From seed to the first harvest, I usually think of shiso as a roughly 6-10 week project, although the exact timing depends on temperature, sunlight, soil, and whether you start from seed or a young plant.
The important thing is not to focus too much on an exact number of days. Shiso responds strongly to growing conditions, so a plant growing in warm, sunny weather can develop much faster than one planted too early in cool soil.
How Long Does Shiso Take to Germinate?
The first stage is germination, and this is where patience helps.
Shiso seeds are very small, so I don’t bury them deeply. I press them gently into the soil surface and keep the area consistently moist.
In warm conditions, seeds can begin germinating in about 1 to 3 weeks. Sometimes they appear sooner, while cooler conditions can make the process take longer.
One thing I learned with small herb seeds is not to keep disturbing the soil to see whether anything is happening. Keep the surface moist and give them time.
Once the first seedlings appear, make sure they get plenty of light. This helps prevent them from becoming thin and stretched.
How Long Until Shiso Seedlings Become Established?
After germination, the seedlings need some time to develop a stronger root system.
During the first few weeks, growth can seem slow. I wouldn’t worry too much about this. The plants are putting energy into their roots and establishing themselves.
Once the seedlings have several true leaves and begin producing new growth more consistently, you’ll usually notice them starting to grow much faster.
This is also a good time to thin crowded seedlings. Giving the strongest plants enough room makes a noticeable difference later in the season.
When Can You Start Harvesting Shiso?
For me, this is the most useful part of the growing timeline.
You don’t necessarily have to wait until shiso reaches its full size before harvesting. Once the plant is established and has several healthy leaves, you can begin picking a few leaves at a time.
Under good growing conditions, that can be around 6 to 10 weeks from sowing.
I prefer harvesting lightly at first. Taking too many leaves from a small plant can slow it down, while picking a few mature leaves encourages you to keep the plant productive without putting too much stress on it.
As the plant gets larger, you can harvest more frequently.
Why Does Shiso Sometimes Grow Slowly?
If your shiso seems to be taking forever, don’t immediately assume something is wrong with the seeds.
Temperature is often the first thing I check.
Shiso is a warm-season herb. If the soil and air are still cool, germination and early growth can be noticeably slower.
Lack of sunlight is another common reason. A plant sitting in deep shade may survive, but it won’t usually grow as vigorously as one receiving several hours of good sunlight.
Watering also matters. Young plants don’t like being allowed to dry out completely, but constantly wet soil can cause its own problems.
If growth is slow, I check the basics first:
- Is the plant getting enough sunlight?
- Is the soil staying reasonably moist?
- Does excess water drain away?
- Is the plant crowded?
- Is the weather warm enough?
Fixing one of these simple problems can sometimes make a bigger difference than adding fertilizer.
How Fast Does Shiso Grow in Warm Weather?
Once temperatures are consistently warm, shiso can really take off.
This is the stage when I notice the biggest difference from week to week. A plant that looked small a couple of weeks earlier can suddenly become noticeably bushier.
Regular harvesting can also help keep the plant producing fresh shoots. Instead of allowing one main stem to grow straight upward, pinch the growing tip above a pair of leaves.
This encourages branching and gives you a fuller plant.
If you’re growing shiso mainly for cooking, I find this approach much more useful than simply waiting for the plant to reach its maximum height.
Does Shiso Grow Faster From a Transplant?
Yes, starting with a young plant can save you some time.
When you buy an established shiso plant, you are skipping the germination and early seedling stages. After transplanting, the plant may need a short adjustment period, but once it starts producing new growth, you can usually move toward harvesting sooner than you would with newly sown seeds.
However, I still prefer seeds when I want several plants. They’re inexpensive, and once you get the timing right, growing a batch of shiso isn’t difficult.
Young plants are especially convenient when you’re planting later in the season and don’t want to wait for seeds to germinate.
How Long Does Shiso Produce Leaves?
The growing period doesn’t end after the first harvest.
With regular picking and good conditions, shiso can continue producing leaves for much of the warm growing season.
The key is to avoid letting the plant become completely dominated by flowers if your main goal is foliage. When flower buds appear, you can pinch them off to encourage the plant to continue putting energy into new leaves.
I usually leave a few plants or a few flower clusters alone if I want to collect seeds for the following season.
A Simple Shiso Growing Timeline
If you want a rough idea of what to expect, this is the timeline I use:
Weeks 1-3: Seeds germinate and tiny seedlings appear.
Weeks 3-5: Seedlings develop more true leaves and begin establishing their roots.
Weeks 5-7: Plants start producing more noticeable new growth.
Weeks 6-10: Light harvesting can usually begin if the plants are healthy and well established.
After week 8: Regular harvesting and pinching can help keep plants bushy and productive.
These are only general guidelines. Warm weather, good sunlight, and healthy soil can speed things up, while cool weather or poor growing conditions can slow everything down.
My Tip for Getting Shiso Growing Faster
If you want to shorten the waiting time, don’t try to force the plant with lots of fertilizer.
Instead, get the growing conditions right from the beginning.
Wait until the weather is warm enough, use well-draining soil, keep the seedbed moist during germination, and give the plants plenty of light. Once established, regular harvesting and pinching will help maintain fresh growth.
I’ve found that healthy shiso doesn’t need much fussing over. The biggest improvement usually comes from getting the basics right rather than trying to make the plant grow faster with extra products.
Final Thoughts
So, how long does shiso take to grow? In good conditions, you can expect roughly 6 to 10 weeks from sowing to the first useful harvest, with the plants continuing to produce leaves afterward.
Don’t be discouraged if your seedlings take a little longer than expected. Shiso is very sensitive to temperature during the early stages, and a few extra days of cool weather can make a noticeable difference.
Once the weather warms up and the plant becomes established, you’ll likely find that the waiting is worth it. For a more complete look at planting, watering, spacing, and harvesting, see my guide to shiso growing time.