Planning for Growth

‘Tis plant-growing time. We’re all madly sowing seeds (or buying plug plants or a mix of the two) with abandon. Well, the flower growers are; veggie people are probably getting ready to plant their stuff out now. They’re much more hardy types and like to get in early. But I’m rabbiting on about flowers, having given up veg growing.

I wonder, though, how many of my gardening compatriots behave like me – grossly underestimating the space all the growing plants will need whilst even more grossly overestimating the space we have available! However much space you have, it’ll never be enough. At the beginning of last year I had a 5ft greenhouse. By the end of last year I had a new 8ft greenhouse and I’m now wishing I’d gone for an easy fit 10 footer or even squeezed in a 12ft one.

Smart, eh?
Smart, eh?

But I know if I’d bought a 12ft one I’d now be wanting a 15 or even 20ft model.

You may also need to give thought to the temperature plants need in the early growing period. Begonias, for example, will grow far better if you can keep them at 13-15C.  So they’ll go in the greenhouse. Antirrhinums like cooler conditions. So they won’t. Some plants like warm days and cold nights. They’re cold-frame candidates.

We all have to get practical. So in this post I’m going to go on about how I approached a naughty word and how I’ve utilised my growing space effectively. The naughty word is “planning”. The sub-text is “organisation.”

I can split my plants into three broad groups: perennials, hardy annuals and half-hardy annuals. Hardy annuals are the easy ones. They’ll cope happily with being sown in the ground in autumn or early spring. But I have a spanner to throw in the works – resident cat. He likes curling up on any bit of bare soil he encounters. By bare soil, I mean anything that doesn’t have at least six inches of growth on top of it. Enter cloches – big ones a metre long and about 40cm wide and tall. Hardy annuals can now be removed from my management programme. They only require enough ground to grow in and a bit of thinning out. It’s also a good idea to scatter a few organic slug pellets under the cloches. And don’t forget to water under them too.

Now think about perennials and biennials. The number that flower in their first year is limited. So why rush to sow them? Let’s take the humble foxglove. I’ve seen some seed packets go on about sowing them in the spring. The plants know best. They sow their own seed in the early summer. So wait till then. Eryngiums can be sown now but they can also be sown in May/June. They’ll still flower next year. So if your sowing and growing space is limited, hold off the perennials for now.

So we’re left with the half-hardies. You can split these into two groups – those that have a longish growing season and those that don’t. Antirrhinums and lisianthus are two plants that grow slowly. They really need to be sown no later than early March. But most half-hardies only need about 12 weeks tops between sowing and flowering. I usually plant out in late May/early June and they start flowering in middle-to-late June. Count back 12 weeks from then and you hit the spring equinox. That’s when I start sowing like mad.

I sow seeds in either 40 cell modules (left) or in mini-trays (right). Some plants don't like root disturbance so sowing two or three seeds to a cell then means I can yank out the weakest seedlings and grow on the best. The multi-trays mean I can sow 5 varieties of seed in the space of a single seed tray and have enough plants for my needs.
I sow seeds in either 40 cell modules (left) or in mini-trays (right). Some plants don’t like root disturbance so sowing two or three seeds to a cell then means I can yank out the weakest seedlings and grow on the best. The multi-trays mean I can sow 5 varieties of seed in the space of a single seed tray and have enough plants for my needs.

Also, through late March, April and early May, my adoptive babies start arriving – the plug plants I’ve bought to jump past the sowing bit. These aren’t really “starter plants” as such; those are a bit bigger and are usually bought as individual plants or small packs. My plugs arrive in trays of between 70 and 170 little plants. Meanwhile, the seedlings I’ve grown need potting on.

And so, having disposed of timing, we hit the accommodation issue. I’ll discount window sills as most here are narrow and I can only fit in three seed trays in total. One of those is in the bathroom which isn’t really ideal so practically that’s just two seed trays – a maximum of 48 plants. Nah! I’ll keep that space to sow perennials in May ready to prick out into pots in the space released by the half-hardies getting out.

Wall planters
Why so many plants? That row of five wall planters above the ladder takes 50. I have another 16. That’s another 160 plants. Then there’s the hanging baskets, beds ….

In an average year, I need to accommodate about 2,000 young plants. Apart from the greenhouse, I have two of these:

Chaselink Lean-to Planthouse. There are two sizes - large takes 20 seed trays and small takes 16 (or equivalent).
Chaselink Lean-to Planthouse. There are two sizes – large takes 20 seed trays and small takes 16 (or equivalent).

These are fixed to the south side wall of the house and are very sturdy. They’re also quite warm inside. And think – 20 seed trays could mean 480 plants romping away. I can also take out the shelves and use them for bigger plants! I might try tomatoes some time. There’s a water butt next to them so watering’s a doddle too.

Then there are these:

Mine have three shelves, each of which will take three seed trays (or equivalent). Note the wheels which allow me to wheel them in and out of the shed, greenhouse or garage at night to keep the plants snug.
Mine have three shelves, each of which will take three seed trays (or equivalent). Note the wheels which allow me to wheel them in and out of the shed, greenhouse or garage at night to keep the plants snug.

If you get the type that isn’t on wheels, consider providing a way to attach to a wall or fence. They aren’t that sturdy and a sudden gust of wind will topple them over. Some come with little fixings sown into the seams but I’ve found these will easily tear. Better to cut a couple of small holes through the seams and attach fixings to the framework.

I experimented with one of these:

Lovely idea until the wind blew!
Lovely idea until the wind blew!

My advice: Unless it comes with at least one guy rope on each corner, and preferably two, save your money.  It won’t survive any measurable wind! If you shop around, you will find that you can buy sufficient “wheelie greenhouses” to accommodate the same quantity of plants for less than one of the biggie plastic-covered things. And they’ll be a lot safer too!

Right! That’s the accommodation sorted. Now let’s think about how we get more into it.

Don’t believe all that rabbiting on about needing to grow everything on in 7cm pots. And avoid anything round – I finally gave up on round pots two years ago. Square is much more space-efficient and will also help to stop slugs and snails getting at your plants as the top edges are snug against the neighbouring pot(s). They found a way into my new greenhouse despite it being firmly bolted to a paved area and with a tight-closing door and vents!

You can get a lot more of certain plants into a given space if you mix up what you grow them on in.

Three "sizes" of cell trays. These are half-seed-tray-sized and I have a choice of 12, 9 or 6 cells. Using half-sized trays means I can turn them "inside-out" within a full-size seed tray to get better overall growth.
Three “sizes” of cell trays. These are half-seed-tray-sized and I have a choice of 12, 9 or 6 cells. Using half-sized trays means I can turn them “inside-out” within a full-size seed tray to get better overall growth.

I find that begonia semperflorens, for example, grow perfectly adequately in 12-cell half trays so I get the equivalent of 24 to a seed tray area. Tuberous begonias, on the other hand, seem to want more space so I grow them in 6-cell half trays. New Guinea Impatiens seem to like the middle road of 9-cell half trays. (If you insist on growing Impatiens walleriana, then 12-cell half trays will be fine for those too.) Fuchsias I grow in 7cm pots as they seem to like the slightly deeper rooting space. Sweet peas I sow and grow 5 to an 8cm pot (I don’t bother with those root trainer things which I’ve found keep falling apart). It’s not a case of “one size fits all”. And I rarely use anything bigger than an 8cm square pot except for perennials.

When it comes to buying the cell trays, I avoid the common makes like Plantpak because, often, you’ll only get a single use out of them – they tend to buckle and tear. Rather I buy from The Garden Superstore. They’re much stronger and I generally get about 4-5 years’ use out of them. As they’re “half tray sized”, they’re easier to move around without breaking in half and I can turn them around in the seed tray occasionally to let the air and light get at the plants in the middle. I also buy my pots and shuttle trays there – they have a very good square range – lightweight, cheaper ones for the plants you’re going to give away (or sell for charity) and a stronger version that you can reuse for many years for your own plants.

So with a little thought and a little planning, you’ll be surprised just how much you can accommodate within whatever growing space you have.

And if all else fails, there’s always the car!

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This post is dedicated to Jennifer, who inspired it.

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8 thoughts on “Planning for Growth

  1. I love the idea of using your car as a greenhouse. Bloody excellent John!

    I have a small garden and one of those 5-tier plastic greenhouses. We had to attach it firmly to the wall, with heavy plants at the bottom, just to stop it from being blown away in the high winds in the last year. Still, now it’s tied down, it does the job. And if I run out of room, well there is always the car.

    1. It’s a pain when I want to go shopping or to water the plants, though. But I’m hoping that the car will be rested this year. With my new greenhouse I think I can accommodate about 1990 plants which is about what I expect to end up with, give or take 10-20. I’m refusing to look in any more catalogues or to view emails ……..

    1. Thanks.

      This year’s plug plants are coming from Jersey Plants, Dobies and T&M – all trays of 30 or more plants. In the past, for larger plants (wot people call “starter plants” rather than “plug plants”) I’ve used Hayloft and Sarah Raven but not buying anything “big” this year.

      I did try Fothergills for trays of 70+ once but found that their plugs were so small I couldn’t poke them out of their cells cos the holes in the bottom were just too tiny.

        1. Variably! I have learned to buy only their high quantity trays 170 little plugs or 70 “value” plugs. I’ve bought their larger plants (24 plants or less in a pack) in the past and found they regularly get damaged in transit, either because the compost is too loose in the cells or too dry. In one case, a pack of 6 only had 4 plants in it – they blamed the courier! But I’ll give them credit for speedily replacing or refunding as I wished.

          Of course, if you are relying on a 24 pack of fuchsias and they arrive damaged, you may not be able to replace in time and so may have to buy 3″ pot-sized plants which costs a fortune.

          Conversely, T&M are great for larger plugs but, IMO, chronic for the little ones which come in tiny plastic strips, tightly sandwiched between two layers of plastic and rotting wet on arrival.

          Dobies are pretty reliable for any size of plug.

          If you can tolerate the gizmos, Bakker are pretty good for starter plant sized plugs too. Especially fuchsias. But those damned free gifts you always get …. Nuff said!

  2. Thank you, John! Very helpful. Do you ever find seedlings get too hot in the plastic wheelie things?

    1. Almost the entire front will zip open and can be rolled up and tied in place as shown in the photos. My wheelies are covered in clear plastic, not the “shaded” type but, with the fronts up, I have no problems with heat or sunburn. And being on wheels means that I can move them into a shady spot should I need to. Two of the wheels have “brakes” to stop them rolling about – you just need to place them in the front when putting things together.

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