Suggestions for seedling handling

My present procedure is to plant the germinated seed in small 1-3/4 inch square peat pots, 50 of which into a standard 11 inch by 22 inch seed tray. I am able to place 4 of these trays under 2 sets of 2 tube 4 ft shop lights.

When the roots start coming out of the bottom, the peat pot is placed into a round 3 inch diameter (actually 3 1/4) by 4 1/2 inch deep peat pot. The 3 inch peat pots are placed into a clear plastic clothes storage box (39 inches by 16.4 inches by 9.2 inches height) that is convenient to use with two 4 foot florescent shop light fixtures. This size box holds 44 of the three inch peat pots.

I wonder if I would not be better off using one of the 72 compartments plastic inserts for the first step, and transferring with a spoon into whatever I decide to use for the second step. Comments?

I noticed that a 2-1/4 square by 6 inch deep jiffy strip is also available. Does anyone use these?

Please suggest other methods that have worked for you.



I’m new to rose breeding (BTW thanks for the seeds!), but I’m transplanting my germinated seed directly to 3" round peat pots. Saves me a transplanting step and I’ve used this method for a number of years on perennials before I got into roses.

If I have a lot of one variety that I’m not as interested in, I’m sometimes planting more than one seedling per pot with possible thoughts of dividing later (I’m also trying “predividing” the soil in these cases by using a thin board (tongue divider) to split the soil while the plants are small.)

As to lighting I’m not ideal. I’m using flourescents either 1 cool white + 1 warm white OR 1 daylight + 1 cool white (although 1 warm white may be better w/ the daylight)

I have 3 trays crosswise under each 2 tube shoplight (my shelf is too short to hold 4 trays so I have ‘wasted’ lighting on the ends). To decrease the amount of “lost light” I “extend” the reflector by taping aluminum foil to the reflector. The outside edge of the foil then rests on the edges of the seed trays.

Chris Mauchline

I am near the bottom of my case of 3 inch diameter round peat pots so I need to either buy another case or switch to something else.

I have decided to try a case of the new 2-1/4 square by 6 inch deep jiffy strips (somebody has to be first).

I have ordered them from Mellinger’s ( item #523 at ).

They are supposed to be used in the following inset:

But I could not find anyone who sold it.

I probably will just try them in a standard tray that I will modify as follows. I have a number of old clear plastic domes that have yellowed badly. I will cut out the top and tape the rest to a standard tray. This should keep the jiffy strips from drying out as fast as they would without the sides extension. I may also pack “water crystals” around the outside space between each pot.



(From the picture) they narrow down to such a small “point” that I think the total volume will not be that much greater than a shorter jiffy strip of a similar dimension. I think they will tend to dry out easily (large surface area to volume). Anyway good luck with them, and let us know how they turn out!

Chris Mauchline

Hi Henry and Chris!

I’ve been transplanting seedlings into those 72 cell inserts (actually 12 break apart 6-packs per flat). I wait until the seedlings are a few inches high in the cells and then decide which ones have enough vigor and seem worth keeping at that point(usually about half). This is usually before the flowers start to open if they are repeat flowering. I then use those 3" square deep press fit pots (32 per flat) to transplant them into. The seedlings usually start flowering in those pots and may be trimmed back if they get too large before they are hardened off and planted outside. If it is a rose I am especially found of I may transplant it one more time before spring if it can use it. I used to use round Styrofoam pots, but like the square ones because I can fit more in a flat and the soil volume is about the same as an 8 ounce cup. I reuse the square pots year to year. I also sometimes reuse the 6 packs too one extra time, if for nothing else marigolds. About every other year I buy another case of the 6-packs. I’m thankful for the opportunity to buy from a local wholesale greenhouse supplier which sure saves a lot for soil and pot costs.


David, could you supply more detail (maybe a link?) re. the pots and flats you use? How deep are they? I have to ask that because if they’re too deep I wouldn’t be able to fit them under the lights in my homebuilt light stand.


Hi Peter!

I think they are the 2.5" square (2.5" sides, ~3" diagonal). Thirty two fit per flat (four by eight pots in a flat). They make nice trays that the pots nest securely in, but I have just put them in an open flat.

Here is one link describing them:


Chris, yes I agree with you that: “I think they will tend to dry out easily (large surface area to volume).”

Still, someone must like them since they introduced them. Since I could not locate a supplier of their “holders” (which did not look so good anyway), my latest thought is to try making my own holders by forming a “mold” using a can of expandable urethane foam (I would cover the peat strip with syran wrap). I plan on leaving the bottom exposed so that excess water can drain out. I assume that these foam holders would be reusuable. I envision a result similar to the Styrofoam holders that Park’s Seed sells.