Soil seedlings vs. Rocks seedlings - a study of the differences

March 15, 2009 - Day 1

Containers are prepared as follows;
    2 containers will have rock base (fish gravel)
    2 containers will have soil base (peat, vermiculite, perlite)
    40 seeds of the same cross divided as 10 seeds per container

The rocks - purchased from Wal-Mart as fish gravel.  I had some left over from last year that I had boiled and appear to be natural stones.  Brand is "Stoney River".  Last weekend I also purchased a new supply and that was the same brand now offered by our local Wal-Mart.  When my left over supply (left side of photo) was compared with my latest purchase (right side of photo) I can see that the newer rocks had a glossy coating.  This must be the polymer coating that should not be boiled.  I rinsed the new stones with scalding water from a boiled kettle regardless.

The soil - not actually soil at all but a mix of peat, vermiculite and perlite.  This was damped with distilled water, same water to be used for the rocks seedlings just to keep everything else identical.

The seeds - As luck would have it I won an auction of 40 seeds from Linda Michaels.  This was the perfect number of seeds that I was hoping to have for this experiment.  It was a cross of a seedling that she has since registered as 'Day Triffid' as pod parent with pollen from Reinke's 'Black Passion'.  The seed baggie still has the seedling ID on it.

The containers - I am able to get these containers from a local grocery store that uses them to sell fruit cups from their deli section.  I like the fact that they are fully sealed and they have the domed cover.  I have used McDonald's ice coffee cups as well because the flat top makes them easy to stack but the straw hole does let more moisture escape than the fully sealed dome's do.  The supplier of the domed container is a US company and a website link can be provided on request.

So, now we put all the parts together...

I had originally set them under the lights immediately after filming, but lighting is not required for seed germination.  It is heat that I need for condensation.  I realized that they would be better served at this time on my window shelves.  The shelves are lined with black peel-n-stick floor tiles to attract the sun.   Ignore the thermometer - it was warmed by the sun just a few minutes earlier.  Actual temperature is 5°C or about 37°F and still about 30" of snow on the garden.

Daylily seeds don't need light to germinate but some sun to warm the containers and create condensation (humidity) is desired.  I don't think the T5 bulbs would produce the same degree of heat that they would get from the sun.  Once the seeds have germinated I will move them under the light.  In just 75 minutes on what's become an overcast day the containers are showing signs of condensation activity.

March 16, 2009 - Group 1, DTBP Day 2

Below are the DTBP (Day Triffid X Black Passion) containers on the second day showing the condensation buildup after a day of sunshine.  If you'll notice, I have black floor tile (peel & stick) on my window shelves that attracts the sun and transfers heat to to soil and rocks.  The heat is maintained long after the sun has gone down and the condensation does not start to clear until sometime between midnight and 7am.

March 22, 2009 - Group 1, DTBP Day 7

A big jump in time but there was nothing (absolutely nothing) to report.  The seeds have not germinated yet in any of the containers.  I must have picked a group of dormant seeds - hopefully not too dormant or this could be like watching grass grow - actually, I can't go a week without mowing in the summer so grass grows quicker.  :(

All containers are showing no signs of life.  Here are close ups - one of the soil cups and one of the rocks cups.

I have taken the opportunity to show how the condensation has cleared in the am and then re-establishes as the day warms up.  Position of the containers is rotated every day or two.

March 22, 2009 - Group 2, IGIC/BIC Day 1

I have decided to run a second group of seeds through the same experiment.  I made some errors in the first group that I would like to remedy.  I forgot to do my diluted bleach bath with the seeds.  In addition to that my inexperience with a soil medium left me a little naive.  I thought that medium from a new bag was clean and was surprised to learn that it should be heated to kill anything that may be in it.  I have not been too happy with the time its taking for the Group 1 seeds so this time I selected seeds that were a little fuller in their seed coats hoping for a quicker germination time.

The seeds are 20 seeds IGIC (Indian Giver X Ice Carnival) and 20 seeds BIC (Bagana X Ice Carnival) split as 10 seeds per container.

The soil premixed medium (peat, perlite and vermiculite) was microwaved on high for 1 minute and was steaming when ready.  The medium was dampened with distilled water.  A seed bath was prepared from a 10% bleach solution.  Containers were thoroughly washed with antibacterial soap and rinsed in a 10% bleach solution.  There was no special treatment done to the rocks.


March 27, 2009 - Group 2, IGIC/BIC Day 5

In the IGIC rocks container we have our first sprout. These were the seeds that looked the most likely to sprout at the onset.  They were full in their seed case so the quick germination is not a surprise.  At this point I am unable to say if the comparable soil group has done the same - it probably has.   There are actually 3 seeds with their radical poking out.  One is dead center while another is up against the label knife and the third is the leftmost seed.

March 27, 2009 - Group 1, DTBP Day 12

Group 1 is boring the heck out of me.  There's nothing going on at all.  Well, unless you count algae growth as something.  This is the group where I neglected to microwave the soil medium so it appears that there was something in the soil to cause the algae?  The water was distilled water only so I am assuming the soil plus humidity caused the algae growth.  I have been adding small amounts of distilled water periodically to maintain the moisture.  During the day the containers expand and you can hear them sizzle as air and humidity escape.  I have also alternated the windows between Group 1 and Group 2.  Group 1 spent the first 12 days in an east-facing window while Group 2 spent their first 5 days in a south-facing window.  Currently Group 2 is east-facing and Group 1 is south-facing.

March 29, 2009 - Group 1, DTBP Day 14

Finally!  "Houston, we have lift-off."  Germination has begun.  Now that there are differences between the 4 containers of Group 1, I have identified them with a different colour for each similar label marker.  The soil cups are 'purple' and 'orange' while the rocks cups are 'blue' and 'green'.   In the photo below you can see the colour codes.  In addition I have indicated two areas with red arrows.  Close ups of those areas follow this photo.

This photo close up of DTBP container 'green' shows a seed with some kind of mould growing on it.  I don't mess around with mouldy seeds and it was removed immediately bringing the number of seeds down to nine in this container.

In the next photo you can see the close up of the first sprout in the DTBP group in container 'purple'.  From the group shot it is hard to identify it because there is green (algae?) growth on the perlite as well so I zoomed in.

March 29, 2009 - Group 2, IGIC Day 7

Well, there's good news here too! The soil container is showing germination of two seeds and the stage of germination exceeds that of the rocks containers.  There are green fans above the soil line whereas the rocks containers are not showing any signs of green yet.

March 29, 2009 - Group 2, BIC Day 7

And some news in the BIC containers .  First germinated seed visible in the rocks container is to the left of the label marker up against the outside edge of the container.   Currently the soil containers have the lead on the germination times so I suspect I have equal or greater germination happening in the soil containers as well - just can't see it yet.

March 30, 2009 - Group 1, DTBP Day 15

Still no action in the rocks containers but both soil containers are showing germination of 2 seeds each.  Any green sections without an arrow is just some kind of algae growing on the perlite I think, because the soil was not sterilized.

March 30, 2009 - Group 2, IGIC/BIC Day 8

Soil takes the lead again.  The germinated seeds are far more advanced in soil containers than they are in the rocks containers.  Two shots - one looking down and a second shot from the side.  The cups are in the same order in both photos.

March 31, 2009 - Group 1, DTBP Day 16

Seed germination count.  So far the soil containers are showing 2 each whereas the rocks have nothing going on.  If you'll remember, I had to remove a seed from the 'green' container so the count is out of 9 rather than 10.

March 31, 2009 - Group 2, IGIC/BIC Day 9

Here are the second group of seeds showing greater germination even though the time period is shorter.  It would appear that the BIC rocks cup is in the lead with 8 of 10 seeds germinated but it is unfair to make that judgement without being able to see what is happening below soil level in the other BIC cup.

April 1, 2009 - Group 2, IGIC/BIC Day 10

No change in Group 1 today so we'll just look at Group 2 - growing like gang busters!


April 4, 2009 - Group 1, DTBP Day 20

Wow, 20 days and a total of 5 germinated seeds out of 39 (40 less 1 'green' cup seed) in this cross.  ALL of the germinated seeds are in the soil cups.  Still no activity in the rocks containers.

April 4, 2009 - Group 2, IGIC Day 13

I added the side shot to this grouping.  I think its the side shot that tells the story.  The difference is clear.  The soil seedlings are 2-3" tall already while only 2 of the rocks germinations are tall enough have broken soil cover.

April 4, 2009 - Group 2, BIC Day 13

Again, the side shot that tells the story.  The soil seedlings are 1-3" tall already while maybe 5 of the rocks germinations are tall enough have broken soil cover.


April 6, 2009 - Group 1, Day 22 / Group 2, Day 15

Fertilizer for Group 2 (not yet required for Group 1).  During the video I questioned myself on whether or not I had given the third container a second 1mil shot of fertilizer.  In reviewing the video I found that I had indeed missed it.  I added the second shot to the third container. 

Another note - adding 2mil of liquid to the rocks containers brought the level of fluid up over some of the crowns.  I could not siphon off any excess without distorting the amount of fertilizer per container.  What I decided to do was leave the covers off overnight and allow condensation to escape.  By early morning on April 7th the levels were perfect and I replaced the covers.

April 8, 2009 - Group 1, Day 24

April 8, 2009 - Group 2, Day 17

April 9, 2009 - Group 2, Dawn breaks on Day 18

April 9, 2009 - Group 2, IGIC on the evening of Day 18

April 9, 2009 - Group 2, BIC on the evening of Day 18

April 9, 2009 - Group 1, DTBP Day 25

Finally -  I have germination in the rocks cups!  There are 2 seeds in the 'green' container and one in the 'blue'.  I was beginning to lose faith so I was delighted to see them.

April 16, 2009 - Group 1, DTBP Day 32

Things are moving along slowly.  All containers in Group 1 continue to add seedlings.  Personally, I am very surprised by the difference in the germination times between the two mediums.  Soil is still ahead of the rocks.  I'm wondering how much heat retention may be a factor.  I suspect that the seeds tucked into the soil stay warmer overnight whereas the rocks seeds, because of their exposure, would cool significantly faster in the evening.  Don't forget, it is still going below freezing, or very close to it, overnight and they are only one double-pane of glass away from that cold.

April 16, 2009 - Group 2, IGIC/BIC Day 25

I think germination has ceased in Group 2.  There have been no additional seedlings for the last week and there are only 5 seeds of 40 total that have not germinated.  Having said that, there are seeds in Group 1 that are only beginning to germinated after 30 days so I won't count them out yet.  There's no harm in leaving them where they are anyway.

April 19, 2009 - Group 1, DTBP Day 35

Week 5 has ended. No increase in the soil containers but the rocks containers added 3 germinations in the last 3 days.

April 19, 2009 - Group 2, IGIC/BIC Day 28

Week 4 is over for the second group.  I'm not happy to see signs of stress in Group 2.  It is not specific to either grow medium or particular cross.  Stress is most pronounced in the BIC(rocks) container and second most in the IGIC(soil) container.  I think it may be heat-related.  We had a couple of warm sunny days and some of the damage appears to be scorch-like and affected those parts of the leaves that were in direct contact with the dome lid on the containers.

In the split shot below the IGIC(soil) is on the left and BIC(rocks) is on the right.  Both show contact scorch on the upper leaves yet the non-contact lower leaves (bottom shots) also show stress.  While it is true that these primary leaves often are the first 'to go' I think the process has been accelerated by a possible heat build up in the containers.  I can provide more photos on request.

Time to leave the uncontrolled environment of the windows and go under the lights. These are T5 lights running from 8am to midnight daily.

May 10, 2009 - Group 1, DTBP Day 56

Week 8 has ended. Take a close look at the 'blue' container (lower left).  Yes, that is a new germination.  One of the advantages of the rocks containers is the ability to remove the advanced seedlings for transplant and leaving the more stubborn (dormant) seeds behind.  A gentle shake and lift will loosen the seedlings from the rocks leaving any younger sibs behind reasonably undisturbed.  Ordinarily that is what I would be doing at this stage but for the purposes of the experiment I must keep the group together.

As seen in group 2, this would be the time for fertilizer.  However, the group 2 rocks seedlings are not faring very well.   I had originally attributed it to heat stress, and that may have played a roll, but I also think fertilizer burn may have been a factor.  I don't normally add fertilizer to the rocks seedlings until after they have been pulled and transplanted.  For that reason I may not have been correct in my dosage suitable for plants without benefit of soil.  I decided to forgo the fertilizer for this group and it appears to have been the right decision.


May 10, 2009 - Group 2, IGIC/BIC Day 49

Week 7 is over for the second group.  The signs of stress in Group 2 continue despite being removed from the heat of the window sill.  Much more pronounced in the rocks containers.  I think the damage in the soil containers may be heat-related.  We had a couple of warm sunny days and some of the damage appears to be scorch-like and affected those parts of the leaves that were in direct contact with the dome lid on the containers.  However, I think there's also a compound effect of the rocks containers regarding a possible fertilizer burn.  As stated earlier, I am not confident that my dosage was weak enough for seedlings growing without benefit of soil for dispersion.


May 10, 2009 - Soil versus Rocks

Here are the soil group at 49-56 days with burn damage trimmed


Here are the rocks group at 49-56 days with burn damage trimmed.  I think its clear at this stage that the soil seedlings look much healthier even though they were affected by some sun burn.  I'm still thinking that the fertilizer was a benefit to the soil seedlings and a detriment to the rocks seedlings but maybe I'm looking for excuses for a disappointing outcome.


June 8, 2009 - Soil versus Rocks

The whole gang on transplant day. Finally got some sunshine and some warmer temps after a lot of very cool wet weather. The seedlings have spent a significant amount of time in a very small space. Group 1 was started on March 15th and Group 2 a week later on March 22nd.  About 83 days for Group 1 and 76 days for Group 2.  The soil seedlings are ahead, in part, because I was afraid to give the rock seedlings fertilizer.  I need to find a way to do that safely if I intend to stretch these seedlings for 3 months.  Regardless of the fertilizer issue, I honestly believe that the soil group currently has better growing conditions simply because of being in soil.  Expecting a seedling to thrive in nothing but water and rocks for almost 3 months is a little crazy.   Even getting 10 seedlings to thrive in a soil pack of about 2 inches deep by about 3 inches across is pretty incredible.


Here are Group 1 (DTBP) at 83 days.


Here are Group 2 (BIC/IGIC) at 76 days.


Here is the June 8, 2009 video footage of Group 1 (DTBP) at 83 days.

Here is the June 8, 2009 video footage of IGIC (part of Group 2) at 76 days. My camera battery ran out before I could film both BIC and IGIC but the results were similar.

June 9, 2009 - Day after transplant


June 28, 2009 - Soil versus Rocks

Almost 3 weeks since transplant. Although, once labelled the rocks seedlings become easier to identify, I had trouble putting the labels to the pots. The gap in vigour is quickly closing.  This is my outdoor soil mix which includes compost.  All chemical fertilization has stopped other than my own blend of compost tea which all seedlings receive in equal value.


Group 1 (DTBP) rocks in the top 2 pots and soil in the bottom pots.   The background was very distracting so I blended it out.


Group 2 (BIC/IGIC) rocks in the top 2 pots and soil in the bottom pots.


July 4, 2009 - Soil versus Rocks

Last entry. 

There is almost no discernable difference between the rocks and the soil seedlings at this stage despite a significant difference at the time of planting.  The rocks seedlings have bounced back very well.  Just a point of reference - the seedlings you can see in the lower right hand corner of this photo are early March rocks seedlings that were transferred into beer cups in early April.  If you scroll back up to April 19 you will see them under the lights.  They had the advantage of better light and considerably more wiggle room than the test seedlings.

Inventory taken in October of 2009 as follows;

Group 1 - DTBP - green (rocks) 4 of 9 / blue (rocks) 5 of 10 / purple (soil) 4 of 10 / orange (soil) 7 of 10

Group 2 - BIC (rocks) 10 of 10 / BIC (soil) 8 of 10 / IGIC (rocks) 8 of 10 / IGIC (soil) 9 of 10

Every seed that germinated survived.  Soil germination rate of 70% and rocks germination rate of 69.2% 



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