Black-Eyed Susans belong to the genus Rudbeckia, which contains over 25 species of flowers. Most of these species will produce flowers with yellow petals and dark black centers (and very showy). Each species has its own native range within North America, with some overlapping. Rudbeckia flowers are herbaceous perennials, meaning they will die back each year but return the following Spring. They love full sun and well drained soil, make good cut flowers and a nice addition to any flower garden.
Most members of the Rudbeckia genus prefer full sun and well draining soil. With certain species performing better in semi-moist or dry environments. It is relatively easy to find a species to suit your needs in your garden.
Black-Eyed Susan Seeds and Cold Stratification
Rudbeckia flowers are relatively easy to propagate and grow from seed. But, take care to not plant them too deep. Also, studies have shown that Black-Eyed Susan seeds should be cold stratified or winter-sown to achieve a high germination rate. The seeds from all Black-Eyed Susan need to go through a winter in order to achieve a high germinate rate. So, you will have to either winter-sow the seeds or stratify the in the refrigerator in order to get a high germination percentage. You can learn a few ways to cold stratify seeds by clicking here.
How long do Black-Eyed Susan seeds need to Stratify?
I’ve generated the table below to show how many days are recommended for cold stratification, as well as their growing characteristics. If you winter sow you can disregard this table (as long as temperatures dip below 40F at night (5 C) ). Just make sure you winter sow by January, or by February if in colder zones.
The highest germination percentages will occur with longer stratification times. And you will get that with late Fall/ Early Winter sowing of seed. Besides, that is how mother nature plants these seeds, and why shouldn’t you do the same?
Black-Eyed Susan Reference Table
|Common Name||Species Name||Moisture||Height||Bloom Size||Seed Planting Depth||Stratification||Bloom Time|
|Perennial black-eyed Susan||Rudbeckia Fulgida||Dry-Medium – Well Drained||3 ft (1 m)||3-4″, 7-10 cm||0-1/16″ (0-1.5 mm)||30 days||Mid-late summer|
|Sweet Black-eyed Susan||Rudbeckia Subtomentosa||Dry-Moist – Well Drained||3-5 ft (1-1.5 m)||3-6″, 7-12 cm||0-1/16″ (0-1.5 mm)||30 days||Late Summer|
|Black-eyed Susan||Rudbeckia Hirta||Dry-Medium – Well Drained||1-3 ft (30 – 100 cm)||2-4″ 5-10 cm||0-1/16″ (0-1.5 mm)||30 days||Summer|
|Brown-eyed Susan||Rudbeckia Triloba||Dry-Moist – Well Drained||3-6 ft (1-2 m)||1-3″, 2-7 cm||0-1/16″ (0-1.5 mm)||30 days||Late Spring-Late Summer|
Planting Black-Eyed Susan (Rudbeckia) Seeds – Materials Required
Now that you have stratified seeds (or are preparing to Winter-Sow), you should gather the following materials:
- Pots – this can be a common seed starting six-pack, or even just use an old plastic container with holes drilled in the bottom for drainage
- Potting soil or seed starting mix
- Small garden shovel, or trowel
- Spray bottle for watering
- Seeds – Black Eyed Susan seeds are readily available at many nurseries.
How to Cold Stratify Liatris Seeds
You can approach this one of two ways. The first method (my preferred) is just to winter sow the plants. You just plant them as you normally would, but keep them in a covered plastic container, or dome with holes poked in for air movement. Then, just place the seeds outside, and voila.
The other way to cold stratify seeds is to simulate the cold/moist winter by placing them in the refrigerator. To do this, either mix the seed with moist sand in a bag. Or you can use a moist paper towel.
How to plant Black-Eyed Susan Seeds
Although you can plant your seeds anytime during the Spring, I find that I have the most success when I do so in early Spring. This provides warmer daytime temperatures, but not so much where my pots will dry out.
- Fill pots with moist potting soil, to about 1/2″ (12 mm) below the top of the pot. Your soil should be moist, and it is easiest to moisten it in a bucket before putting it into the pot. However, you can easily do it if you spray water as you add soil to the pot. You don’t want the soil sopping wet, just moist.
- Place 3-5 seeds in each pot or cell. Press them firmly into the dirt.
- Lightly cover the seeds with with just a dusting of soil, no more than 1/16″ deep (<1 mm)
- Take a few more seeds, and press firmly into the moist soil. Do this so they are exposed from the top, but have good contact with the soil everywhere else.
- Mist the seeds with a spray bottle, or pump sprayer – taking care not to wash everything out.
- Place seeds in an area where they will receive morning sun, and keep moist.
- Germination should occur once temperatures are reliably above 50F at night (if winter sown). Otherwise, you should expect seedlings within two weeks (if stratified in the refrigerator).
- Finally, you need to care for the seedlings until they are several inches high. Finally transplanting them into their final location. Often, I will transfer seedlings to large pots (4″ square or round) to grow them to a larger size. It helps ensure success for getting a plant to survive the first year.
- Note! Rabbits do love to eat young Black-Eyed Susan Plants. Consider protecting them with Liquid Fence or chicken wire the first year (at least).
Here is a short video I made some years ago on how I plant my seeds – hope you enjoy!
Also, if you have any questions – Just go ahead and ask me in the comments!
Some notes about watering, and how moist should ‘moist soil’ be
When I am germinating any seed, I generally water them in the mornings before I go to work. When the forecast calls for sunny days or hot weather, I will spray water on them until the soil is black/moist, and the pot feels heavy. That way I know I have water throughout the entire depth of soil inside the pot.
When I return in the afternoon, I will check to see if they need to be watered again. If the pot feels light weight, or the top of the soil is very dry I will add more water via a pump sprayer until the pot feels somewhat ‘heavy’. I will continue this these two processes until germination.
Once the seeds have germinated, and I have seedlings I will avoid watering in the afternoon, and almost never water at night. The reason I avoid this is because of something called damp-off disease. Damp-off disease is a fungus that can weaken the stems and kill the young seedling. So, to avoid this it is best to not have the seedling sit in fully saturated soil overnight.
How and When to Transplant Black-Eyed Susan seedlings to the garden
Once your seedlings have grown to be 3-4″ tall, they are more than ready to be placed into their final location.
- Dig a hole to just below the depth of the pot, and twice as wide.
- Put a handful of compost at the bottom of the hole, and gently mix it in.
- Water the hole, and wait for the water to drain.
- Plant your Black-Eyed Susan, filling in around the pot. Pack soil firmly.
- Protect your seedling. Apply liquid fence (it really works) or put some fence around the plant and stake it.
You can transplant your seedlings in the summer – just know that it may require supplemental water for several weeks if it is in an area prone to drought. You can plant your seedling as late as nature lets you! So, even if it is in December, if the ground isn’t frozen you can plant the plant. The roots will still grow just fine and establish themselves, even if it is cold temperatures above ground.
How long does it take to grow Black-Eyed Susan from Seed?
Generally, Rudbeckia will not flower until it’s second year after seed germination. Although, I have had Brown-Eyed Susan bloom the first year (Rudbeckia Triloba). Rudbecika is a large perennial that requires significant root development. So typically you won’t have any flowers the first year. It will just look like a large, leafy plant on the ground. But – the second year of life most Black-Eyed Susan’s will produce blooms. And in the 3rd year of life, you will be treated to a massive display if planted in the flower’s preferred conditions of full sun and well drained soil. And after the 3rd year, you should consider dividing your Black-Eyed Susan plants (Mainly Sweet Black Eyed Susan and Perennial Black Eyed Susan) to keep them looking healthy and vigorous.
Are Black-Eyed Susan / Rudbeckia Difficult to Grow from Seed?
Rudbeckia can be a little tricky to germinate from seed. This primarily arises from people being unfamiliar with, or not performing a cold stratification/winter sowing of Black-Eyed Susan Seeds. Also, there are some references out there that tell you to plant the seeds deep, when you should really only lightly plant them. Surface sowing to just under the surface of soil is the proper depth for planting Black-Eyed Susan Seeds. I’ve had the most success by planting them on the surface, and just raking them into the soil.
So, I hope you enjoyed this article. If you would like to learn more about Black-Eyed Susans , then read our post on Black-Eyed Susans here!
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