Ready, start, go – 2023!

Early to mid- February is a good time for us, in cold Northern Hemisphere regions, to start seeds under indoor lighting. This way, by late April-May the seedlings can be acclimatized outdoors, and in some cases planted in the ground during the summer (fast growing species). Gaining 2-3 month of growth for our short season is a big plus!

This is an update of a 2022 post with few updates; also posted it in the Germination page now.

I have written about indoor sowing with other occasions, but a reminder is always good.
‘Warm germinators’ is the term used in the BotanyCa catalogue to describe the dry seeds that will germinate at room temperature (+/- 17-21C) after a certain period of time (a few days to a few weeks).

Many species will germinate easily after a regular sowing, others require various treatments before sowing in order to germinate at warm.

I think it is a very good method especially for various rockery species which benefit from being planted in the ground at a young stage (various Arenaria, Bukiniczia, Campanula, Dianthus, Draba, Edraianthus Silene, Anthemis, Hedysarum, Oxytropis, Papaver species).
When started in February, they can be ready for planting in the ground by June; some may even produce a flower or two!

What treatments are used for various species, when starting them indoors?
Acid gibberellic treatment – an easy way to prepare a solution: Here
Hot water treatment for species with hard seedcoats: Here
Soaking and nicking the seeds, as well for hard seedcoats: Here
More advice for sowing small/fine seeds: Here

With so many light systems available nowadays, it is worth to try sowing and growing indoors a few species. It is most rewarding and also therapeutic to grow something new during the winter months!  Start with just 4-6 species if you are new at this. They will be perfect for a small trial-out ‘rock container’ planting in the summer.

You know the concept of going to do the grocery when you are not hungry, right? Your ‘plants budget’ will certainly improve when the garden centers start offering perennials in late spring!

*It can happen that species given as ‘warm germinators’ to not ‘comply’ to the rule, and vice-versa, ‘cold germinators’ starting to germinate at room temperature. Every year there is a new surprise. The source of seeds: wild coll. versus garden coll., growing conditions of the mother-plants and other factors, all can influence the germination pattern.
If a known ‘warm germinator’ refuses to comply, move the pot in cold location for 3-4 weeks (fridge OK) and then return it to room temperature. No matter what, it is best to keep your pots for 2-3 years if possible; some seeds can enter a second dormancy and will need multiple alternate cycles of cold/warm for germination.

What can we start indoors?

The list below is not exclusive and it only contains cold hardy genera/species that I have personally germinated over the years at room temperature. I made notes for the species that I have started using GA3 (by habit, otherwise use cold/moist stratification) and those that will germinate best and faster if using a HWT (hot water treatment).

I recently included in the list Glaucidium palmatum – I just treated older seeds (2018/2019) with GA3 and there is almost 100% germination! It is not a fast growing species, but easy to germinate; the same goes for Podophyllum hexandrum.
Some of the species can be found in the SEEDS LIST.

 

Wash your pots (best practice for indoor sowing), prepare a sowing mix, labels, the seeds and then go! Start first with those species which take longer to germinate (or unknown) and leave the very fast germinators for early March (for example Papaver, Silene species).
Are you ready? Start sowing – the winter will be over in a blink of an eye and our gardens in bloom again :)

You can also find more ‘warm germinators’ by checking out the Germination guide of the Ontario Rock Garden & HP Society page: Here