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Voices of Horticulture: Dean Kopsell, University of Tennessee

Dean Kopsell greenhouse University Tennessee



Dean Kopsell greenhouse University TennesseeDean Kopsell, University of Tennessee
Eating marigold petals

Dr. Dean Kopsell talks about why we should eat marigold petals and what his students found to be the best red to blue ratio for peak carotenoid concentrations.
Dean is a professor at the University of Tennessee and has studied an eclectic range of crops including Arabidopsis, basil, broccoli, cilantro, kale, lettuce, microgreens, onions, purslane, spinach, squash, turfgrass, and tomatoes.

1. Dean’s UT url:

2. Selected work of Dean Kopsell:

3. Dean’s Social Media:
Dean on Twitter: @UTPhytonut

Dean on LinkedIn:

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Voices of Horticulture: Dr. Gioia Massa, NASA

Gioia Massa NASA lettuce



Gioia Massa and Veggie

Dr. Gioia Massa, “Veggie” Scientist at the Kennedy Space Station, NASA

“NASA’s Veggie and Space Kids”

Dr. Gioia Massa is a plant scientist in NASA’s Veggie program which aims to grow plants in the International Space Station (ISS). Gioia is a Future Farmers of America (FFA) alumni and has grown her early love for plants to a career that is now helping us explore space and preparing humans for space travel. Her professional talks are captivating, inspirational, mind-boggling and always end up giving me goosebumps. She talks with me briefly about NASA’s “Veggie” program on the ISS and how kids on earth are being inspired to reach for the stars.



Gioia on “Ask Me Another” Game Show
NASA Veggie:
Gioia on StarSpot
Gioia on YouTube:


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Voices of Horticulture: Bruce Bugbee, Utah State University



Research-Bruce-Bugbee-2016Dr. Frits Went and the Pursuit of the McCree Curve

Dr. Bruce Bugbee of Utah State University was the opening speaker at the 2016 International Society for Horticulture Science Symposium on Light in Horticulture. Dr. Bugbee talks candidly with me about how understanding history can give us a keen insight into today’s botanical questions about light and the outlook of our future.




For more information on Dr. Bugbee’s program visit these sites:




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CBOP – Hort Americas Closed Bottom Organic Plug

Hort Americas CBOP

Propagating in coco coir is a great way to establish plants. Now with the new Closed Bottom Organic Plug, CBOP, from Hort Americas you can reap the benefits of what you sow.

CBOPs are available in three sizes to fit the specifications of your production system. Whether it is nutrient film technique, raft, grow bag, or directly back into Riococo blocks/slabs, the new CBOP is easy to use and has all the benefits of using Riococo coir.

Currently, we have the 32mm (1.26 in) and 42 mm (1.65 in) size available. The 25 mm (0.98 in) size will be available in 2016.



pH & EC measurements 2:1 water extraction

To see more product information on the Hort Americas Closed Bottom Organic Plug, click here.

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Starting Seeds in Grodan

The most important thing when using Grodan stone wool is that you need to saturate the product fully before using it. When you don’t fully saturate it, some of the stone wool can stay dry and will be hard to get wet at a later stage (hydrophobic). A way to check if the product is fully saturated is to weigh the product and it should be above a certain weight. As an example a Grodan Delta DM6G Grow Block of 10 x 10 x 6.5 cm (4” x 4” x 2.5”) has a volume of 650 ml, so in theory if it is completely filled with water it should weigh 650 grams. However, there will always be air in the Grodan rock wool so we take a water content (WC) of about 85% after initial saturation, meaning the Grow Block should be approximately 550 grams or slightly greater.

I recommend using nutrient solution at 5.5 pH when saturating the product so that nutrients are immediately available for the plant. For the germination itself nutrients are not needed, so some people saturate the plugs with just water and then add the nutrient solution immediately following germination. However, fairly quickly after germination nutrients are needed for further development. So to sure it is easier to saturate the plugs with nutrient solution. Most growers use 1/2 rate nutrient solution for starting then full rate at transplant.

Below are characteristics of some of the most common types of Grodan used in hydroponic production.


Grodan AO cubes 25/40 10/10

AO cubes are recommended for lettuce, herbs, and other greens in a raft system as the tapered base makes it easier to fit into the raft faster.


AO 25/40 mm (0.98 x 1.58 in)
L25 x W25 x H40 mm
200 (20 x 10) cubes per pad
Grodan-ao-cubes6,000 cubes per case
30 pads per case


Top = 25 mm
Bottom = 19 mm
Height = 40 mm
Hole = 10 x 10 mm
Weight dry (1 cube) = 2 g
Weight saturated (1 cube) = 18 g
Also available:  AO 36/40 = 1.5 in; 98 cubes/pad; 2,940 cubes/case
AO 50/40 = 2 in; 50 cubes/pad; 1,500/case


Grodan AX cubes 25/40 10/10

AX cubes are recommended for lettuce, herbs, and other greens in a NFT system as the wider base gives the plug more stability in the gutter.


AX 25/40 mm (0.98 x 1.58 in)
L25 x W25 x H40 mm
200 (20 x 10) cubes per pad
AX-cube6,000 cubes per case
30 pads per case

Top = 19 mm
Bottom = 25 mm
Height = 40 mm
Hole = 8 mm (1/4)
# per pad 200 (20 x 10)
Weight dry = 2 g
Weight saturated = 18 g


Grodan Kiem Plugs in French Trays



Kiem Plugs in French Trays
# per tray = 240 (12 x 20)
Height = 2.1 cm
Dry weight = 1 g
Kiem Plugs
Height = 2.1 cm
Weight dry = 1 g
Weight saturated = 9 g


Grodan Block Delta DM4G


7.5 x 7.5 x 6.4 cm (3 x 3 x 2.5 in)
Weight dry = 25.3 g each
Weight saturated = 273 g each
Volume = 368.7 cubic centimeters
85% WC = 313.4 g


Grodan Block Delta DM6G


10.2 x 10.2 x 6.4 cm (4 x 4 x 2 1/2 in)
hole = 1.5/1.6 in (36/40 mm)
Weight dry = 45.6 g each
Weight saturated = 494 g each
Volume = 655.5 cubic centimeters
85% WC = 557.2 g


Grodan Block Delta DM9G


15 x 10 x 6.5 cm (6 x 4 x 2.5 in)
two holes
Weight dry = 67-73 g
Weight saturated = 879 g
Volume = 975 cubic centimeters
WC 85% = 828.8 g


Grodan Grotop Expert Slab


Grotop Expert
100 x 20 x 7.5 cm (39.4 x 7.9 x 3 in)
(99 x 19 x 7.8 cm)
Weight dry = 753 g


Grodan AX 25/40 cube with lettuce roots and stem post-harvest.
Grodan AX 25/40 cube with lettuce roots and stem post-harvest.

Also available from Hort Americas:

Grodan Block Delta DM9G 27 x35 top right (144/case)

Grodan Block Delta DM6G 20×15 1 hole

Grodan Block Delta DM6G 27×35 2 hole

Grodan Block Delta DM4G 20×15 (384/case)

Grodan Block Delta DM4G 27×35

Grodan Cube AO 36×40 15/15 hole

Grodan Cube AO 36×40 10/10 hole

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Where does phosphorus fertilizer come from?

Phosphorus symbolIf your phosphorus fertilizer is sourced from the U.S. it is probably derived from Hillsborough, Polk, Manatee, and Hardee counties in Florida. Recently, I had the opportunity to tour Mosaic’s South Fort Meade Mine facility. The Mosaic Company’s South Fort Meade Mine has an annual production of 6.5 million tons per year running 24/7/365. It’s size is 28,000 total acres with 15,000 currently active acres with 3 drag lines.

Process Overview: Three Steps

1. Mining – Phosphate matrix is extracted from the ground. Clay and sand are removed. The refined phosphate rock is transported by rail for further processing.

2. Fertilizer production – Mosaic process nutrients in the phosphate rock into a water soluble form suitable for plant uptake

3. Distribution – Finished fertilizer is distributed both domestically and internationally by ship, barge, rail and truck directly to growers.

The massive production draglines are massive excavators (Fig. 1) that actually can move slowly across the mine dragging an oversized bucket. The Production Draglines are manned by just two employees. Each of the draglines weigh 6.9 million pounds and the bucket alone weighs 100,000 lbs (Fig. 2). The mining cut can be up to 320’ (Fig. 3). The overburden (sand & clay) is first removed to uncover the matrix of phosphate rock, sand and clay. The matrix is removed until it reaches hardrock (limestone or dense clay). If you are lucky enough you can discover prehistoric shark teeth or bones from creatures that once ruled the ocean where the mine is today.

Pit cars deliver water hydraulically with 300 psi and 16,000 gym to churn the matrix into a thick slurry that can be pumped back to the plant. At the plant, the washer removes oversized material between 1- 8 inches. Clay is scrubbed and rinsed away where it is moved to the clay reclamation centers. The washer feeds all undersized phosphate and sand smaller that 1mm to the Flotation Plant for separation. A biodegradable soap from pine trees is used to separate the phosphate from the sand. The sand is used to reclaim the mine. Since 1975 all mined land is reclaimed acre for acre (Fig. 4).

The phosphate rock is then loaded and shipped to fertilizer plants all over the US and then it eventually ends up in your hands where you use it grow healthy plants.

Special thanks to Mosaic company and the American Society for Horticulture Science for offering this unique tour.

ASHA logo Mosaic logo


Figure 1. Production Draglines w bucket
Figure 1. Production Draglines w bucket


Figure 2. Dragline bucket
Figure 2. Dragline bucket


Figure 3. Mining cut
Figure 3. Mining cut


Figure 4. Park at reclaimed mine
Figure 4. Park at reclaimed mine



Further reading:

Mosaic, South Fort Meade mine’47.5%22N+81%C2%B045’25.9%22W/


The Fertilizer Institute.