Understanding Stock

This is the first topic I want to tackle because I was unable to find information on the Internet.

I first met stock while doing the floral arrangements for my cousin's rehearsal dinner. While there are many stories around that whole week - one of the benefits was meeting and learning about matthiola incana!

I was interested in it because it looks a heck of alot like snapdragons (the bride's favorite) and smells spicy. Amazing. Fantastic!!

It also reminds me of delphinium; just on stronger, woodier stems.

I've read it was a standard in Victorian style gardens and is a plant that your Gramma used to have in her garden. It fell out of fashion but has been rediscovered!

What is stock?

The scientific name is matthiola incana. It has a number of common names, including Brompton stock (european reference), hoary stock, tenweeks stock, night-scented stock and evening-scented stock. Stock can be grown as an annual in places that freeze over winter, and as a biennial in warmer climates. It will grow over 12 inches. Staked, it can easily grow over 24″.
Stock is in the family brassicaceae, along with broccoli, cabbages and mustards. Many in this family are known for their four petals, hence the previous family name of Cruciferae, meaning “bearing the cross.” See, my Latin in high school comes in handy sometimes!

Here you can see the four petals much clearer on the single floret.

Stock comes in a variety of colors. I chose an off-white for my own bridal bouquet. I wanted to feel like I should eat my bouquet...and it was sooo wonderfully smelly that I just had my nose stuck in it most of the reception.

Two flower conditions - single and double florets

While the double floret stock individuals are those coveted by florists and gardeners, the downside to these beautiful flowers is that they are sterile. The double flowering characteristic is caused by a homozygous recessive gene. Single flowered plants thus can propagate progeny that are homogeneous recessive, heterogeneous or homogeneous dominant. Most varieties available today have been in-bred to only produce homogeneous recessive and heterogeneous offspring.

You will notice here on these double floret petals that there are no stamen (male organs) or pistil (female organ). You just have the spent ends of the floret where the petals fell off.

I'll cover more about selection below, and how you can figure out whether or not young plants will be singles or doubles.

Parts of the plant and seed saving

I am not making assumptions that everyone is a botany geek like me. So let me cover some parts of the plant.

Here you can see the tall main spike of the single floret stock. As described by their family, the flower consists of four petals. In the middle, you will be able to see the elongated green pistil (female organ), possibly surrounded by yellow, pollen covered stamen (male organ; top floret).

The end of the female organ, the stigma, is sticky, and that is how the pollen granules get from the stamen to the female organ. Reproduction occurs as the male gamete from the pollen goes from the stigma, into the pistil and ends up in the ovule at the end base of the floret, closest to the stem.

Single floret stock produce stamen on each floret and separate stamen structures. Generally, stock is self-pollinating.

As part of the stock’s growth cycle, the pistil continues to grow and elongate, with the petals eventually falling off. What remains is a fertilized or unfertilized pod resembling a small, narrow stick or pea pod. Harvest seed pods once they turn yellow/brown.

As with the rest of the brassicaceae plants, the seed pod features seeds in rows, divided by a thin septum. Simply separate the two halves of the pod with your fingers. I find it easiest to grab it from the stem end.

And pull apart the septum and the shell. Then do the same process for the second side.

Store your seeds in a dry place. Not all seeds will be brown. I found that even seeds that are slightly green will germinate. As noted above, your seeds will be approximately 25% or more (dependent on the inbreeding) double floret. Of those single floret plants, approximately one third will be homogeneous dominant and not able to produce double floret offspring.

Seeds do require stratification to germinate. If you are doing seed saving, I recommend putting the seeds in the fridge for a week or so. Or, like me, you put them in a jar and keep them in your outdoor greenhouse/plant shed.

Either way, stock do best with some level of stratification and giving them a "winter."

Seedlings and selection

As outlined above, depending on what you want to grow, you can eliminate all the less attractive single floret individuals from your garden. You will just need to rely on another source for your seeds. My favorite seed catalogs are: Johnny’s Seeds (taking home orders starting 4/28/20), Territorial Seed and Aerogarden. I will write more on my Miracle Grow Aerogarden later.
I’ll cover my germination tricks in a future post that I’ve proudly passed on to my Dad! But for double floret stock selection according to Johnny’s Seed: “After germination, while the seedlings are still in the cotyledon stage, expose the seedlings to temperatures of 40-45°F/4-7°C for 3-4 days. Select lighter green seedlings with an oval shape; these will produce double flowers. Discard very small seedlings, ones that are darker green in color, and those with rounder shaped cotyledons; these will produce single flowers.”

Back to plant anatomy: cotyledons are the first two leaves from the seed. If you split a bean, the two sides are the two cotyledon leaves. You are looking for oval cotyledons for double floret stock.

If like me, you weren't able to see it early, here are some pictures of the adult leaf (any leaf after the cotyledon stage) difference.

There are 3 individuals here - two are oval leafed, and one is round leafed. I now remove my "round" leaf individuals and keep them separate so that I can have breeding stock. Yes, the pun is intended!

As the plant grows, double floret stock will have lobed adult leaves (left). Single floret will always have rounded leaves (right).

Growing Stock

Stock are slow growing annuals that require colder weather to set their flower heads. If you are planting them directly outside, I’d recommend starting your seeds indoors and getting them a head start on your season. Its a wonderful seed to start around Valentine’s Day.

Stock are considered cold-hardy and can be grown outside, without a cold frame or greenhouse protection to 5 degrees Fahrenheit (Zone 7). I haven’t tested that yet – but I have had parsley and mint over-winter well with slight mulching to protect from the worst of the winter cold.

I germinate seeds using the fast-food napkin method with indirect sunlight, then transfer to 1 inch or 4 inch pots or whatever is available. I grow under a grow lamp (3 hours blue/red) and indirect sunlight. As the plants are large, I do only one or two germinated seeds per pot. After the likelihood of frost has past, which is May here in the lovely northern Virginia mountain climate, I can transplant into a flower bed with full sun (6+ hours of uninterrupted sunlight).

As explained above, stock require colder weather to set a flower head, which is below 80 degrees. Thus, by giving my plants the lead time indoors, they are able to set a floral head in May and early June before it gets sweltering hot. The other option is to grow as a biennial as explained below.

To grow them as a biennial, “the A-Z of Garden Flowers” recommends that you sow seeds in June/July. In the fall, move them to 5 inch pots and overwinter the flowers in a cold frame or greenhouse. Winter watering requirements are small: water when the plant begins to wilt. Move outdoors once past frost. Stake to support the spikes begin to grow.

Cutting advice: The double floret individuals can honestly last a very long time and are great cut flowers. Johnny’s Seeds recommends cutting them once atleast one-half of florets are open. “The A-Z of Garden Flowers” recommends to “scald stems after picking and change vase water every couple of days.”


Since stock is in the cabbage family, all the same pests that apply to cabbages and broccoli are your problem insects. That includes aphids, cabbage looper/moth, cabbage webworm, cross-striped cabbage worm, diamondback moth, imported cabbageworm, harlequin bug, among others.

This year I am going to try systemic Neem Oil treatment to some of my outdoor plants to hopefully kill all the destructive pests but leave my predators alone. My backyard has a healthy population of Preying Mantis and I’m working on increasing the Lady Bug population.

Side note – remember to not use Neem Oil anywhere around your butterfly garden since the wonderful Monarch Butterfly Caterpillars do eat the Milkweed plants. These plants are being sacrificed to the hungry “cats” as they were grown to do!


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