What potting mix do you use for seedlings?

Wondering what potting mix you prefer for seedlings once seeds have germinated in the fridge or before they have germinated.

Also - how often do you water?

Thank you

Mix: equal parts Fafard 3b and perlite.

How often water: every two days.

Perhaps, we would all do anyone reading this thread a favor by including what conditions we’re raising our seedlings in? Mine are germinating in about three quarters day full sun with copious wind here in the Los Angeles area. If I tried to use anything more shallow than the 8" deep tables I have, I would need to not only water them daily, but worry about the sun over heating the roots.

I use straight Miracle Grow Moisture Control Potting Soil because it holds the water well and doesn’t harden. The seedlings are popping up like grass and don’t dry out between waterings. The tables are two by four feet, on sawhorses at about waist height. The bottom of the wooden tables have half inch hardware cloth lined with window screen so drainage is wonderful. There is some run off from the roof eaves when it rains, to there is also wadded up screen held in place with boards and a few stones to diffuse the energy of the more concentrated falling water. Not ideal, but it works. Now, if I added I use that soil, and anyone germinating them indoors tried it, they’d all rot.

I stratified in the fridge with some moist peat for about 60 days. I got a couple of Gymnocarpa germinating so I planted the rest of the seed 1/4 inch deep and covered with a little perlite in pots that are 2 1/2 inches deep. I’m using a 50/50 mix of peat and perlite. They are in my garage that I maintain at about 63 degrees F. Hope this works.

I have approximately 350 OP seeds in the garage and about the same in a simple hoophouse. I’m using the same potting mix in the hoophouse. I’m trying to see what works better.

If and when I get some germinations, the seedlings will get transferred to 2 1/2 x 3 inch deep pots with a light (meaning good drainage) mix of potting soil and Hemlock bark. I get good drainage with this potting mix. Guess I’ll see what happens.

Sunshine Mix #1, as base in 8" deep greenhouse seedling benches, with Sunshine Mix #3 on top, about 3/4", then covered with about 1/2" perlite. The seeds are sown in the Sunshine Mix #3 top dressing.

Jim Sproul

Jim, you may want to think about cutting back on the fertilizer! Your children are getting big, fast!

You didn’t mention having a line of striped progeny going, Jim

Indoor under lights I use Miracle Grow Organic Choice potting soil mixed 2:3 with horticultural grade perlite. I steam sterilize both before mixing (to prevent mites), and screen the potting soil to < 1/4" to make it easier to split the soil with a blade for inserting seedlings. I use 3-oz plastic cups for pots, poking six holes in each with a soldering iron for drainage.

The small cup size maximizes space but imposes a need to be vigilant about watering. In bone-dry air at 65 degrees F I find I have to water every third day, three tablespoons of water per cup. By March the seedlings are big enough to transpire more water so for the last few weeks before moving up to bigger cups outdoors I have to keep a close eye on them. I’m experimenting with clear plastic bags as a sort of terrarium to cut down on the burden and the risk.

Outdoors, in pots, I use a mix of cedar bark mulch, sphagnum moss and fine perlite. I buy the perlite as attic insulation in large bags, which is far less costly than the horticultural grade.

What handsome little fellows, are they your helpers? And my goodness look at all those rose seedlings…marvelous, I would be in heaven.

I usually use a moist paper towel in the frig to keep my seeds in for a few months then I put them in moist play sand that you can get at Lowes or Home Depot for 3-4 dollars a bag. If any germinate I pot them up in ProMix potting mix with sand on top in 7 oz. clear plastic solo cups with lids. Then they go under lights until end of March, early April. I hardly ever water my seedlings. I end up with about 100 seedlings by the time summer arrives so I have a very small set-up compared to everyone else here.

btw Jim, I was looking at some of your older seedlings that you have posted on your website and was curious if you still have the Lavender striped seedling from 2005?

Kim, this photo is already quite old. Lucas, my oldest is already about 6’3". The 2 oldest sons are in college and the youngest striper(!) had his first prom last night (Jr. in HS). Claire, the baby is already 12!

Don, you are funny!

Regarding the use of plastic coverings, while it does seem to “boost” the seedlings with more consistent moisture, damp-off risk increases and re-acclimating them to out of plastic conditions can be tricky (must be done gradually or you may lose the seedling).

Jim Sproul


After my seedlings have germinated I plant them in a mix called sunshine #4. I grow all of my seedlings under lights in my garage. I started out this year using 4" plastic inserts which gives you 18 inserts(seedlings) per tray. I could see I was going to quickly run out of room with the seeds I had in the refrig so I switched to plastic inserts about half the size and now I have 36 inserts(seedlings) per tray. This is my first year attempting to grow roses from seeds so this setup may not be ideal. I bottom water the trays when they start becoming light and I fertilize them once a week using Scotts 20-20-20 at the rate of 1/4 tsp per gallon once they get their first set of true leaves. Yesterday I discovered that aphids have discovered my garage nursery so I sprayed my seedlings with Merit 75 and now, no more aphids. I live in Argyle, Texas which is about 70 miles south of Oklahoma.

Good Luck,

Bill Cashin