Transplanting Seedlings Outdoors, What You Need to Know

The time has come to move your seedlings outdoors!! Transplanting seedlings outdoors into your garden is an exciting step in your gardening Adventure. However, it is more challenging than just grabbing all your plants from indoors and dropping them in the ground in your new garden. Moving your seedlings Outdoors can be tricky, and if not done correctly, can lead to damage or death of your young seedling. There is no worse feeling than coming outside and seeing your hard work for the last several weeks wiped out from the shock of moving outdoors. This article will walk you through some tips to ensure this does not happen to you when transplanting seedlings outdoors.

What is Transplanting Seedlings?

Transplanting seedling or small plants is the process of moving the plants from one location (typically a pot or container) to an outdoor garden where they can continue to grow and produce. Seedlings are young plants, such as those purchased as small plants/seedlings from a local nursery or those grown from seeds at home. Typically, these young plants are started in small containers and require transitioning or transplanting to your outdoor garden before outgrowing their containers. 

When to Transplant Seedlings Outdoors in the Garden

Timing is the first thing to consider when transplanting seedlings outdoors and is critical to ensure your plans have a good head start to the growing season. The specific time to transplant seedlings outdoors depends on your particular climate and the plant you are transplanting. Most warm-weather vegetables started indoors are frost sensitive and can be damaged severely, planted too early, and exposed to a frosty night. So don’t rush it; take your time, and research your planting zone and specific plant in advance. I recommend checking USDA Plant Hardiness Zone Map or the Almanac website to find the last expected frost for your area. 

In addition, the soil’s temperature should be considered before transplanting warm-weather plants such as tomatoes, peppers, or eggplants. Typically, in warm weather, plants prefer a soil temperature greater than 60 degrees Fahrenheit; they can survive in cooler soil, but their growth could be stunted. For more information on warm weather planting, reference this article or more details on some of the more popular summer vegetables.

cool weather plans such as peas, lettuce, and spinach can be transplanted Outdoors earlier, in cooler soil, and tend to be more frost resistant. 

With that in mind, in this article, we will go into more detail on the general process of transplanting seedlings that are started indoors and are now being moved into your outdoor garden. 

How to Transplant Seedlings Outdoors in the Garden

So now you know when to transplant or see things outdoors based on your climate and the specific plant requirements; now what?

Step 1: Prepare the Soil

Prep your garden to make it amenable to growing your vegetables. Loosen the soil and consider adding compost or other organic material to improve the fertility of your soil. Once you have loosened your soil, try to avoid walking on it, compacting it again.

Increase the temperature of your soil by spreading black plastic or landscaping fabric across the ground you want to plant several weeks before planting. The black fabric will help absorb the heat from the sun and warm the soil. You can reference My article on preparing your Garden in Spring for more information.

Step 2: Harden off your Seedlings

Before planting your seedlings in the ground, hardening off the seedlings is essential. Hardening off slowly exposes them to the outdoor elements, starting with an hour to the first day and gradually increasing the time spent outdoors over 7-10 days before placing them in your garden soil. 

The slow exposure will toughen them up to the outdoor conditions, limiting the shock to the plant, as they have only been exposed to a temperature-regulated, light-regulated, and aerated environment in your indoor greenhouse or seed starting kit.

Step 3: Water your Seedlings

Just prior to transplanting seedlings, water your seedlings thoroughly. Watering will help them prepare for the shock of being transplanted outdoors.

Step 4: Dig a Hole

though this is straightforward, remember to dig your hole larger than the root ball of your seedling. I typically dig a hole slightly larger than the container that my seedling is currently in, giving it a little room to spare. The depth of your hole should be about the same depth as your seedling container. So before taking your seedling out of its container, ensure the container can fit nicely in the hole you have made.

Step 5: Remove the Seedling from its Container

Gently remove the seedling from its container, careful not to damage the roots. This can be tricky as the soil can be stuck to the container wall, or the roots can grow through the drainage holes. You can gently squeeze the container size to loosen the soil from the side walls, tip the container upside down with your hand covering the opening, and then slowly shake the container so the soil and root ball falls out of the container into your waiting hand. You can also use a butter knife to loosen the soil and gently pry the soil and roots out of the container.

Step 6: Place the Seedling in the Hole

Now place the seedling in your dug hole. You can gently roughen up the outside of your root ball to encourage root growth, but make sure not to rip and break off roots. Ensure the top of the root ball is level with the top of the soil. You don’t want a root ball exposed above the ground level, exposing it to drying out, and you don’t want to bury more of the stem in the soil as this can lead to increased diseases/rot of the plant. Add soil around the root ball, then gently press down around the plant to remove air pockets and Ensure good soil contact with the roots.

Step 7: Water the Seedling

Water immediately after transplanting seedlings. Watering will help the soil settle around the roots. Water deeply to ensure water gets to the lowest levels of the root ball. Be careful not to overwater, as this can lead to root rot. Instead, water until the soil is saturated with just a little bit of accumulating water, then stop and allow that water to drain into the soil.

Step 8: Add Mulch

Mulching is not required, but a layer of mulch around the base of the plant can help retain moisture, suppress weeds, and regulate soil temperature. Great options for mulch include strawberries and then dried grass clippings.

Tips for Successful Transplanting Seedling  

  1. Harden off Before Transplanting Seedlings: DO NOT skip this step. It’s a mistake you only make once, but learn from your mistakes and take the time to harden off your plants. Hardening off gradually exposes seedlings to outdoor conditions, such as sun, wind, and cooler temperatures. This process helps the plants adjust to the outdoor environment and reduces transplant shock. You can start hardening off seedlings about a week to 10 days before transplanting by placing them outside for a few hours each day and gradually increasing the amount of time they spend outdoors.
  2. Plant Seedlings in the Evening: Planting in the evening or on a cloudy day can help prevent transplant shock. Planting at this time helps due to the cooler temperatures and reduced sun exposure, which can help reduce plant stress.
  3. Water Seedlings Regularly: After transplanting seedlings, it is essential to water your seedlings regularly, especially during the first few weeks. 
  4. Fertilize Seedlings Appropriately: Fertilizing them as directed can help them establish strong roots and grow healthy and strong. Use a starter fertilizer, which provides phosphorus, to promote strong root development. However, be careful not to over-fertilize, as this can burn the roots and damage the plants.

Transplanting seedling gets your young plants out of your house and into your outdoor garden. These plants can be purchased from a local nursery or seedlings you started in your home. An important step that, when done correctly, sets you up for a summer of gardening bliss. Done incorrectly can be devastating. This step-wise process will help you successfully plant your seedlings in your garden and minimize the stress and shock to the plant. With proper care and attention, your seedlings will grow into strong and healthy plants that will provide you with a bountiful harvest.

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