Seed Starting by Germination Times

Over the next several blogs, I’ll introduce myself and the overgrown path that led me to cut flower gardening. Here is the first installment.

I am the eldest of three girls. This winter, I was charged with getting our parents’ house ready for sale. That meant that I left my home in Virginia, including my seed trays, and headed for the frozen north of Michigan in February. I was gone for a month and took the Floret Online Workshop and the Loudoun County Master Gardeners online classes from Michigan.

It worked out well as the house sold within 24 hours of listing. But that meant that I left my young plants in the care of my black-thumbed husband and my ideas stayed on my idea board.

Meanwhile, in the fall of 2021, we began a full tear-down and rebuild of our second story covered porch. Normally, I keep my young plants inside the house in the dining room bay window. This allows them limited sun exposure and easy access to check on their progress. With the construction, I moved everything to our unheated garage and put the grow lamps on timers. Seedlings left to their own devices grow leggy and wild! Here are my observations from this “life experiment:”

  • If you’re going to the trouble of automating lights, its equally worthwhile to rig up an automated watering system. I’ll cover this in a future blog.
  • Don’t waste tray space on certain hardy annuals that do best in your region as a biennial or that clearly say that the recommended germination method is by direct sowing.
  • If you’re starting various varieties of plants or different species in the same seed starting tray, go by germination times, NOT BY WHEN YOU NEED TO START THEM! I ended up with many seeds that didn’t have enough humid time under the dome to start properly which meant that others that grew fast were bent over or died due to damping off from being squished under the dome. COMING SOON! My recommendations for combining trays. My early seedling tray recommendations are below.
  • Remember to drop your grow lamps or shop lights low so that the seedlings don’t stretch for light. I also strongly recommend fans to tell the plants to strengthen their stems with the “wind” and vibrations.

Once the construction was finished, I was able to put up a seedling tower in mid-April for my heat loving plants like zinnias. These are the specs and my best efforts to make this a DIY opportunity for any other grower:

  • 24 inch wide x 4 foot long shelves – this allows the shelves to hold four 1020 (10” x 20”) trays
  • 4 foot long heat mats with temperature regulators
  • Adjustable height lighting with 1 LED and 1 fluorescent* shop lamps (see below about availability)
  • Electrical timers for the heat mats and fans
  • Jenius™ (made by me) fan bar with high velocity 128mm fans

Jen’s tray recommendations

Germination of early start (February here in 6b) hardy annuals (focal flowers likely will be bulbs like tulips or narcissus) with field growing on before last frost date (note that three may be fall sown for over-wintering plants like biennials allowing an earlier bloom):

TrayBouquet Category†Common NameLatin NameCultivarFlowering Category†Germ TimeDays to 1st BloomYield/plant
2SpikeSnapdragon Antirrhinum majusChantilly – Group 1MP14-21 days with light1007.5 [1]
1SpikeSnapdragon Antirrhinum majusCosta – Group 2MP7-14 days with light1106.0[1]
2FillerThoroughwax Bupleurum rotundifoliumGreen/GoldOHW; fall sow14-21 days10610.0 [2]
2FillerFalse Queen Anne’s LaceAmmi majusQueen of AfricaOHW; fall sow7-21 days6528.0 [3]
1DiskPot MarigoldCalendula officinalisPrincess GoldenMP5-15 days13614.9 [4]
1AirCorn Cockle Agrostemma githagoOcean PearlMP7-14 days703.0 [5]
2AirLove-in-a-Mist Nigella damascenaCramers’ Plum MP; fall direct sow10-14 days657.6 [6]
1DiskBachelor’s Buttons Centaurea cyanusClassic Artist Mix CornflowerMP5-10 days13918.1 [4]
2DiskPincushion Flower (annual)Scabiosa atropurpureaQIS formula mix CC10-14 days with light10017.0 [7]
1FillerCressLepidium sativumGreen DragonOHW3-7 days506.0[8]
† Source: Floret, LLC. “Online Workshop Course Book,” 2022. See Plant Spacing Quick Reference Guide (pages 102-103). Flowering category abbreviations: CC= Cut and Come Again; MP = Medium Producers; OHW = One-Hit Wonders

[1] 2013 ASCFG Seed Trial Report. Variety trialed was ‘Chantilly Velvet.’ The 2012 ASCFG Seed Trial Report has the variety trialed as ‘Chantilly Purple’ with a yield of 4.8 stems per plant.

[2] Stems Flower Farm. Costa Mix description. “Potential Harvest Yield: 6-10 stems per plant.”

[3] Wein, H.C. “Cut Flower Cultural Practice Studies and Variety Trials 2014.” Cornell University. Grower note in report: “Apparently growers plant in fall to get more vegetative growth before harvest.”

[4] Planter, K. “2017 Fresh Cut Flower Production: Completion Report.” 2018 Field Days Bulletin.

[5] Stems Flower Farm. Agrostemma ‘Ocean Pearl’ description.

[6] NC State Extension. “Nigella Damascena ‘Cramers’ Plum.” 1997 trial information.

[7] Armitage, AM & Laushman, JM. The Production of Annuals, Perennials, Bulbs, and Woody Plants for Fresh and Dried Cut Flowers. Timber Press; REV & Enlarged edition (June 17, 2015).

[8] Floret, LLC. Green Dragon Cress description. “Long, strong stems have a heavy branching habit, producing 6-12 airy stems from a single plant.”

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