Rosemary can be a bit more complicated to grow from seed than a lot of other herbs but if you want to do it, you have come to the right place. I will explain everything you need to know to sow rosemary seeds successfully in this article including which items you need, how deep to sow the seeds, when you should do it, and how to care for the seeds and seedlings once you have sown them.
One thing you should know before we get started is that rosemary seeds usually have a low germination rate. However, you can increase it by placing the pots in a refrigerator for 2-3 weeks after you sow the seeds in them. This process is called cold stratification and it simulates a short winter dormancy, which can help the seeds germinate more easily.
If you have attempted to grow rosemary from seed before without success, this might very well be why, but there are a couple of other potential reasons why it sometimes won’t grow, which I cover in the article on this link.
Now that you know that, let’s get started.
Items Needed When Sowing Rosemary Seeds
To make it as easy as possible to sow your rosemary seeds, make sure you find the items you need before you start.
Here is what you need to successfully sow rosemary seeds.
- Rosemary seeds
- Seed starter soil
The first thing you need is, of course, some rosemary seeds. If you haven’t already selected a variety, I recommend that you read the article on this link, which I wrote to help you find the right variety for you.
You can use more or less any pot you want, but make sure it has good drainage. If you want your rosemary to grow in the ground at some point, I recommend using some small biodegradable seed starter pots like the ones I used in my photo above. When the plants are large enough, you can place them in the ground and they will break down over time.
You can also just use a regular clay pot like the ones in the back of the photo. When I wrote this article, I sowed rosemary seeds in both a clay pot and some of the biodegradable pots and both seem to work great.
If you are not sure if you want to keep your rosemary in pots or the ground, read the article on this link, where I compare the advantages of both methods. No matter what, I still recommend starting the plants in pots since it is easier to manage while the plants are small.
Remember to sow more than just one seed in each pot since the germination rate isn’t very high. I usually sow 3-5 and it seems to work well.
Best Time to Sow Rosemary Seeds
The best time to sow rosemary seeds is late winter or early spring. The precise time depends on where you live, but a good rule of thumb is 2-3 months before there is no risk of frost outside. That way, the plants are large enough to be put outside in late spring when they can get a lot of sunlight.
Knowing how long it takes for rosemary seeds to germinate can help you plan when to sow them. It took about 2 weeks before the rosemary seeds I planted for this article started sprouting, although most sources I could find said 3-4 weeks, so expect it to take longer than with most other herbs.
While large, established rosemary plants can usually survive a little bit of frost, young plants and seedlings are more fragile. Because of this, it is important that you keep them inside for the first 2-3 months after sowing and don’t put them outside until there is absolutely no risk of frost.
This rule also applies if you want to keep your rosemary in pots instead of transplanting them into the ground. In that case, just put them outside in a sunny spot when there is no risk of frost.
When you put your rosemary outside, it can help the plant survive the transition if you harden it off before keeping it outside for good. I go into more detail with this as well as how to find out precisely when to put your rosemary outside in the article on this link.
How Deep and How Far Apart Should You Sow Rosemary Seeds?
One of the most important things, when you sow seeds, is to bury them at the correct depth. It is a common mistake to bury seeds too deep, which can prevent them from ever sprouting, so let me explain how you can avoid that when you sow your rosemary seeds as well as how far apart the plants should be.
Rosemary seeds should be sown no deeper than about a quarter of an inch (about half a centimeter) in the soil to have the best chances of germination.
Plant your rosemary at least 12 inches (30 centimeters) apart to make sure they have enough space. This might seem like a lot but as you can read in one of my other articles, rosemary can get very large with time.
If you got your rosemary seeds from a seed packet similar to the one I have in the photo above, you can usually read this information on the back of the seed packet.
If you, like me, primarily want your rosemary to grow in pots, horizontal spacing is not much of an issue since you can always just move them around as needed. Just make sure you don’t sow too many seeds in the same pot. I recommend 3-5 seeds unless the pot is larger than 12 inches (30 centimeters) in diameter. In that case, use a few more seeds.
How to Care for Rosemary Seedlings After Sowing
Once you have sown your rosemary seeds according to the information I have shared in this article, you should know how to take care of them. First, how to take care of them until they sprout and then how to take care of them as they grow. I explain what you need to know now.
As I mentioned at the beginning of this article, rosemary seeds usually have a low germination rate, but you can increase it by placing the pots in which you sowed the seeds in a refrigerator for 2-3 weeks.
It is important that you keep the soil as consistently moist as possible. If it dries out after having been watered, the seeds can die before they ever sprout and if it is too wet, the seedlings can drown.
As soon as your seedlings begin to sprout, place them in a spot where they can get plenty of sunlight and high temperatures. At this point, you should start watering them slightly less often than before to prevent overwatering. I have written a guide on how to water rosemary with all the information you need, which you can find on this link.
Once your rosemary plants reach about 5-10 inches (12.5-25 centimeters) in height, it is usually a very good idea to transplant them either into the ground or into larger pots to prevent them from becoming rootbound. I have a guide where I explain and show how to do that on this link.