I credit most of my garden’s success to my transplants. Starting seeds ahead of time has a lot of advantages, and transplanting seedlings helps a garden grow sooner while also saving money.

Of course, this all depends on the seedlings thriving. Weak seedlings mean weak transplants, which ultimately means that the plants fail to thrive once they are out in the garden. This is why boosting seedling growth for transplanting is a vital part of any gardening plan.

Why Use Transplants?

Healthy transplants tend to perform significantly better in the field than seeds for several reasons. They can be started indoors earlier, giving you vegetables or blooms sooner. They are better equipped to handle weed competition and pests and are easier to weed around. And, on a practical level, transplants allow you to plan and plant more efficiently, as you do not have to worry about germination rates in the field, and you can avoid some of the risks associated with late frosts.

What Makes a Healthy Transplant?

So how do you know what a healthy transplant looks like? First of all, they have strong root systems, forming a solid ball that is not root bound or underdeveloped. Their stems are also strong and straight, not spindly, weak, or diseased. Their leaves are the appropriate color for their variety and show no symptoms of wilt, discoloration, or pest damage as well.

Fortunately, getting your transplants to meet these criteria is actually quite simple.

Discard Unhealthy Transplants

Wilting seedling

Any transplants that do show evidence of pest damage or disease should be discarded. Weak plants are more susceptible to accruing more damage, diseases, and pest problems, and if your transplant is not thriving in the tray, chances are, it will not thrive in the field. Even worse, they could attract pests and diseases to otherwise healthy plants, wiping them out too.

Start with Good Potting Mix

Start your seedlings off with a good potting mix. I like to begin with a sterile material for germination, and then I transition the seedlings to a richer, more fertilized mix as they grow. Your preferences may be different from mine, but no matter what you use, always make sure that your compost is properly aged and reaches the appropriate temperature to kill weed seeds and diseases before using. If you are not comfortable making your own potting mix, purchase a bagged variety from your local gardening store.

Pot Up Your Seedlings as They Grow

Most seedlings benefit from potting up, especially tomatoes, peppers, eggplants, tomatillos, and vegetables in the brassica family like broccoli, kale, and cauliflower. This term means transitioning your plant to a larger pot with more soil as it grows. As you do this “mini-transplant,” make sure you bury the plant up to its growth point, which is place on the plant where it is putting out new growth. Some seedlings have higher growth points than others. This process helps your plant put out a stronger root system, making them more stable when you finally transplant them into the garden.

Watch Out for Warning Signs

A lot of things can go wrong with your transplants if you start them from seed. One of the biggest problems is light deficiency. Unless you live by the equator, you will probably need to supplement light during the darker spring months. Signs of light deficiency in your plants include long, spindly stems. These leggy seedlings are prone to falling over, which creates problems down the line.

Watering seedling

Overwatering seedlings can lead to damping off. This disease is common in greenhouses and causes seedlings to wilt and die. The best way to prevent this is to obviously avoid overwatering and make sure there is good air circulation in your greenhouse or growing area.

Harden Off Your Seedlings

You can’t expect your seedlings to thrive without helping them acclimate to the outdoors. Hardening off is a process that allows your seedlings to adjust to natural light and weather in small doses. Once your seedlings are almost large enough to transplant, place them outside for a few hours each day. Watch your weather for any problematic conditions like storms and keep your transplants inside if something bad is coming.

Fish Emulsion Immersion

Transplanting itself is stressful for plants. They are removed from their pots and placed in foreign soil, where oftentimes conditions are less than ideal. You can help these transplants thrive after being moved by dipping or soaking them with a liquid fertilizer like fish emulsion. While admittedly odoriferous, fish emulsion gives your transplants a nutrient boost that helps them establish themselves in their new home. All you have to do is mix the concentrate with the appropriate amount of water, dunk the roots of the seedlings—most gardeners just dunk the seedling tray, leaving the leaves and stem above water—and then put them in the ground.

Pack Your Plants a Snack

plant food jar

Fish emulsion gives your plants a nutrient boost, but what about a snack for later? Mixing a little plant food, like crab meal, in the soil where the transplant's final location will be provides it with the energy necessary to get a jump start on growth. This will also keep your plants healthy, helping them out-compete weeds and avoid pests.

These tips won’t guarantee that your transplants thrive, but they will help you avoid some of the common problems that gardeners face with their seedlings.