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Trials Part 1: Selecting Seeds and Sowing

Updated: May 24, 2023

For Zwetsloots Floriculture, 2023 is to be the great year of trials. We are in the process of growing a great range of annuals and perennials to gather as much information as we can to inform our plans for next season. This means that 2023 is also the year of the spreadsheet and data! We're seeking the answers to a large numbers of questions including which varieties and cultivars:

- are best suited to growing on our soils and climate

- we enjoy growing and handling most

- germinate well using our current set up

- compliment one another in shape, texture and colour in a bouquet

- have the best vase lives

- sell well locally

- dry successfully

- we enjoy bunching and arranging

Selecting Seeds

Seed selection began with an idea of the varieties we both liked. I tended more towards the annuals whilst Pa focused more on perennials and foliage plants. My list included snapdragons, especially the salmon and bronze shades. I also really like cosmos, although was initially sceptical about the vase life of them, and was curious to try zinnias as I've never grown them before; I like the idea of having dahlia-esque flowers before dahlia season began and was drawn to the newer, less brash varieties such as the Queen and Benary's Giant series.

Pa began with a longer list which included delphiniums, achillea, rudbeckia, bells of Ireland, lady's mantle, eryngium, phlox, salvia, gypsophila and dahlias. Many of these flowers, such as the phlox and delphiniums, were chosen simply they're ones he has always loved. Eryngium was another, but one he has also previously struggled to germinate so he saw these as a challenge as well. The salvia was selling cheaply at Spalding auction. The atriplex is mentioned a lot on flower growing podcasts as a good filler, one that self-seeds and grows fast.

Selecting varieties of these species became a totally absorbing and never-ending but utterly joyful task. Beginning on pinterest, I pinned all of the shades I liked, naturally forming a palette, and made lists of cultivars, before researching stem length and discarding any that were unsuitable. Like many, I was drawn to the oranges and pinks and all of the shades in between: the salmons, peaches, apricots, blushes. The search broadened with trawling through some of the big seed company websites; my list of potential varieties grew and grew as I came across more beautiful and well-reviewed flowers for cutting and foliage. The Chiltern Seeds 2023 Spring Edit which focused on flowers for cutting and drying was especially inspiring to me, organised as it was by colour, and by this point I was really struggling to exercise any kind of discipline! The pretty pictures in the depths of winter were all just too much of a temptation.

At this time, a new idea began to grow: the idea of growing a small range of flowers for drying and selling on Etsy this year. Despite the initial plan to experiment this year and save the selling until 2024, my enthusiasm and impatience to start selling had grown dramatically since beginning the business in September. A dried flower range could be small scale, would in theory be less pressure because I'd be dealing with a dried product rather than a fresh one, and it'd be a great confidence boost and motivator if we managed to make a profit in year 1. I also have 6 long weeks of summer holiday because I'm a teacher and I'm keen to put to good use.

As a result, many classic everlasting flowers such as helichrysum, gomphrena, craspedia, canary grass and bunny tails, were all added to the list. I also began to see new potential in some of the other flowers we'd already chosen, especially Pa's eryngium, achillea and gypsophila.

Once the list was finalised, I tried to purchase mostly from the cheapest but well-reputed seed suppliers. Some seeds such as the gomphrena and helichrysum were purchased from small eBay suppliers because I struggled to get hold of them elsewhere. I kept a record of the suppliers in case the seed didn't germinate and I could avoid purchasing from the same place again.

My Seed Set Up

Most of my seeds were surface sown in 8x12 3cm plug trays in March. To avoid wasting seed, I used tweezer to position the small seeds and cocktail sticks for the fiddly, teeny tiny antirrhinum seeds.

I always enjoy handling seeds in all their strange shapes and sides. This year's favourite seed was Scabiosa stellata 'Sternkugel' which initially resemble shuttlecocks and then turned into little skirts on the stems of the seedlings when they germinated! They also make robust, thick-leaved seedlings which made me favour them over my snapdragon seedlings which buckled and crumpled beneath the lightest of forces.

As I don't have a greenhouse and my windowsills are too shallow for wide plugs trays, I set up an 80cm wide grow house with four shelves and a plastic cover in the utility room. I attached full spectrum grow lights and put them on a 12 hour timer.

I was initially worried about the temperature in the room because it was hovering around 12 degrees celsius, often dipping below. Most seed packets, especially those of tender annuals like zinnias and cosmos, state that they need much warmer temperatures to germinate. However, to my delight, and with the exception of the gomphrena, all of the germination rates were surprisingly high. I had sown my teensy antirrhinums in twos which meant I had to thin almost every plug out again and could have saved half of the seed!

Owing to a shortage of space in the grow house, the antirrhinum and helichrysum were soon pushed out and put into the cold frame in the garden in the day time and brought in at night if the temperatures were due to be in low single figures. As I tired of traipsing in and out every night with numerous trays, the seedlings were made to endure cooler and cooler temperatures and so became hardened and robust from a small stage and grew strong.

I went away for a week at the start of April and so they all got to live in my partner's office temporarily!

Pa's Seed Set Up

Pa's set up was quite different to mine; it was larger scale and produced more consistent conditions. He sowed most of his seeds in seed blocks on a heat mat in his greenhouse. He used a 2cm soil blocker in long trays which meant he could fit a lot of seedlings into a small space and these were watered gently to avoid disintegration.

The greatest challenge with the soil blocks were them drying out too quickly when the day time temperatures increased.

a table of seedlings growing in seed blocks in a greenhouse


My seed set up wasn't ideal because of the constant moving about. I lost a few because they got knocked about, crushed by heavy rain and a few slugs managed to reached them in the cold frame.

Next season, I'm keen to spread my seed sowing. I want to try sowing hardy annuals in late summer and autumn this year and to get them established in the ground before the first frost. After reading 'Cool Flowers', I want to use the Lisa Mason Ziegler method of sowing them in soil blocks just 2-3 weeks before planting them out. The idea of planting them at a much earlier stage sounds really appealing because it eliminates weeks of worrying about them drying out, taking up space or getting damaged by rain or cats. They should also work better in my smaller space because they'll all fit on the shelves of the grow house and/or my windowsills. And, the biggest appeal of all, I'd love to be able to be picking my antirrhinums and helichrysum this time next year instead of planting them out!

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