Seed Starting Tips for Growing Your Own Transplants

An article by Travis Key from Lazy Dog Farm

Our previous blog provided a comprehensive list of the vegetables that perform better when transplanted versus the vegetables that should be direct-seeded in your backyard garden. On this blog, I wanted to discuss some basic tips for seed starting and growing your own transplants. Seed starting is a skill that you probably won’t master the first time you try it. But once you get the hang of it, it’s like riding a bike.

The Best Soil for Starting Seeds 

Many beginner gardeners make the mistake of using a “potting mix” to grow their vegetable transplants. Potting mixes tend to be relatively chunky with pieces of bark or sticks in it. The consistently of these mixes can make it difficult for your seedlings to form a solid root ball prior to transplanting.

We recommend using a “seed starting mix” that is specifically designed for growing transplants. These mixes are much finer than potting mixes and usually include peat, vermiculite, and perlite. They hold water well but also drain well. They also help the seedling form a nice root ball inside its container.

There are many seed starting mixes on the market, but we particularly like ProMix or Sunshine #4 mix. Both have performed well for us over the years. Seed starting mixes like these are sterile, so you don’t have to worry about soil-borne diseases plaguing your seedlings.

Seed starting mixes are relatively dry out the bag. They will need to be moistened before planting your seeds, and this usually takes a good bit of water. Some gardeners will pre-moisten their seed starting mix in a large tub before filling their seed starting cups or trays. You can also fill your cups or trays with the dry seed starting mix and water it 3-4 times before planting.

Choosing Containers for Seed Starting 

One of the biggest misconceptions about seed starting is that a bigger plant is better than a smaller plant. If you visit the plant aisle at your local big box store, you’ll often find large, potted tomato plants being sold for a premium. But bigger isn’t always better when it comes to transplants.

The larger the transplant, the longer the “transplant shock” time. When you put a tomato plant into the ground, it will take some time for it to start spreading its roots into the new soil. The larger the transplant, the longer this takes. Those larger plants are so used to wrapping their roots around each other in that pot, the new soil is foreign to them.

As a result, smaller transplants will often start growing much faster and outpace the larger transplants. Most of our vegetable transplants only have a 1-2” wide plug, and they do great! You don’t need a huge plant to be successful in your backyard garden.

The other downside to using larger pots is the volume of seed starting mix required to fill those pots. Smaller cell seed trays will allow you to grow more plants and use less seed starting mix per plant. If you grow all your tomato plants in large cups, you’re going to be using significantly more soil.

Warming Your Soil with Heat Mats 

Unless you keep your house thermostat at 80 degrees, you’re probably going to need a heat mat to grow your own seedlings. This is especially the case for hot peppers which need warmer soil temperatures for ideal germination. But tomatoes also will germinate much better in soil temps around 85 degrees.

There are a variety of heat mat sizes and styles on the market. If you’re growing your seedlings indoors, a lighter grade heat mat will probably suffice. If you’re growing seedlings in a greenhouse or another outdoor area, you’ll probably want a heavy-duty heat mat that can handle the elements.

Keep in mind that even the best heat mats will only raise the ambient temperature 10 degrees or so. If the temperature in your greenhouse or seed starting room is in the 50s or 60s, a heat mat won’t help much. The heat mat is designed to give you a small boost in temperature and keep that temperature consistent so seeds can germinate.

I highly recommend getting a thermostat with your heat mat. Without a thermostat, the heat mat will run “wide open” and can get too hot in some cases. Soil temperatures close to 95 degrees can inhibit germination. A thermostat allows you to dial back the heat mat so that it doesn’t get quite so hot.

Light Setups for Seed Starting 

If you’re growing seedlings in a greenhouse, you don’t have to worry about grow lights. But if you’re growing indoors, you’ll need grow lights. Without grow lights, plants will start to reach for the ceiling lights and become “leggy.” The stem of the plant won’t be thick enough to support the fast vertical growth and plants will start to fall onto the soil.

As is the case with heat mats, there are many different options for grow lights. Some gardeners have success using bright, LED shop lights while other swear by more expensive grow light systems that are specifically designed for indoor growing. Either way, you’ll want a way to raise and lower the lights above the plants. As plants grow, you’ll want to raise the lights so that they don’t burn the plants.

Fertilizing Seedlings for Healthy Growth

Once seedlings emerge from the soil and have their second set of leaves (also known as “true leaves”), you’ll want to start fertilizing them with a low dosage of fertilizer. We like to inject AgroThrive General Purpose fertilizer each time we water our seedlings through a process we call “micro-dosing.” You can read more about that technique here.

Fertilizing the seedlings will help them form a strong root system and stem so that they perform better when transplanted. Weak seedlings usually don’t grow well once transplanted. But a strong seedling can produce bountiful harvests for you and your family.

Thousands of gardeners have been tuning in to The Lazy Dog Farm YouTube channel where Travis covers a variety topics ranging from how to successfully start seedlings to how to make a flavorful hotsauce that packs a punch. Accompanied by his wife Brooklyn and their two boys, the gardens on their 2 acre homestead in southwest Georgia are always filled with a wide variety of vegetables that are enjoyed fresh or preserved for later.