Diatomaceous Earth as a seed starting medium

[RayR]

Excellent Baizanator! Tell us about your materials and methods. What are you using for the peat and the coir mixes? What will you be using for nutrients?

[Baizanator]

Originally Posted by RayR

Excellent Baizanator! Tell us about your materials and methods. What are you using for the peat and the coir mixes? What will you be using for nutrients?

The mixes being used are:

Peat-Based: Johnny's 512 Mix
Coco Noir - Hydrofarm JSCCM25 Organic CoCo Mix

The cultivars being used are:

A. First Prize VFFNT Hybrid
B. Florida 91 VFF Hybrid
C. Halley 3155 VFF Hybrid
D. Mountain Gold VFF
E. Mountain Spring VFF Hybrid

As you can see in the photo, there is one flat for each cultivar. In that flat there are ten of each variety in each medium. There was only one seed planted per slot to accurately calculate the germination rate.

Fertilizer will be added at a later date. It is Park's Success Plant Food, a 20-20-20 seedling fertilizer that is water-soluble at the 1/4 tsp/gallon rate.

Upon completion (I haven't decided how long to go) plants will be pulled, washed and weighed. I know there are lots of holes in this but the professor just wants to see if we can conduct and design a true experiment. If I were pursuing this for thesis research I would obviously replicate multiple times with much more in the way of plant numbers.


My true worry is that the Diatomaceous earth was EXTREMELY hard to find and what we got is a pool filter medium that is VERY fine. I just hope the little roots can grow through it.

[RayR]

I think you are going to have a problem with pool filter DE aside from the fact that it has high levels of fine crystalline silica particles and is dangerous to work with.
The fine powder is like food grade DE and is not ideal at all for horticulture. There will be much cohesion between the particles in water and it will choke off oxygen from the roots. It's like trying to grow in very fine clay.
You really need a coarser aggregate. You can't even find Moltan Ultrasorb or Optisorb at the local auto parts stores?

[Baizanator]

Originally Posted by RayR

I think you are going to have a problem with pool filter DE aside from the fact that it has high levels of fine crystalline silica particles and is dangerous to work with.
The fine powder is like food grade DE and is not ideal at all for horticulture. There will be much cohesion between the particles in water and it will choke off oxygen from the roots. It's like trying to grow in very fine clay.
You really need a coarser aggregate. You can't even find Moltan Ultrasorb or Optisorb at the local auto parts stores?

Just bought some Optisorb from Amazon. It was pretty cheap. I just hope it gets here in time.

[RayR]

You'll be far better off in making a fair and successful study.

There are other problems with pool grade DE:

It is flux calcined. The DE is mixed with Sodium carbonate (Soda Ash) which is a strong base and is heated at high temperatures. This alters the pore structure as well as changes the amorphous silica to crystalline silica.It's OK for water filtration, but not much good for anything else.

PH Is another factor that is important. I don't know what the PH of pool grade DE is but seed starting mediums are PH balanced between 6.5-7.0. So if you're going to use an inorganic medium to compare it too you want it in that same PH range that is optimal for seedling germination and growth.

Another important factor is whether the DE is from a fresh water deposit or a saltwater deposit. You only want DE that you know comes from a fresh water deposit for horticultural use. Salt water DE obviously has a high concentration of Sodium and that ain't good for plants. Where that pool grade stuff comes from—who knows?

[nativeplanter]

For the purposes of your class, it sounds from your description that this will be a fair and successful study - of this particular pool filter DE as a medium. It just won't yield the answer to the question you would have preferred to ask - if a coarser DE would work nicely. But it's still a good experimental setup that you can repeat later with different material.

I assume this is for a stats class in experimental design? What school are you taking it at? The only think I think I might change is that the locations of the cells could be randomized on the bench. That would help account for variables that might be caused by edge effect, such as watering differences, air movement and humidity, and shading.

Other dependent variables you could measure might be separate root and shoot dry weights, specific root area, and leaf area.

Even if it doesn't arrive in time, I bet the greenhouse staff would let you set up another experiment using the Optisorb. They would probably find the results just as interesting as you will! I think you have a nice experiment going.

[Baizanator]

Originally Posted by nativeplanter

For the purposes of your class, it sounds from your description that this will be a fair and successful study - of this particular pool filter DE as a medium. It just won't yield the answer to the question you would have preferred to ask - if a coarser DE would work nicely. But it's still a good experimental setup that you can repeat later with different material.

I assume this is for an stats class in experimental design? What school are you taking it at? The only think I think I might change is that the locations of the cells could be randomized on the bench. That would help account for variables that might be caused by edge effect, such as watering differences, air movement and humidity, and shading.

Other dependent variables you could measure might be separate root and shoot dry weights, specific root area, and leaf area.

Even if it doesn't arrive in time, I bet the greenhouse staff would let you set up another experiment using the Optisorb. They would probably find the results just as interesting as you will! I think you have a nice experiment going.

The class is a basic research methods course. I got my M.Ed. in August but I'm still working on my M.S. Agronomy. The institution is Tarleton State University in Stephenville, Texas.

[Baizanator]

Originally Posted by nativeplanter

For the purposes of your class, it sounds from your description that this will be a fair and successful study - of this particular pool filter DE as a medium. It just won't yield the answer to the question you would have preferred to ask - if a coarser DE would work nicely. But it's still a good experimental setup that you can repeat later with different material.

I assume this is for a stats class in experimental design? What school are you taking it at? The only think I think I might change is that the locations of the cells could be randomized on the bench. That would help account for variables that might be caused by edge effect, such as watering differences, air movement and humidity, and shading.

Other dependent variables you could measure might be separate root and shoot dry weights, specific root area, and leaf area.

Even if it doesn't arrive in time, I bet the greenhouse staff would let you set up another experiment using the Optisorb. They would probably find the results just as interesting as you will! I think you have a nice experiment going.

Went to Autozone and looked again. Found ONE bag of Optisorb on the bottom shelf in the corner. Stoked that I could find it.

[b54red]

I just transplanted some rutabaga seedlings that I started in the bottom of egg cartons. They were a little harder to transplant than regular seed starting mix but not that difficult as long as the Ultrasorb is moist. Now I just have to wait and see how they do if the squirrels leave them alone long enough for them to grow. I will be trying to transplant some lettuce seedlings in a week or so that were also started in Ultrasorb.

[greentiger87]

Just wanted to let you guys know that Utrasorb has worked *great* for me so far, for the following:

1) Bareroot strawberries, after I screened out the really fine material. I was skeptical, but it's working great so far, significantly better than my bark based mix. It's about on par with another mix I use, a "gritty mix" with large well screened pieces of bark, granite, and turface.

2) Very hard seeds of Caesalpinia pulcherimma (Pride of Barbados), after standard scarification/soaking. The bonus here will be how easily it will be to transplant, considering that the diatomite falls off the roots with no problem. It also seems to be helping with the excessive taproot this plant likes to grow, which is a major problem for containerized growth from seed.

3) Cuttings of some hybrid tomato varieties. Even with no humidity dome or tent, these cuttings had no problems growing a superbly fibrous root system.

4) Cuttings of beautyberry, Callicarpa americana. This species does root easily, but I did this with no rooting hormone, just seaweed and subpar cuttings. One week in a humidity dome, and all but one of the cuttings struck. I haven't inspected root systems yet, but I'm optimistic.

Next up, nasturtium and calendula. I've had terrible germination rates with nasturtium in seed starting mix, so I'm excited to see if it makes a difference.

Edit: I'm using Ultrasorb made by Moltan, NOT optisorb

[Rockporter]

I am about ready to start transplanting my seedlings of chard and lettuce seeds, my spinach did not come up at all, not one.

I would like to make my own transplant mix and have on hand, canadian peat, vermiculite and perlite. I cannot find any composted bark fines in my area, would it be ok to just use the items I have on hand? I also picked up nutrients to add to the mix.

Do I take the seedlings and separate each one into their own container? Or do I just replant them all into a larger container and separate when actually planting in the garden?

[RayR]

Originally Posted by Rockporter

I am about ready to start transplanting my seedlings of chard and lettuce seeds, my spinach did not come up at all, not one.

I would like to make my own transplant mix and have on hand, canadian peat, vermiculite and perlite. I cannot find any composted bark fines in my area, would it be ok to just use the items I have on hand? I also picked up nutrients to add to the mix.

Do I take the seedlings and separate each one into their own container? Or do I just replant them all into a larger container and separate when actually planting in the garden?

I see folks down South are experimenting with all kinds of things.

Rockporter, my Spinach did nothing too, I think my seed is too old.
I never grow Chard transplants usually, I direct seed that in mid to late spring in the garden beds. No need for a fall crop, they keep on going until heavy frost.

I typically start lettuce indoors in April for the summer crop, planting the seeds dense 1/8"apart on top of the medium in nursery 6-packs but you can start them in anything you've got. After they have 4 true leaves I separate them taking the healthiest seedlings and pot them up in individual cells to grow up until it's time to transplant them in the garden or in large containers to grow out full heads for picking in June and early July.
For the fall, I'm not so organized, I like to start new seedlings in late August preferably but like this year I was a couple weeks late. I skip the potting up stage and plant the little guys right in whatever big containers I have unused.
Since I grow a seed crop every year, I also have volunteers popping up all over the place in the garden and the yard. The fall harvest here usually doesn't make any big mature heads because of the shorter days and the temps get too cool for rapid growth.
You folks in the South have a whole different timetable for growing cool weather crops like lettuce.

[greentiger87]

I usually direct sow lettuce and chard seed as well, at the beginning of October. I'm late on the lettuce this year, but given our hot temps this week that was probably a blessing in disguise. Sorry your spinach didn't come up.. it does seem to have less germination than some other leaf veggies, but I scatter sow those as well, so i don't notice it as much.

By "transplant mix", do you mean something to grow them in until you put in the ground? If so.. why not just put them in the ground now? Are you worried it's still too hot? I could see that being a problem for the lettuce, maybe.. but the chard should be fine. The sooner you get them in the ground, the sooner you can start enjoying your crop.

As far as individual pots for transplants vs large pots with multiple seedlings, it's really a personal choice that varies with your specific conditions. If you intend to delay planting them in the ground for a while, individual pots are best to avoid entangled root system. These are already pretty shallow rooted plants that don't like root disturbance, so I'd go for individual pots regardless. But once you get a feel for the mix you're using and the age you want to transplant at, you may find that separating the root systems is no big deal and that a big pot is more convenient for you.

Your proposed mix of peat, vermiculite, and perlite is fine as long as it is very short term. The vermiculite in particular will dissolve into a soupy mess quite quickly. Jiffy seed starting mix is in fact a 50:50 mix of vermiculite and peat fines. Remember to use lime though, to raise the pH to an acceptable level. 1-2 tbsp per gallon of mix is a very rough estimate. Also remember that this mix is very poor in nutrients - fine for seed starting, not so much for growing young plants, unless you supplement with water soluble fertilizer.

[Rockporter]

Originally Posted by RayR

I see folks down South are experimenting with all kinds of things.

Rockporter, my Spinach did nothing too, I think my seed is too old.
I never grow Chard transplants usually, I direct seed that in mid to late spring in the garden beds. No need for a fall crop, they keep on going until heavy frost.

I typically start lettuce indoors in April for the summer crop, planting the seeds dense 1/8"apart on top of the medium in nursery 6-packs but you can start them in anything you've got. After they have 4 true leaves I separate them taking the healthiest seedlings and pot them up in individual cells to grow up until it's time to transplant them in the garden or in large containers to grow out full heads for picking in June and early July.
For the fall, I'm not so organized, I like to start new seedlings in late August preferably but like this year I was a couple weeks late. I skip the potting up stage and plant the little guys right in whatever big containers I have unused.
Since I grow a seed crop every year, I also have volunteers popping up all over the place in the garden and the yard. The fall harvest here usually doesn't make any big mature heads because of the shorter days and the temps get too cool for rapid growth.
You folks in the South have a whole different timetable for growing cool weather crops like lettuce.

Lettuce will bolt really fast if planted too soon here as well as chard or any leafy green. I am bummed my spinach didn't take because there isn't any at the local stores to purchase and my seed was new seed, I just think I got bad seed or it just wasn't the right setup for it.

[Rockporter]

[QUOTE=greentiger87;306333]I usually direct sow lettuce and chard seed as well, at the beginning of October. I'm late on the lettuce this year, but given our hot temps this week that was probably a blessing in disguise. Sorry your spinach didn't come up.. it does seem to have less germination than some other leaf veggies, but I scatter sow those as well, so i don't notice it as much.

By "transplant mix", do you mean something to grow them in until you put in the ground? If so.. why not just put them in the ground now? Are you worried it's still too hot? I could see that being a problem for the lettuce, maybe.. but the chard should be fine. The sooner you get them in the ground, the sooner you can start enjoying your crop.

As far as individual pots for transplants vs large pots with multiple seedlings, it's really a personal choice that varies with your specific conditions. If you intend to delay planting them in the ground for a while, individual pots are best to avoid entangled root system. These are already pretty shallow rooted plants that don't like root disturbance, so I'd go for individual pots regardless. But once you get a feel for the mix you're using and the age you want to transplant at, you may find that separating the root systems is no big deal and that a big pot is more convenient for you.

Your proposed mix of peat, vermiculite, and perlite is fine as long as it is very short term. The vermiculite in particular will dissolve into a soupy mess quite quickly. Jiffy seed starting mix is in fact a 50:50 mix of vermiculite and peat fines. Remember to use lime though, to raise the pH to an acceptable level. 1-2 tbsp per gallon of mix is a very rough estimate. Also remember that this mix is very poor in nutrients - fine for seed starting, not so much for growing young plants, unless you supplement with water soluble fertilizer.[/QUOTE]


I will plant the chard and lettuce at the community garden and it has been too hot for that. I found some red sails lettuce and some romaine that is ready to plant at the local nursery so I can at least start that. I can plant the seedlings I am growing after these plantings are done giving lettuce to me.

Thanks, for the hints on the lime, I will use that for sure and I have some ferts I bought the other day to use in the mix.