I WAS REMARKING TO my friend Ken Druse this spring about a garden I had just visited, and the primula stands in it that made me jealous and desire more. Only a few primroses are available in garden centers. And if you want to make a large swath, it would be a costly investment.

While I was ranting about something, my phone buzzed and told me that there was a new message. It was a picture of Ken’s newly emerged primula seedlings. He had successfully winter-sown them outdoors for the cost of two seed packets. I asked him to explain how he did this and what other seeds you could sow similarly.

Ken, a gardener in New Jersey (those are his Primula Japonica plants in his canal gardens, above), is also the author of twenty garden books. He’s also my cohost for the Virtual Garden Club, which we host a few times yearly. He is a master propagator and loves to find out how to grow more plants. He also shared his winter-sowing experiment and how-tos for growing primula seeds.

You can listen to my podcast and public radio show for May 29, 2023, using the player below. Subscribe to future editions of my podcast on Apple Podcasts, Spotify, Stitcher. You can also browse the archive here.

Primroses grown from seeds, with Ken Druse

Play this episode Margaret Roach Hi Ken, how are things?

Ken Druse : Hi Margaret! Is spring here? Is it spring? Is it summer? I’m confused.

Margaret: [Laughter. I don’t know what to say anymore. I’m done. Is this a trick question or not? I’d say yes.

In the introduction, I mentioned that I was jealous of the plants I saw in this garden. They were not hundreds of them, but just a large strip along the edge of the beds. It caught my eye because, as a general rule, they are small plants. They look great in mass. Then when you showed them to me, I was like, “Oh my goodness! What’s happening over there?”

Ken: [Laughter. Mass is a good term for it. We see photos of drifts, swaths, and streams of color, but when you buy three plants, it costs $45 plus shipping.

Margaret: Right. Right. Exactly. Exactly. Right. You can have 20 or more if you wish, but…

Ken, You need more than twenty.

Margaret: Yeah. You know what I’m talking about? They do not always stay in the same place.

Let’s go back to the beginning. We did a winter-sowing class last fall, maybe. We talked about everything, from native wildflowers to perennials, to even vegetables that people could winter-sow. It was a really popular class. This was a kind of offshoot. You’ve done this before with perennials and also discussed it a bit in class. How did you start these plants that you displayed in pots, pots, and more pots?

 Ken: I used to collect my own seeds from my plants, but I also tried buying seed packets from Chiltern, England, or Barnhaven, France. It’s hard to find the type of primula that The candelabra primula are quite showy. They grow best along the canal gardens, near the streams.

This year I planted some at the base of an oak tree, and they are blooming like crazy. It took two years to grow a perennial, which isn’t very long for a tough plant. I sow mine in a flat with a sowing medium and cover it with a thin layer of grit. We have talked about grit. It’s similar to coarse sand. Well, it’s chicken grit.

Margaret : Looks like birdcage gravel, but it is not. It’s the grit you use to aid in digestion if you have chicks or anything else.

Ken: Right. Then I would have a flat and cover it with an inverted flat that I bought from the garden center. It’s the kind that drains well, has a grid-like pattern, and I would put a brick to hold it. This year I made a cage from hardware cloth . I placed it in a slightly shady area, and that was it. I built it in January and didn’t think about it again until April.

Margaret: When you say cage, Mickey, Chippie, and everyone else will look for seeds. Mickey Mouse, I’m talking about.

Ken: Primroses, they may not bother them. But they do disturb other things. They want to bury something or go somewhere in my flat.

Margaret: In a way, it’s like animal-proofing, as we’d do with any winter-sown crops, whether we did our vegetables in January or later, to protect it from animals. You said you were putting a seed-starting mixture into a flat. Is this an open flat or an individual pot? What’s going on in there?

Ken: Right. This is an open flat, but they will all look almost identical.

Margaret Ah, it’s an entire flat of the same species or variety. O.K.

Ken: I have them, and I cannot throw them out. I’m sure I sowed hundreds.

Margaret, Let’s discuss that. I’ll play the psychiatrist. Why don’t you throw them out? It is not my real name. Neither can I. All these seeds were just discovered. What happened last year? We had an arid year, and I gave up on my second vegetable sowings because they were too complicated. I found some packs of seeds from a year ago that are now a couple of years old. I was very frustrated. I don’t like to waste or throw away anything.

Ken: I suppose that’s another show [laughter].

Margaret: Yeah, yeah. In any case, I was only teasing. It was an open flat because they were all the same kind. Let’s say that I want to make a few of what I call “community pots” if I wanted four different types.

Ken: Right. They are made in 3-1/2-inch pots. That’s what I did too. This year, due to our classes, I tried two different ways of winter sowing. I sowed the flat with at least 200 primrose seeds I had collected myself. We can also talk about this.

The milk-jug method is a very popular one. You’ve probably seen these in supermarkets, even if you are a vegetarian. They come in a container with a clear top. The container has a dome on top and a reservoir at the bottom, which is usually black.