Growing from seeds indoors


I planted several varieties of perennial flower seeds indoors in containers containing sphagnum. Some seeds have reached the true leaf stage and I now want to transfer them to potting up pots made of biodegradable material. Should I use sphagnum in these pots, or can I use potting soil?

How soon can I plant these potting pots in the garden.

I also want to plant flower seeds straight from the seed package into my Toronto garden (Fallingbrook and Kingston Rd area). How soon can I plant them?



Hello, and thank you for writing,

Welcome to spring in Ontario, and good on you for starting your perennials directly from seed: this can often make the entire gardening adventure more exciting, and rewarding!  You haven’t named specifically what you have seeded, which is okay, because right out of the gate, I’m going to suggest that you give this detailed Master Gardener guide a thorough read, and hopefully you should be able to identify your perennials on the included list:

This guide should answer many of your questions regarding potting medium. watering, sunlight, and when to move to next-stage planting outdoors for permanent in situ propagation.  Considering where you’re located, our soil this year is warming almost three weeks later than the seasonal average, so patience is called for.

As for a planting strategy for your annual flowers, I encourage you to consult our TMG Guide for planting seed for annuals. Regarding exactly when to plant seeds outdoors, this is where a bit of gardener’s savvy and intuition comes into play. Depending on which annuals you prefer, you need to consider the size of the seeds, and if there are special germination requirements, how rapidly the seeds are expected to grow, and once germinated, how long will the plants take to bloom, and how cold-hardy are the plants.

You mention that your original containers contained Sphagnum moss: this can be treated as we do peat. Milled Sphagnum is a long-fibre Sphagnum that has been broken up into individual segments, or sprigs. So, to answer your question: a 1 cm. thin  top layer of milled Sphagnum, over a neutral blend of potting mix, could be excellent for germinating many plant seeds. The top layer will be kept moistened, while the planting medium below is not too wet to promote seedling rot.

Also, as the season unfolds, if you can make a few visits to your local nursery, where starter plants are now arriving daily, you should be able to read numerous nursery notes on planting requirements, and also see first-hand what your seedlings should look like as they develop. Happy gardening!