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  • How to Transplant and Up Pot Seedlings

    April 03, 2024 15 min read 0 Comments

    Transplanting seedlings outdoors

    How up-potting can boost your garden's growth 

    Up-potting, or potting up, refers to moving a plant from a smaller to a larger pot. This is usually done to give the plant more room for its roots to grow and spread out, which can help improve its overall health and vigor.

    There are many reasons gardeners choose to up-pot their seedlings including: root development, nutrient availability, water Management, stability, plant health, introducing more room and nutrients, and extending your garden season for more yield.

    Whether you're an experienced gardener or a novice green thumb, this guide will equip you with valuable knowledge to ensure your plants thrive through successful up-potting.

    Understanding Up-Potting: The What and Why

    Gardeners often up-pot their plants in the spring or early summer, when most plants are entering a period of vigorous growth. When to up-pot can vary depending on the specific type of plant and its growth cycle.

    Up-potting is a vital part of maintaining and improving plant health for several reasons:

    1. Space for Root Growth: As a plant grows, its root system expands. A larger pot allows these roots to spread, preventing overcrowding and encouraging healthier growth.

    2. Nutrient Availability: Up-potting usually involves replacing the old soil with fresh, nutrient-rich soil. This gives the plant access to essential nutrients that support its growth and development.

    3. Improved Water Management: Larger pots hold more soil and more water. This can help maintain consistent soil moisture levels, preventing overwatering and underwatering.

    4. Prevents Root-Bound Plants: Their health suffers when plants become root-bound (their roots form a dense network that impedes their ability to absorb nutrients and water). Up-potting prevents this by providing ample space for roots to grow freely.

    5. Disease Prevention: Overcrowded plants are more susceptible to diseases and pests. Giving each plant enough space through up-potting can reduce these risks and promote healthier plants.

    6. Promotes Vigorous Growth: With more space, fresh nutrients, and optimal water management, plants can grow more vigorously, producing more foliage, flowers, or fruits.

    Remember, while up-potting offers numerous benefits, it's vital to do it correctly and at the right time to avoid causing stress or damage to the plants.

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

      Up-potting is beneficial to most plants, but it's especially important for those that are fast-growing or have expansive root systems. Here are some tips to help identify which plants might benefit from up-potting:

      1. Check the Pot Size: If your plant's size seems out of proportion with its pot, it might be time to up-pot. A general rule of thumb is that the height of the plant should be roughly equal to or less than the pot's diameter.

      2. Observe Root Growth: One of the most evident signs a plant needs up-potting is when roots start poking out of the drainage holes or appearing on the soil surface. This indicates that the plant has outgrown its pot and needs more room to expand.

      3. Monitor Watering Needs: If your plant needs watering more frequently than usual, it could mean that the plant's root system has filled the pot, leaving less soil to hold water.

      4. Watch for Stunted Growth or Yellow Leaves: If a plant isn't growing as quickly as it should, or if its leaves are turning yellow for no apparent reason, it may be root-bound and need a larger pot.

      5. Notice any Toppling Over If your plant tends to topple over; it could be top-heavy due to being root-bound. Up-potting can provide a larger, more stable base for the plant.

      6. Look for Signs of Stress: If your plant shows signs of stress, such as wilting, even after watering, it could indicate that it's root-bound and would benefit from up-potting.

      Remember, while these tips can help you identify when a plant might need up-potting, it's also important to research the specific needs of each type of plant in your care. 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. Examples of these include peace lilies (Spathiphyllum), spider plants (Chlorophytum comosum), African violets (Saintpaulias), aloe vera, snake plants (Sansevieria), and Boston ferns (Nephrolepis exaltata). These species thrive when their roots are crowded, producing more vibrant blooms and healthier growth. However, even these plants will eventually need repotting when their conditions deteriorate, or they outgrow their containers too much.

      The frequency of up-potting can vary greatly depending on the type of plant, its growth rate, and its specific needs.

      basil growing in 6 cells 

      Here are some general up potting guidelines for different kinds of plants:

      Fast-Growing Vegetable Plants: Fast-growing plants, such as tomatoes, cucumbers, or zucchini, often must be up-potted more frequently - typically every 2-3 weeks. As they grow quickly, these plants tend to outgrow their containers rapidly and require more space and nutrients.

      Other vegetable plants that benefit from up-potting include beans, corn, carrots, radishes, and spinach, which can be started from seeds directly in the container and then moved to larger pots as they grow.

      Lettuce, herbs, peppers, eggplant, squash, and radishes are also known to thrive when up-potted, especially for gardeners with limited ground space for a traditional garden.

      Finally, members of the cabbage family - including cabbage itself, broccoli, cauliflower, and brussels sprouts - can benefit from being planted a couple of inches deeper than they were in their original pots, which is a form of 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 plant's growth rate and the size of its current pot.

      Perennial Plants: Perennials must often be up-potted every 2-3 years. Over time, these plants can become root-bound in their containers and will benefit from the additional space and fresh soil that comes with up-potting.

      Trees and Shrubs: Small trees and shrubs typically need to be up-potted every 1-2 years until they reach your desired size. Once at the desired size, they can usually be maintained in the same pot by replacing the top layer of soil each year.

      Orchids: Orchids generally need to be repotted every 1-2 years. They prefer a tight fit, but it's time to repot if you notice the bark or moss breaking down.

      Remember, these are just general guidelines. Your plant's 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.

      When to transplant seedlings outside

      Transplanting tender seedlings outside is a regionally specific farm or garden task. In zones 8-11 you may be able to transplant seasonally appropriate plants all year round. For colder growing zones you may need to transplant your seedlings all at once in the late Spring once nighttime temperatures are reliably above 50℉. If you will be growing in a hoop house or cold frame you can move up your planting time by a number of weeks. 

      The best time to transplant any plant seedlings, whether it is one you have purchased from a local nursery or started yourself in seed starting trays, is once it has reached the proper stage of growth and outside conditions are appropriate. 

      basil roots in blue 6 cell tray


      Waiting until the seedling develops its second set of true leaves is one way to determine if a seedling is ready or not - but that is not always a hard and fast rule. Seedlings grown in cell trays need a sufficient root system in place before transplanting outdoors or into a cold frame. If the roots have not developed enough before you attempt to transplant outdoors, the root ball may fall apart when removed from the tray. This can break the fragile new roots and stunt the growth of your plants. 

      Having a strong root system is the best indication. You can check for proper optimal root growth by grasping one of your seedlings at the soil surface and gently pulling it from the tray. The entire plug should slide out of the cell tray. If the seedling is immature it will pull out and leave the majority of the potting soil behind in the tray. 

      If the seedling is overdeveloped it will come out easily but be root bound. Root binding happens when seedlings are left in plastic pots or trays for too long and the roots encircle the entire plug. Root bound seedlings are easy to identify because there will be numerous roots sticking out of the drainage holes and when you remove the plug you will see mostly roots with little growing media visible. 


      Avoiding root bound seedlings

      You can avoid root bound seedlings by using trays with air pruning slits. Our 6-cell trays and our 72-cell air prune trays are great to use when you aren’t sure exactly when you will be able to transplant your seedlings. The side slits prevent root circling and keep the seedling roots healthy over extended time periods.


      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. 
      • Pot up your seedlings before they become root bound if you cannot transplant them yet.

      For more information on growing your own plants from seed check out our Seed Starting 101 Guide in the Seed Starting Resource Blog

      basil in blue 6 cells up-potting into pink 3 inch seed starting pots

      Up-Potting Tips

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

      Choosing the Right Pot Size: The new pot should be just one size larger than the plant's current pot. Going too large can lead to overwatering, as the excess soil retains more water than the roots can absorb. Typically, choose a new pot that is 1-2 inches larger in diameter for small plants and 2-4 inches larger for bigger ones.

      Selecting the Right Soil: The type of soil you use plays a significant role in your plant's health. Opt for a high-quality potting mix that suits your specific plant's needs. For most plants, general-purpose potting soil works well. However, some plants, like succulents and cacti, need a well-draining soil mix, while others, like ferns, prefer a more moisture-retaining blend.

      Helpful tip: Always check the seed packet and seed provider’s website for additional crop and variety-specific information to help every aspect of your plant’s growth cycle.  

      Up-Potting Procedure:

      1. Water the Plant: Water the plant very lightly, a few hours before up-potting to reduce root stress.

      2. Remove the Plant: Gently guide the plant from its current pot, carefully not to damage the roots. If the plant is stuck, press the sides and bottom of the pot to free it, or use a popsicle stick or a Widger Dibbler Set to help pry the plants out.

      Helpful tip: Watering heavily 12-24 hours before transplant will help keep the soil intact while pulling out of the cells. 

      1. Prune the Roots: Examine the root ball. If you notice any dead or rotting roots, prune them off.

      2. Prepare the New Pot: Add some potting mix to the new pot and place the plant inside. The plant should sit at the same depth as in the previous pot. Fill around the plant with more soil, pressing gently to remove air pockets.
        basil up-potted into 3 inch pink pot

      Aftercare for transplanted plants:

      1. Water Thoroughly: After repotting, water the plant thoroughly to help the soil settle around the roots.
      2. Provide Rest: Keep the plant in a quiet, shaded area for a few days after repotting to help it recover from the shock of being moved.
      3. Monitor the Plant: Monitor your plant for a few days after repotting to check for signs of stress. Some wilting or leaf drop is normal, but prolonged symptoms could indicate a problem.
      4. Resume Care: Once the plant has settled into its new pot, resume your normal care routine.

      How do I choose the best seedlings at the nursery?

      When choosing seedlings from a nursery to transplant into your home garden there are a few things to look for to ensure you get the healthiest plant starts you can for a successful garden. You want big and healthy stems and leaves but not so big that the plant has overgrown its small pot and become root bound. 

      • Avoid leggy plants with tall thin stems. These have likely not been receiving direct sunlight and will possibly fall over when planted outside. 
      • Choose smaller, compact seedlings. They are ready to grow big once you plant them.
      • Check the foliage for discoloration and damage. Leaves should be uniformly green (unless it is a plant with variegated foliage). 
      • Look at the underside of the leaves to be sure there are no hitchhiking pests like aphids or insect eggs. 
      • Check the plants for signs of disease including yellowing of the leaves, brown spots and dried out tips. 
      • Look at the bottom drainage holes, a few visible roots are ok but if there are a lot sticking out through the holes it is probably root bound.
      • Look for moss or signs of fuzzy mold on the soil surface. These are likely signs that the seedlings are old stock or of overwatering both of which which can cause weak transplants. 
      • Squeeze the sides of the pot. It should give a little under pressure showing that there is still some loose potting soil, meaning the roots have a little space left to grow into.
      • Too little soil moisture is just as problematic as too much so make sure the potting mix is moist but not sopping wet. Root bound seedlings will often become hydrophobic and not take up water properly. 
      • Choose plants that have only leaves and possibly buds. Vegetables and fruits that have already begun to flower and fruit will stay small even if they are given more space. 


      Should I fertilize my seedlings before I plant them?

      Most seedlings will grow just fine without additional feeding. In fact, too much nutrition in the growing medium can cause seedlings to be weak or prevent seeds from germinating. Using a balanced potting mix that contains some aged  compost or worm castings will provide your plants with everything they need while they are small. 

      If you are using a sterile seed starting mix like ProMix that contains only coco coir, peat moss or perlite to germinate your seeds they may require a very light feeding once they have a second set of leaves. This only applies if you will be continuing to grow them indoors for a while beyond the second set of leaves. 

      We generally don't like to give direct advice about fertilizing as it is different for every individual and situation, but buying a well rounded potting soil will help to ensure that your seedlings are covered nutritionally. If you are planning on potting up things like tomatoes, peppers, cucumbers or squash and have started them in a sterile seed starting mix you can then pot up into a larger container with a balanced potting soil. This is more effective than using garden soil which may not have a balanced nutrient profile. 

      (Check out: The Easiest Way to Water Your Seedlings)



      The length of time a seedling can stay in a cell tray depends on the size of the cells. Deeper and larger cells both allow for extended growth as the plant has more room. Seedlings otherwise can become root-bound if not given adequate space for the roots.

      Typically, after sowing the seeds, the cell trays are used for around 3-4 weeks before transplanting occurs - whether it be to an outdoor plot or into a larger container. If transplanting tender seedlings outdoors, you may want to consider the use of a frost blanket to protect from late Spring frosts. Learn more about frost blanket in Frost Blanket: How to Use it and When.

      One thing to keep in mind with transplants, is to choose your sizing according to how long the transplant must stay indoors before getting transplanted into the garden. This will factor into Selecting the Right Cell Tray for the seed types you will be growing. 

      transplanting seedlings


      Farmers have moved into using cell trays in order to increase the amount of transplants that can be grown in a smaller space. Many have their own tips and tricks to finessing a seedling plug out of a cell or using a plug popper. Bootstrap Farmer cell trays are specially designed for growers by growers to make this chore a bit easier.  Here's a great video highlighting how to remove the plugs from the cell trays.

      Transplanting Seedlings Outdoors

      The process for potting up and transplanting seedlings outdoors are very similar. Start by hardening off properly if you are planting outside, for more info on this process you can review our Seed Starting 101 Guide. If your plants will be continuing inside you can skip this step.  

      My mother taught me the Slap and Tickle method of transplanting when I was little, and it is still the best way I have found. Once your pot has soil in it and is ready to go, make a hole about the size of your transplant. If your seedlings are in small pots to remove the plant, start by lightly slapping each side of the pot.

      Next, turn the plant upside down while holding the main stem between your fingers and the majority soil surface on your palm. Slap the bottom of the pot a few times until the root mass comes loose and the plant is resting in your hand. Tickle the roots apart a little if they have become root-bound. This action helps the plant to root more successfully in its new container. Place into the larger ground and lightly firm the soil. Water well and protect from the elements until established.

      If your plants are in cell trays the process is similar except for the removal from the trays. If in a tray with a large enough hole press the seedling up from the bottom. If not large enough, use a butter knife or dibbler to loosen the sides and pry the plant up. Then follow the same process outlined above. 

      Why plant seedlings over direct sowing seeds in the garden? 

      Sowing seeds into cell trays and planting starts into the ground offer some major advantages to the grower. You will be able to get a head start on the growing season by starting weeks before your last frost date. Planting into cell trays also helps increase the number of seedlings that can be grown in a smaller amount of space. This is a huge advantage for growers who are growing for quantity.  

      Another advantage of growing out seedlings to transplant is a higher seed success rate. You only transplant strong seedlings, therefore generally are able to have more growing success. Want to learn more about the process of starting your very own seedlings this season? Read Seed Starting 101 for everything you need to know about starting vegetables, flowers, and herbs from seed for your garden. 

      Size Comparison Image of 2.5" Seed Pot, 3.3" Pot, 5" Pot, 6 cell and 4 cell inserts

      Bootstrap Farmer Up-Potting Equipment Options:

      The Foundation: 1020 & 1010 Trays: Propagation trays for hobby or commercial growers are USA-made heavy-duty, making them easier to carry and move around. 

      Seed Starting Options: Bootstrap Farmer offers a complete lineup of options for gardeners based on industry-standard and Bootstrap Farmer innovations designed for farmers making a living from feeding their communities who need to depend on the equipment they invest in. All options are compatible with our 1020 & 1010 foundational trays and will move your seeds from first germination to field transplanting season after season. 

      Cell Trays: A cell tray insert is a plastic container with multiple individual compartments, each acting as a mini pot. These are typically used in seed starting and are designed to fit into Bootstrap Farmer 1020 trays. One of the key advantages of using cell trays is the efficient use of space. They allow gardeners to start many seeds within a small area, which is particularly beneficial for those with limited room. Furthermore, because each seedling is grown in its own cell, there is less disturbance to the roots when it's time to transplant. This reduces the risk of damaging the delicate seedlings during this crucial stage.

      Additionally, having separate cells for each seed prevents overcrowding, which can lead to disease and poor growth. It also makes monitoring and managing each seedling's water, soil, and growth progress easier. Lastly, cell trays are reusable, providing a cost-effective solution for gardeners who regularly start seeds. Therefore, if you're considering starting seeds, a cell tray insert can be an invaluable tool to help ensure your seedlings enjoy the best possible start.

      Bootstrap Farmer offers cell trays in 50, 72, 128, and 200-count cells. 

      Check out this article to learn more about Bootstrap Farmer cell trays and their use.

      Air Prune Trays: An air prune tray for seed starting is a specially designed tray that encourages the development of a robust, fibrous root system in plants. The concept behind air pruning is that when a plant's root comes into contact with air at the edge of the potting medium, it naturally prunes itself and stops growing lengthwise. Instead, the plant focuses on producing new, lateral roots within the soil.

      These trays often have open bottoms that expose the roots to air, triggering air-pruning. This design prevents the roots from circling the inside of the pot or becoming root-bound, which is a common problem in traditional pots.

      Air prune trays promote healthier root development, leading to stronger, more vigorous plants. They are beneficial for seed starting as they help establish a robust root system early, setting the stage for successful plant growth.

      Bootstrap Farmer offers 72-count trays, which are available in 6 colors. Black, orange, green, pink, blue, purple.

      6-Cell Air Prune Trays: Our 6-cell tray inserts are made for the grower who wants an easily removable insert when growing various crops. These are not cheap seed tray inserts.  They are built to be used for many years of use on farms. Available in our six Bootstrap Farmer colors, plus an additional five-color collection from Jill Ragan’s Whispering Willow 6-Cell Collection.

      2.5” Pots: Our smallest pot is a Gardner favorite, available in multi-color packs, black - or new this season, clear. Additional colors are available from Whispering Willow 

      They fit in our 32-cell plug trays, making planting your favorite vegetables, herbs, or flowers easier.

      3.3” Pots: designed with the serious grower in mind., Eighteen of these pots are designed to fit in a 1020-deep tray (not included). Also available in sets with inserts and in multi-color. 

      4-Cell Air Prune Inserts: Need more options? Bootstrap Farmer larger 4-cell plug inserts are deeper for growing varieties of crops that need a little more room. Eight of these removable inserts fit in a Bootstrap Farmer 1020 tray. Made out of food-safe, heavy-duty polypropylene plastic and built to last many seasons. Color code your seedlings in these insert plug trays.

      Available in black, blue, green, purple, pink, orange, and multi-color packs.

      5-inch Seedling Pots: Designed with vegetable and flower gardeners in mind, these durable 5" pots are perfect for up-potting tender seedlings to plants already bearing fruit and flowers, giving northern growers more. Also available in sets with inserts in multi-color options.


      Be sure to share your seed starting successes with us on Instagram and tag us with questions you have about the process. 


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