When To Transplant Seedlings

Transplanting seedlings–your li’l ones are ready for the outdoors, but when do you get them in the ground & off on their own? 

Fret not though. 

Transplanting isn’t as difficult as it sounds. 

After all, you’re only transplanting seedlings–not a kidney.

Transplanting seedlings is typically done when the plant has at least 2 – 3 sets of true leaves (not just cotyledons). Most garden plants are ready to transplant when they’re 2-6 weeks old, and when nighttime temperatures are at least 50-60°F (10-15°C).

With a bit of know-how and care, transplanting is pretty straightforward. 

Plus, it’s fun to get those li’l fellers in the ground & started on their journey to growing up. 

So grab your gloves & a trowel, and let’s get started!

When To Transplant Seedlings

I always get excited about transplanting seedlings, since it means that the tiny plants are launched on their journey in the great outdoors.

If seedlings are growing in tiny containers, you might also need to transplant them to larger containers before they’re ready to transplant outdoors. 

It’s typically best to transplant seedlings when they have at least 2-3 sets of true leaves and/or when they outgrow their container.

Usually, the seedlings are ready about 2-3 weeks after germination, depending on the species and growing conditions (temperature, moisture/humidity, etc.). 

By this time, seedlings will have established a strong root system so they can grow into healthy plants.

Different plants have different transplanting recommendations. For example:

• Tomatoes: Tomatoes should be transplanted when they are 6-8 weeks old and have several sets of leaves. Transplant them into larger pots or directly into the garden.
• Peppers: Peppers can be transplanted when they are 4-6 weeks old. Transplant them into larger pots or directly into the garden.
• Cabbage: Cabbage can be transplanted when it is 4-6 weeks old. Transplant it into larger pots or directly into the garden.
• Basil: Basil can be transplanted when it is 4-6 weeks old. Transplant it into larger pots or directly into the garden.

Other plant varieties can usually be transplanted sooner–for example, lettuces & other greens.

You can transplant seedlings either into larger pots, or just stick them directly in the garden.

Using a seedling tray? See how to transplant from a seedling tray.

Which plants are most sensitive to transplant shock?

OK, so when we’re talking transplanting, we also need to talk about transplant shock.

Transplant shock?!

Yep, it’s a real thing.

Think of it this way: If you’re used to living in sunny Florida, what would happen if you went to Saskatchewan in January? 

You’d be hella freezing.

That’s because you’re not used to the cold.

Same thing with plants.

But slightly different, since we’re also dealing with delicate root systems.

So, the idea is that when you transplant a plant–either a larger plant or more delicate seedlings–you want to treat it gently.

That way, it’ll be off to a smooth start in its new home.

Transplant shock can occur in any plant, but some plants are more sensitive to it than others. 

See why your seedlings are turning yellow (& how to fix it).

Plants that are more sensitive to transplant shock:

• Delicate herbs: Basil, cilantro, and parsley.
• Leafy greens: Leafy greens like lettuce, spinach, and kale.
• Peppers
• Tomatoes
• Sunflowers

To minimize transplant shock, handle the seedlings gently, & keep the roots intact. Basically, you want to disturb the roots as little as possible when transplanting. 

Also, most plants like to be hardened off before transplanting–especially if you’re transplanting them to very different conditions (e.g., indoors to outdoors).

To harden plants off, you need to gradually introduce them to their new home.

For example, at first, just a few hours at a time, then increase their time in the new place over the span of several days.

When To Transplant Tomato Seedlings

Like most other garden plants, tomatoes do best if you wait until they’re 6-8 weeks old and have several sets of leaves. 

Keep in mind that tomatoes can easily get transplant shock.

So, take special care when transplanting them: handle them gently and do NOT disturb their roots. 

Also, give them a good watering after transplanting.

Just make sure they’re not waterlogged or sitting in soggy soil.

That’s a sure recipe for root rot. Ech…

Tomatoes are sensitive to low temperatures and can suffer from transplant shock if it’s too cold. 

A study by the USDA found that tomato seedlings are sensitive to temperatures below 50°F (10°C).

So, while they can survive cooler temperatures, tomatoes might not recover if they’re kept below 40-50°F. 

For example, a study by the University of California-Davis found that tomato seedlings exposed to temperatures below 50°F (10°C) for even just a few hours showed reduced growth and increased susceptibility to disease and pest damage.

So, to minimize the risk of transplant shock, transplant tomato seedlings when the temperature is above 50°F (10°C). 

If nighttime temps are expected to get colder than that, you can cover tomato plants with row covers or plastic to protect them. 

See why your tomato seedlings aren’t growing.

When To Transplant Lettuce Seedlings

Like tomatoes, lettuce needs to be transplanted when it’s 4-6 weeks old and has several sets of leaves. 

Some lettuce varieties are more tolerant of cool temperatures and can be transplanted earlier in the season, while others are more sensitive and should be transplanted later when it’s warmer.

Lettuce varieties that are more tolerant of cool temperatures and can be transplanted earlier in the season include:

• Butterhead lettuce
• Romaine lettuce
• Summer crisp lettuce

Lettuce varieties that are more sensitive to cool temperatures and should be transplanted later in the season when it’s warmer include:

• Loose-leaf lettuce
• Batavian lettuce
• Red leaf lettuce

A study by the USDA found that lettuce is sensitive to low temperatures and can suffer from transplant shock if exposed to temperatures below 50°F (10°C). 

So, make sure you transplant your lettuce seedlings when the temperature is above 50°F (10°C).

Remember to avoid disturbing the roots to make sure that the lettuce seedlings stay healthy when you transplant them.

When To Transplant Pepper Seedlings

By now you should be clued into the theme that seedlings need to be at least 4-6 weeks old before transplanting. 

Peppers, though, typically do better when they’re a bit older–usually 6 to 8 weeks–before transplanting.

Some pepper varieties are more tolerant of cool temperatures and can be transplanted earlier in the season, while others are more sensitive and should be transplanted later when it’s warmer.

Pepper varieties that are more tolerant of cool temperatures and can be transplanted earlier in the season include:

• Bell peppers
• Ancho peppers
• Poblano peppers

Pepper varieties that are more sensitive to cool temperatures and should be transplanted later in the season when it’s warmer include:

• Jalapeno peppers 
• Cayenne peppers
• Serrano peppers

Like other garden plants, peppers tend to do better when they’re transplanted when temperatures are above 50°F (10°C).

When To Transplant Sunflower Seedlings

Who doesn’t love sunflowers?

The thing is, even though wild sunflowers will grow most anywhere–often in disturbed soil & vacant lots–most sunflowers don’t like to be transplanted.

So, just be extra careful when transplanting sunflowers.

Sunflower seedlings can be transplanted when they’re 2-3 weeks old, and have at least their first set of true leaves. Sunflowers are sensitive to transplant shock, so take extra care to disturb their roots as little as possible.

Like most other plants, sunflowers do better when they’re hardened off.

So, you want to gradually introduce them to their new home.

That means putting them outdoors just for a couple hours at first.

Then, each day, gradually increase the amount of time by a couple hours.

That way, they gradually get acclimated to their new environment. 

Technically speaking, hardening off allows the plant to produce hormones that allow it to adapt to its new conditions (temperature, heat, cold, etc.).

Growing sunflowers in pots? Check out our complete guide.

When To Repot Seedlings

OK, so you’re busy & you haven’t had time to repot all your seedlings.

I get it.

We’ve all been there.

So, as a general rule, you want to repot seedlings when they’ve outgrown their container, their roots are visibly growing through the bottom of the container. 

Depending on the plant and the size of its seedling container, this can happen as soon as 2-3 weeks after germination.

The following is a list of common garden plants that should NOT be repotted as they are sensitive to root disturbance and can suffer from transplant shock. 

Or, if you really need to transplant them, just be super careful about NOT disturbing their roots:

• Tomatoes
• Peppers
• Eggplants
• Sunflowers

The plants above usually grow best when started directly in the ground or in their final container. 

Transplanting can cause the plant to go into shock, which can reduce growth and fruiting.

When To Transplant Seedlings Outdoors

OK, so you’re getting excited about getting those li’l seedlings outside & in the ground!

But is it too early?

Too cold? 

Too hot?

How do you know when the best time to plant seedlings outdoors?

Generally, the best time to transplant seedlings outdoors is when nighttime temperatures are at least 50°F (10°C). Some plants–like lettuce & cauliflower–are more tolerant of cool temperatures and can be transplanted earlier in the season. Other plant varieties are more sensitive and should be transplanted later when it’s warmer–for example, cucumbers & eggplants.

The following is a list of common garden plants and their ideal (and lowest) temperature range for transplanting outdoors:

Wrapping it up

OK, so there you have it. 

Most plants are pretty hardy and can tolerate transplanting. 

But to boost the chances of transplanting success, make sure:

• Seedlings have at least 2-3 sets of true leaves
• Seedlings are 4-8 weeks old.
• Minimum nighttime temperatures are at least 50°F (10°C)
• Do NOT disturb the roots.