In the Potting Shed – Seed Sowing

A busy weekend in the Potting Shed while the weather was awful means I have got a lot started undercover. I feel that the garden year has actually got going now the sowing is underway. What I’ve sowed.

The weather on Saturday was not good. Wind and rain which felt even chillier than the 6ºC the thermometer was reading. Sunday was only a little better – perfect for the potting shed, though. Pop the fan heater on for half an hour to take the chill off and find some lively music on the radio to keep me bopping as I’m potting.

I suppose I should be truthful. The first hour was spent tidying up, a job I’ve been putting off for months. I need to give the windows a clean as well but that’s not a job for windy wet weather. Once the decks were cleared for action, the real work could start.

Energy Efficiency

Propagators with Grow Lights

3 Tier Vitopod to rear, 2 Tier Vitopod with lights centre and Geopod to right

This year I’m trying to be efficient with power and seeds. The cost of power is crazy now, which makes running the propagators expensive. In the past I’ve tried to be efficient to minimise power consumption on principal but this year I’m really trying.

Starting seeds that will be pricked out like brassicas and tomatoes in 10cm pots rather than trays es a lot of space in the propagator. Going for lower temperatures than the absolute optimum for germination saves energy as well.

Incidentally, I’ll still be using my grow lights when beneficial. They don’t consume much additional power as the heat they produce is utilised, reducing the amount the thermostatically controlled propagator uses.


It seems that the price of seeds has really shot up. Not so much the open-pollinated varieties but the F1 varieties are generally through the roof. It was expected when the pandemic struck and so many took up home growing but the price inflation is continuing now.

All the more reason to get the most out of every packet of seeds. Use up old seeds if there’s a reasonable chance they’re still viable and carefully store the remainder from a pack after sowing. See seed lifespans

Tomatoes and Cucumber

Tomatoes Cucumbers Seeds in Geopod Propagator

Tomatoes and Cucumbers sown in pots in the Geopod Propagator

I’ve sown five types of tomato this year:

Tomato Black Opal

Black Opal – a lovely flavoured black tomato. I’d about 4 seeds left in a packet that should have been used by 2022 – sowed the lot. I only want two plants and should get that with luck.

Tomato Sungold

Sungold – a favourite variety and, like the black cherry, past the official use-by date. Again I’m looking for 2 plants, a one in three germination rate which shouldn’t be a problem.

Tomato Crimson Crush

Crimson Crush – a standard tomato like Gardener’s Delight bred for outdoors with good blight resistance and a proper tomato flavour. Sowed the whole pack of 10 as I want to run a fertiliser trial later in the season.

Tomato Crimson Blush

Crimson Blush – a large beefsteak tomato with good flavour and blight resistance too!

Tomato Crimson Plum

Crimson Plum – for my money one of the easiest and best plum tomatoes. Great for cooking and for storing either bottled or as frozen pulp.


Sowed 3 pots, 2 seeds per 9cm pot, of Partner a gherkin type cucumber. I’ll thin to one plant per pot. They’re a lovely little cucumber which my grandson happily eats as a snack on a hot day. We do get the odd hot day in Wales, honest!

All of those went into my small Geopod Propagator set at 21ºC which is within the optimum seed germination temperature range for both cucumbers and tomatoes.

Broad Beans

Really broad beans could be sown directly but the weather’s so wet that isn’t an option. Anyway, you get a better germination rate sowing undercover. Losses due to rot in wet ground and pests like mice can really hit outdoor sowings of broad beans.

Sowed Karmazyn in square 9cm pots which filled the base of one of my large Vitopods. They’re a pink bean rather than green with a great flavour and they freeze well. We’re out of stock, unfortunately.


Double Stack in Vitopod

Double Stack in Vitopod

The leafy brassicas all have an optimum germination temperature range of 10 to 25ºC which fits well with the broad beans’ 10 to 15ºC so I placed them on top of the broad beans in the Vitopod which is set for 13ºC. The extra height with the second side layer enables me to have two layers – gold star for efficiency for me!

As soon as the seedlings start to emerge the beans will go outside and the brassicas will move onto the greenhouse benching once pricked out. Then those seedlings can go in the coldframe to harden off prior to planting out. That should free the Vitopods to take on the tomatoes when they’re pricked out. Well that’s the plan and we’ll see how it works out in practice.

With brassicas, I mix a little dolomite lime into the compost. Brassicas prefer a high pH around 6.5 to 7.0 and most commercial compost is 5.5 to 6.0

Brussels Sprouts

Sowed the remainder of a pack of Brodie, an F1 that has done well for me over the last couple of  years. This sowing finished the packet so next year I’ll be growing Evesham Special which has served well since being introduced in 1920.


Cabbage Greyhound

A fast growing, compact, conical heirloom cabbage. Monthly successional sowings to produce a couple of plants per month through to November. Similar to Wheeler’s Imperial

Cabbage Red Acre

A decent red cabbage, similar to Red Drumhead.

Cabbage Earliest of All

A ball cabbage, quite similar to Golden Acre but faster as the name suggests. I’ve a lot of these seeds so I’ve sown in a half tray rather than a pot. What doesn’t get pricked out will be left to grow on for a bit as a treat for the chickens.

Cabbage Hispi

These were left over from a promotion, put in a sealed sweet tin and forgotten. That’s why I’ve got 100 packets with a sow-by on the packet of 2018. Hispi is an F1 that’s like an improved Greyhound or Wheelers Imperial.

The question is whether the seeds are still viable six years after the last sowing date. I expect the germination rate may be very low at best. To test them out I sowed 3 half seed trays with 5 packets (approx 275 seeds) per tray. Interesting to see what happens and how many, if any, show.

Calabrese (heading broccoli)

Sowed the remainder of a packet of Green Magic from 2021. Decent flavour and easy to grow (it has an RHS Award of Garden Merit) When the big head is cut it produces useable side shoots until end of season. Great fresh but it also freezes well.


Cauliflower All Year Round

Started by sowing Cauliflower All Year Round – it’s a very reliable cropper that can be sown and harvested most months – depending on the weather, of course. Introduced in 1933, there’s good reason it’s still around.

Cauliflower Skywalker

Sowed Cauliflower Skywalker – an F1 (organic as well) the seeds were sent to me as a sample. Looking forward to seeing how they work out.

Lettuce & Spinach

In the Bustaseed I sowed a selection of lettuce along with some Perpetual Spinach.

Bustaseed Tray with modules in use

Bustaseed Tray with lettuce and perpetual spinach sown in rows.

Little Gem

First off I sowed Little Gem – they’re perfect for us. Easy to grow, good flavour and they don’t need too much room. Strange to think the same lettuce has been grown for over 140 years. Hard to top perfection!

Black Seeded Simpson

Next some Black Seeded Simpson I received as a gift. They were introduced in the same year (1880) as Little Gem so must have merit to just be here.

Lettuce All Year Round

My final lettuce is All Year Round which was introduced in 1829 – won’t be long before it’s 200 years old!

Apart from starting some parsley off in small pots, that’s it for the potting shed for a bit. Next up to the polytunnel but that’s for later in the week.

Posted in Allotment Garden Diary
7 comments on “In the Potting Shed – Seed Sowing
  1. Nick O'Doherty says:

    Hi John

    I am using a big heated propagator for the first time. In a cellar. Plenty of veg seeds in module’s in there. I know to remove them into light when they germinate, but what % should I see popped through before I remove them? So let’s say it’s a 5×4 module with 5 seeds in each station. Should I take the module out when I can see 10 shoots poking through, on the basis that the others will be out shortly? Or wait till I can see more?

    Thanks for any advice on this subject.


    • John Harrison says:

      Hi Nick
      What you see is seedling emergence but under the surface the rest will have germinated or be germinating. So as soon as a couple pop their heads up, move into the light.

  2. Jasmin says:

    I use fleece to protect my overwintering dahlias as I leave them in the ground with a good success rate. Only problem – the fleece gets shredded by our pesky crows and magpies who use it as bedding material by taking great big chunks out of it! Jasmin

  3. Susan says:

    You could always open a farm shop for all Hispi cabbages!

    I like the hanging basket tomatoes but my partner likes Gardeners Delight so I sow seeds for mine but buy one GD plant and then let a couple of side shoots grow and then plant them. It works well as we then get more late tomatoes.

  4. May Ling Waddingham says:

    Can I have advise re: sowing chillies.
    I started mine in Feb using a windowsill propagator from seeds taken fresh chillies. So far I can only see 1 seed germinated from over 1 dozen seeds. Any advise please?

  5. Richard Reyn olds says:

    My Chinese wife and I were married in her home city, Chongqing,, but has now lived here me here in England now for the past 12 years,,, she was born in Chongqing and went to university in Chengdu,,home of the Panda Sanctuaries,, but also a major center of chillies and related products. Some are light and delicate,,most of which are exported,, the real hot varieties are sold across China and many other Asian countries too. One day when walking past a processing/ fermentation company, I paused to watch some guys stirring massive great earthenware vessels,, OMG,, even from 20 yards away, the aroma/fumes made eyes stream tears and my nose run like a tap!!!
    YueLi now grows several varieties here in our polytunnel at our Allottment,, but although I take care of them as they grow and ripen,,, I leave harvesting jobs to her, she is a genius at most things “Chillies”,, having now sought out different varieties from Seed companies here in UK, she really misses the HEAT.!,
    Feel free to email me if you want answers to questions about growing in UK.

  6. Richard Reynolds says:

    I note a comment from May Ling Waddingham,, would that be in Lincolnshire?
    Yue Li and I live in North Lincolnshire,, 15 minutes drive from The Humber Bridge. Email us if you need advice/ help with growing Chillies,, zai jian, Richard.

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