How to Transplant Seedlings from Seed Trays: A Step-by-Step Guide

Up-potting, or potting up, refers to moving a plant from a smaller to a larger pot. Most of the time, this is done to give the plant more room for its roots to spread out and grow, which can help it be healthier and live longer.

Gardeners choose to move seedlings to bigger pots for a variety of reasons, such as to help the roots grow, make sure there are enough nutrients, keep the plants stable, improve their health, and extend the growing season for more crops.

Whether you’re a seasoned gardener or a beginner, this guide will teach you what you need to know to make sure your plants do well after you pot them up.

Up-Potting: When and Which Plants to Up-Pot

Most plants benefit from being moved to bigger pots, but plants that grow quickly or have large root systems need it the most. Here are some tips to help identify which plants might benefit from up-potting:

• Make sure the pot is the right size. If your plant’s size doesn’t seem right for its pot, it may be time to move it up. As a general rule, the plant’s height should be about the same as or less than the diameter of the pot.
• Watch the Roots Grow: One of the clearest signs that a plant needs to be repotted is when the roots start to stick out of the drainage holes or show up on top of the soil. This means the plant is too big for its pot and needs more space to grow.
• Keep an eye on how much water your plant needs. If it needs more water than usual, it could be because its roots have filled up the pot, leaving less soil to hold water.
• Watch for Slow Growth or Yellow Leaves: If a plant isn’t growing as fast as it should or if its leaves are turning yellow for no reason, it may have too many roots and needs a bigger pot.
• If your plant often falls over, it may be top-heavy because its roots are squished together. Up-potting can give the plant a bigger, more stable base.
• Look for Signs of Stress: If your plant wilts or acts stressed even after being watered, it could mean that its roots are squished together and needs to be re-potted.

These tips can help you figure out if a plant needs to be repotted, but it’s also important to learn about the specific needs of each type of plant you care for. Some plants prefer being root-bound, while others require regular up-potting to thrive.

Root-bound, meaning their roots fill up the entire pot and become quite dense. This condition can be stressful for many plants and stimulate blooming in others. Here are some examples: aloe vera, spider plants, African violets, African violets (Saintpaulias), peace lilies (Spathiphyllum), spider plants, and Boston ferns (Nephrolepis exaltata). These species thrive when their roots are crowded, producing more vibrant blooms and healthier growth. But even these plants will need to be repotted when their conditions get worse or when they get too big for their pots.

Up-potting can be done at very different times for different types of plants, depending on their needs and how fast they grow.

Fast-Growing Vegetable Plants: Plants that grow quickly, like tomatoes, cucumbers, and zucchini, need to be repotted more often, usually every two to three weeks. As they grow quickly, these plants tend to outgrow their containers rapidly and require more space and nutrients.

Up-potting also works well for vegetables like corn, carrots, radishes, spinach, and beans. You can start them from seeds right in the pot and then move them to bigger pots as they grow.

It is also known that lettuce, herbs, peppers, eggplant, squash, and radishes do well when grown in larger containers. This is especially true for gardeners who don’t have a lot of ground for a traditional garden.

Lastly, plants in the cabbage family, like cabbage, broccoli, cauliflower, and brussels sprouts, do better when planted a couple of inches deeper than they were in their original pots. This is called “up-potting.”

Slow-Growing Plants: Slow-growing plants, like succulents or bonsai trees, may only need to be up-potted every 1-2 years. These plants grow much slower and can handle being a bit root-bound.

Indoor Plants: Indoor plants must be up-potted every 12-18 months. However, this can vary based on the plants growth rate and the size of its current pot.

Perennial Plants: Perennials must often be up-potted every 2-3 years. These plants may get root-bound in their pots over time, and will benefit from the extra space and fresh soil that comes with up-potting.

Trees and Shrubs: Until they reach the size you want, small trees and shrubs usually need to be moved to a bigger pot every one to two years. Once they reach the right size, they can usually stay in the same pot as long as the top layer of soil is changed every year.

Orchids: Orchids generally need to be repotted every 1-2 years. Their ideal pot size is small, but you should change it if you see that the bark or moss is breaking down.

Remember, these are just general guidelines. Your plants needs may vary based on its species and overall health. Always research your specific plant type and monitor its health to determine the best up-potting schedule.

How to get seedlings with optimal root growth for transplanting.

The three best ways to achieve a healthy root system when growing your own plants from seed are:

• Use a bottom watering system to avoid compacting the soil.
• Plant in properly sized trays that encourage downward root growth.
• If you can’t move your seedlings yet, pot them up before their roots get too crowded.

Check out our Seed Starting 101 Guide on the Seed Starting Resource Blog to learn more about how to grow your own plants from seeds.

Successfully up-potting plants involves several crucial steps. Here are some practical tips and best practices:

Picking the Right Pot Size: The new pot should be just a bit bigger than the old one. If you go too big, the extra soil will hold more water than the roots can absorb, so you may end up watering too much. For small plants, choose a new pot that is 1-2 inches wider in diameter. For larger plants, choose one that is 2-4 inches wider.

Selecting the Right Soil: The type of soil you use plays a significant role in your plants health. Opt for a high-quality potting mix that suits your specific plants needs. For most plants, general-purpose potting soil works well. But some plants, like ferns and succulents, need a soil mix that holds more water, while others, like cacti and succulents, need a soil mix that drains quickly.

Tip: Always check the seed packet and the website of the seed provider for more information about the crop and variety to help your plant grow in every stage.

• When you water the plant, do it very lightly a few hours before you move it to a bigger pot. This will help the roots stay healthy.
• Take the Plant Out of Its Pot: Carefully move the plant out of its pot without hurting the roots. Press the sides and bottom of the pot to free the plant if it’s stuck. You can also use a popsicle stick or a Widger Dibbler Set to help you get the plants out.

Tip: If you water the soil a lot 12 to 24 hours before the transplant, it will stay together better while you pull out the cells.

• Prune the Roots: Examine the root ball. Cut off any roots that look dead or rotting.
• Get the New Pot Ready: Fill the new pot with potting mix and put the plant inside. The plant should be the same depth in this pot as it was in the last one. Put more soil around the plant and gently press it down to get rid of any air pockets.

Aftercare for transplanted plants:

• Fill the pot with water all the way to the roots. After repotting, water the plant well to help the soil settle around the roots.
• Rest: After repotting, put the plant somewhere quiet and shady for a few days to help it get over the shock of being moved.
• Watch the Plant: For a few days after repotting, keep an eye on your plant to see if it shows any signs of stress. Some wilting or leaf drop is normal, but symptoms that last for a long time could mean there is a problem.
• Care Again: Once the plant is comfortable in its new pot, you can go back to your normal care routine.

The Secret to Healthy Seedlings How to Transplant Them

FAQ

When should you transplant seedlings from seed tray?

How big should seedlings be before transplanting?

What is the best way to transplant a new seedling?

How do you transplant a plant from a seed tray?

Make sure the seedling is dropped in deep and inserted up to the leaves, which means you will get a healthier plant. Firm in the soil around the seedling so that the leaves are just above the surface. Repeat the previous steps as you work your way through the seed tray until you have transplanted enough seedlings for your own use.

How do you transplant a seedling?

When it’s time to transplant, wet your seedling tray soil & your garden’s soil. This makes the soil stickier. It holds together better when removing the seedling from the tray & when making a hole in the soil in your garden bed for the plant to go into. Gently push up from the bottom of the seed tray to pop the seedling out.

Should I Wet my seedling tray before transplanting?

Transplanting When it’s time to transplant, wet your seedling tray soil & your garden’s soil. This makes the soil stickier. It holds together better when removing the seedling from the tray & when making a hole in the soil in your garden bed for the plant to go into.

When should I transplant seedlings from seed trays?

Gardener’s gloved hands plant a sprout in the ground with garden shovel in early spring. Starting seedlings indoors gives you a jump-start, but determining when to transplant seedlings from seed trays will take knowing your plants. If out of season or just fragile by nature, nurturing seedlings to maturity can be a difficult feat.