How to Transplant Sprouting Seedlings
One of the joys of home gardening is watching delicate seedlings emerge from the soil as evidence of new life and the first successful passage from seed to a fruitful harvest. The next step, once leggy seedlings seem to be growing out of their “cribs,” is to transplant them into bigger beds where they’ll mature. The process is traumatic for the seedlings and must be done with care if they are to survive. Precise planning is vital for a healthy transition, as is understanding the needs of the specific seedling — all react to temperature and soil adjustments differently.
Refer to your planting calendar to determine the best outdoor temperatures for the survival of your seedlings, and test the soil temperature before transplanting.
Things You Will Need
Soil temperature boosters
Compost and fertilizer
Rocks to secure coverings
Younger seedlings transplant more successfully than those that are rootbound. Harden off your seedlings by introducing them to the outdoor temperatures and conditions slowly. Do this by bringing the seedling trays outdoors during the day, a few hours at a time. This affects the cellular structure of the seedlings so they’ll adjust to the new environment more easily.
Note that cold season crops such as lettuce, onions, beets or peas can be planted directly into the soil as soon as the ground temperatures remain at least 50 degrees Fahrenheit.
Check the soil temperature with a thermometer. Boost the soil temperature by placing a plastic covering on top until it reaches the ideal growing temperature for your type of seedling. If the last frost has passed and it’s time to transplant, prepare the soil by aerating it with a trowel or hoe, or even your hand. This loosens the soil so the roots have an easy time penetrating and establishing themselves. Add organic compost and fertilizer, and mix it thoroughly into the soil.
According to Mother Earth News, plants don’t like to be moved and many don’t survive the transition. Gently remove the seedling plugs from their containers. If the root ball is dry, place it into a pot of water to moisten it before transplanting. Try not to handle the roots, and keep as much of the initial growing soil around them as possible.
The Old Farmer’s Almanac suggests waiting for a warm, cloudy day to transplant, as the plants won’t be suddenly exposed to harsh sun. Dig out the new location for your seedlings with the trowel, spacing them as directed for their growing needs. Place each pod into its new home, planting it deeply and just up to the bottom leaves. Do not cover any of the leaves. Tamp the soil gently. Once all seedlings have been transplanted, water with a gentle spray. If the weather is warm and dry, apply mulch near the base of the newly planted seedlings to retain moisture.
Cover the new bed with landscaping fabric to protect the seedlings from the elements and birds, and to trap the sun, adding warmth. Place rocks around the edges of the cover so it won’t blow up and away. Water through the fabric as needed. Once the weather settles and remains consistent, remove the cover altogether.
A week after transplanting, boost the phosphorus content of the soil by mixing the starter fertilizer as directed for your type of seedling. This promotes root health and growth. Add a cup of the solution to the base of each seedling.
If the newly transplanted seedlings start to show evidence of transplant shock — such as yellowing, wilting or scorching — shade the seedlings for a few hours each day, gradually removing the shade for a few hours until the seedlings return to health.
- The Old Farmer’s Almanac: Planting Calendar
- Mother Earth News: Transplanting Seedlings: How to Do it Correctly
- The Old Farmer’s Almanac: Tips for Transplanting Seedlings
A versatile writer, Jann enjoys research as well as doing the actual writing. A career in television writing, as a magazine editor and celebrity interviewer, Jann adapts to her environment, having traveled the world, living overseas and packing and unpacking her treasures for a new location over 30 times.
How to Transplant Sprouting Seedlings. Sprouting your seedlings indoors gives plants an early start on the growing season, which helps them reach their flowering or fruiting stage earlier in the summer. Small seeds can be sprouted in trays, and these may require transplanting to individual pots so they have room to …
5 Signs It’s Time To Repot Your Seedlings
It’s important to be able to recognize when it’s time to transplant seedlings from the seed tray to a larger pot. Transplanting seedlings a few weeks after starting should be part of your seed starting routine.
We start the seeds in smaller containers because we can control moisture and temperature much better that way, and if you’ve heard me talk much about seed starting then you know my motto is that moisture and temperature are the most important factors in getting good germination.
But once the seeds sprout, they quickly outgrow their seed starting container. It would be a bad idea to let them continue to grow in a pot that is too small. They’ll become nutrient deprived and their roots will grow round and round into a big knot.
Transplanting them into larger pots, helps them develop healthier roots and grow faster. By not restraining their growth indoors, you’re training them to grow big and strong when it’s time to put them in the garden.
But how do you know when to repot seedlings?
There are a few simple things you can look for that are dead giveaways your plants need a bigger pot.
1. They have one or two sets of true leaves
The ideal time for transplanting your seedlings is about 3 weeks after they sprout or when you have 1-2 sets of true leaves. It’s better to get them in new containers before they start to show the signs of stress listed below.
2. The cotyledons are turning yellow and falling off
Cotyledons are the first leaves that emerge from a seed. They are different than the “true leaves.” True leaves are the second and subsequent sets of leaves that grow after the cotyledons emerge.
It is normal for cotyledons to yellow and fall off, but if they’re doing it when you only have 1 or 2 sets of leaves, your plants really need to be transplanted.
3. The true leaves are turning yellow
It’s definitely time to transplant if the true leaves are yellow. This is a sure sign that your plants are starved for nutrients.
4. The roots are wound around and around the root ball
You definitely want to see roots in your growing medium when it’s time to plant, but if they’re circling around the edges of the root ball, then they’re getting too crowded.
5. They’re crowded
You don’t want to overcrowd your plants when they’re young. Some plants will grow taller than others and that will affect how much light the others get. You’ll also get the larger plants sequestering all the nutrients and that will stunt the growth of your other plants as well.
Why transplant the seedlings at all?
You might wonder why we would go to the trouble of repotting seedlings at all? Why not just give them some fertilizer, or better yet, start them in a larger container to begin with?
You’ll be much more successful germinating seeds if you start them in small containers. This allows you to have more control over the temperature and moisture in the seed starting container. We’ve found we have much better sprout rates in the smaller cell trays as compared to using other types of seed starting containers.
You can dose your plants with some fertilizer but that will stimulate growth. They’re already telling you they need more space, why stress them by making them grow bigger in the same small space?
Both of those options are viable alternatives, but you’ll have healthier plants if you transplant instead.
How to repot seedlings
Transplanting seedlings is quite easy to do. You simply need a new container and some potting mix. We recommend a container that is twice as big as what they are in now and a high quality potting mix like Fox Farm Ocean Forest.
We like to mix the potting mix and the seed starting mix in a 50:50 ratio. This is especially helpful for young seedlings who still have tender roots.
Before filling your containers, wet down your soil mixture to ensure even watering after you plant. Then nest your seedling in the new container, filling in around the base of the plant and pressing down to seat it in well and remove air pockets.
For tomatoes, bury the stem leaving only 1 or 2 sets of leaves above the soil line. For all others, plant them level or bury the stem about 1/4 inch or less.
Water your transplanted seedlings well and place them back under the light.
What about fertilizing seedlings?
You can fertilize young seedlings after transplanting as needed. Use a liquid organic fertilizer diluted to half strength. If they tolerate the half strength and seem like they need more, you can up it to full strength.
Don’t fertilize your seedlings until after you transplant them. You don’t want to stimulate growth in a space that is too small.
Do you transplant or repot your seedlings?
Tell us about your experience in the comments below!
You've conquered seed starting. Woot! But do you know when to repot seedlings? Transplanting seedlings is a step you can't skip! Learn the signs your plants are telling you they've outgrown their seed starting tray.