seldom a problem in Britain! However, lettuce sown in summer should be sown in late afternoon so it experiences cool night time temperature as it imbibes moisture.

However, this is all very well for a horticultural scientist like myself to say – consider the attached list as a guide which might be helpful to less technically minded gardeners.

I hope this information helps. If you want to paste it onto your forum I don’t mind as long as you attribute it to the RHS.

You might be interested to know that we also provide a wide range of self-help facilities on the website. Please see details below.


Yours sincerely
Guy Barter

Horticultural Advisor


Aubergine 20C
Artichoke 20C – but I find they do fine sown in May outdoors
Asparagus 20C indoors – but I find they do fine sown in May outdoors
Asparagus pea 20C indoors, 12C outdoors
Beetroot >8C
Cabbage tribe >8C outdoors or unheated cover, >15C under heated glass
Broad bean >8C
Carrots >8C
Celery/Celeriac >15C under glass
Chicory >8C
Cucumber 25C
Endive >15C in mid-summer
Fennel >15C in mid-summer
Lettuce >8C
French bean, runner bean: >12C – they hate cold soils with a vengeance
Leeks & Onions >8C outdoors, >15C indoors
Melons >20C
Okra 25C
Parsnips >8C
Peas >8C, but they loath wet soils
Peppers and chilli 20C
Tomatoes 20C
Radish >8C
Spinach >8C
Marrow , squash, courgette and pumpkin tribe 20C indoors, >15C outdoors
Sweetcorn 20C indoors, >15C outdoors
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Allan
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re "guest"

Postby Allan » Tue Mar 21, 2006 6:30 pm

I expect everybody will have spotted who the "Guest" was.
Once again this "Auto" log-in has failed and I didn't spot it in time.
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daxtell71
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Re: PROPAGATORS

Postby daxtell71 » Tue Jul 06, 2021 3:41 pm

I am just learning about propagators so this thread is very useful. Thank you :-)
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How many beans make five? :lol:
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Johnboy
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Re: PROPAGATORS

Postby Johnboy » Wed Jul 07, 2021 11:30 am

Well there's a blast of the past if ever! The original posting was when this forum was very active and a lot of people gathered sensible information and I hope they are all still actively growing some wonderful vegetables.
This is in the days when Allan and myself had continual spats on line. In real life we were actually very good friends and both professional growers. Sadly Allan is no longer with us but I still plod on although now I only advise a team of market gardeners who seem to be gathering an awful amount of customers this year.
I am very greatful to Daxtell71 for actually bringing this subject again as an example how this forum should strive to operate. I have read the entire thread and there is, all these years on, still plenty that has transpired in the time.
I still stand by my original tetter but there is still plenty to be discussed on the subject.
Thank you Daxtell71 for refreshing my memories of the old days. Should you wish to PM on anything be quick because at 91 I'm not going to be around much longer.
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Diarmuid
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Re: PROPAGATORS

Postby Diarmuid » Wed Jul 07, 2021 6:05 pm

Dear Johnboy,
Thank you so much for your contribution. I have re-read it completely and found it so interesting, containing so much good advice from you. I was unable to log into the forum for a long time so opened a new account. I was probably one of your "Readers" and I am still referring to your original guide. Thanks a lot.
Regards,
Diarmuid.
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kameshbhai511
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Re: PROPAGATORS

Postby kameshbhai511 » Thu Aug 19, 2021 8:39 pm

There was one such in the DT Brown seeds catalogue. I kept a copy and did some work converting the temperatures but it got rather messy because of the crudity of the original data. When they've two seed leaves up then the clear lid comes off and 2 or 3 days after that,depending on what it is and how well it's getting away,I remove them from the heated base and stand them in the greenhouse in good light conditions to firm up a bit before I pot them on.Also important is whether the seeds need light to germinate, and a mention of seeds that need special treatment to break dormancy spice money login
myfiosgateway
Last edited by kameshbhai511 on Sat Aug 21, 2021 10:04 am, edited 1 time in total.
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Johnboy
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Re: PROPAGATORS

Postby Johnboy » Thu Aug 19, 2021 11:22 pm

Dear Diarmuid,
I am afraid that age has caught up with me and I cannot remember your previous name used. I remeber you having difficulties with Sweet Corn all those years ago and sending some seed that had just germinated well for me so should have done for you.
Please PM me if you have the time.
Sincerely,
JB.
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Primrose
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Re: PROPAGATORS

Postby Primrose » Wed Aug 25, 2021 7:14 pm

I got rid of my large propagator many years ago. It was a gift, and one of those large square ones which used a base of hot water as a heat source, and without a greenhouse and only a bay windowsill it just took up too much space for the short amount of time it was in use.

I,ve germinated small quantities of seeds in our airing cupboard (with a yellow post it note on the door to remind me to check them every morning & evening!) and even balanced four pepper & chilli pots on two hot water bottles with covers on them to speed germination which to my surprise worked very well although reheating the water in the bottles twice a day was rather a pain.!

I think Johnboy is absolutely right about moving them from the heat the moment they germinate. I think a lot of people have probably lost plant or grown seedlings whixh have been too weak due to excessive heat exposure. A few hours literally can make a difference between a strong seedling and one that has already grown too rapidly ever to recover.
Last edited by Primrose on Thu Aug 26, 2021 9:48 am, edited 1 time in total.
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Geoff
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Re: PROPAGATORS

Postby Geoff » Thu Aug 26, 2021 7:25 am

I've found combining heat and light is the way to use a propagator successfully.
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Johnboy
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Re: PROPAGATORS

Postby Johnboy » Thu Aug 26, 2021 4:37 pm

Many vegetables simply need ambient temperature in a cold greenhouse where they get the light without any additional heat. Growing plants is not a race and they mainly give a far better plant if allowed to take their time doing so. Plants that are all foliage generally lack the root structure to support them when planting out and the result is a massive check in their growth and that follows right throughout the life of the plant. Using propagators do not necessarily give you an advantage in many cases it is quite the reverse.
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