A hot-box for germinating seeds and rooting cuttings

Today's project was to load the hot-box I set up to germinate seeds, heal grafts and to callous cuttings and speed rooting.

Mrs ERJ is slightly exasperated because every spring I fill up our master-bathroom (the warmest room in the house) with horticultural projects. I cheerfully bowed to her wishes and spent a little bit of money to fabricate a substitute. 

The pieces-parts I needed showed up yesterday.

I already have several of these.

The only problem with this unit is that the bottom is EXACTLY the size of the multi-cell insert and is too small for the tray that goes beneath it.

The obvious solution, obvious after I had it all buttoned up, was to turn the unit on its side so can take advantage of the taper. The bottom (now the wall that is farthest way) will still crush the tray but I will be able to get my fingers behind it and pull it out when I need to.

20 Watt heating mat on the bottom. A couple of weights to hold it down. A board across the top to hold the Inkbird sensor.

I wanted to make sure that 20 Watts would be enough heat to reach 80F in the 55F basement. That is why I kludged together and made a test run. The back-up plan was to put two, 20 Watt heating mats into the bottom of the cooler hot-box.

80F is 27C. 26.9C is plenty good enough.

80F or 27C seems to be right in the sweet-spot for rapid germination of warm-season crop seeds like tomatoes and peppers. It is also great for generating callous tissue between bench-grafts of grapes and nuts. Most fruit species can callous at much lower temperatures. Callous tissue is also the undifferentiated tissue (similar to stem-cells in mammals) that can morph into roots.

Incidentally, 80F is MUCH warmer than what we keep the master bathroom. Much warmer! So I will be getting more of what I want AND make Mrs ERJ happy. Win-win. 

Here is the box with a 50 cell seeding tray in it.

• 20  Crack Willow (Salix x fragilis) on the left
• 5 cells of a (S. purpurea x S. miyabeana) hybrid. I put two cuttings per cell because the cuttings are small
• 10 White Willow (Salix alba)
• 5 Red Twig Corkscrew willow (Salix matsudana 'Tortuosa',)
• 5 (S. viminalis x  S. miyabeana) hybrid
• 5 Yellow Twig Corkscrew willow