Grow Your Own Transplants

By Skip Richter, Contributing Editor

If you’ve never tried growing your own transplants, you are missing out on a wonderful part of gardening.

I have nothing against purchasing transplants and in fact do so every year. But I also grow some transplants of my own for a number of reasons.

First of all, growing my own transplants gives me a head start on the gardening season. While it may be too early to be out in the garden planting warm-season vegetables and flowers, it is not too early to be starting the spring garden indoors.

I also like to plant tomatoes that are quite large and even have their first blooms on them. Such plants are usually not available in the garden center, but I can grow my own by starting early and bumping them up into 4-inch, 6-inch and even 1-gallon containers as they grow.

Starting your own transplants allows you to have the latest, greatest new cultivars that are not yet available in your local garden centers. Some of the best cultivars never make it into the retail trade as transplants.

Growing your own plants also allows you to grow a family favorite (such as fragrant petunias from grandma’s garden or an heirloom such as ‘Crawford’ lettuce) that may not be available locally.

Perhaps you’d like to collect and grow seeds from a wild plant, such as some unusually colored Mexican hats that you found on the roadside or a native tree that’s not available in the trade.

Last but not least, growing transplants is just plain fun! I love the satisfaction that comes from raising my own plants. It is also great winter therapy to plant seeds! Watching them emerge and cultivating the start of next season’s garden is so rewarding.

Every gardener knows that dreams of a gardening Eden often take an unfortunate turn; or with apologies to poet Robert Burns, “The best-laid plans of gardens and men often go awry.”

In order to help those winter visions of a bountiful summer harvest of flowers and vegetables come to fruition, some basic tips for success with growing your own transplants are in order.

Timing

Genetic factors, temperature and light levels affect how fast a vegetable or flower species grows.

Under good conditions, squash, cucumber and melon transplants take two to three weeks, cole crops and tomatoes take five to seven weeks, and peppers and eggplant take seven to weight weeks. Many flowering bedding plants take five to eight weeks, but some like marigolds and zinnias take only three to four weeks weeks, while pansies take 10 to12 weeks.

Determine the date to start seeds indoors by counting back from when you plan on setting the plants out in the garden.

Growing medium

Tender seedlings are susceptible to root and stem-rotting diseases. The conditions that favor seedling growth also favor disease development. Therefore, it’s important to avoid garden soil and use only use a fresh, disease-free, soilless growing medium.

For larger seeds, a potting-soil mix may do, but when planting small seeds, a fine-textured, seed-starting medium is best, as it allows more exact planting depths and better growing-medium contact with the seed for successful germination.

Growing containers

You can grow transplants in about any container that drains well and holds an adequate amount of medium to support the developing seedling. If you select previously used containers, dip them in a 10 percent bleach solution to kill any fungi or bacteria they may be harboring.

There are “store bought” options for growing transplants, such as special trays with individual chambers and a clear dome lid. If you want to save a few bucks, you can use Dixie cups or Styrofoam coffee cups with a few holes punched in the bottom for drainage.

I prefer homemade newspaper pots. Choose a small cylinder about 1-1/2 to 2-inches in diameter, such as a frozen orange-juice can or narrow plastic bottle.

Tear strips of newspaper wide enough to create the desired container depth but also fold under to form a bottom. Roll the newspaper around the container. Fold the paper over the bottom and slide the newly formed paper pot off of the container. Fill the paper pots with soilless media and stack them side-by-side inside in a tray that holds water. Place water in the tray and it will “wick” up into the paper and growing mix. This makes it easy to water and to keep the soilless media moist.

Planting depth

Plant seed at the depth indicated on the seed packet. As a general guide, plant seeds about three to four times as deep as the seed is wide. Gently firm the pre-moistened soilless media around the seed and then mist the surface to wet the surface without dislodging the seeds.

Some seeds, including lettuce, petunia, coleus, alyssum and nicotiana, germinate best when exposed to light. Sprinkle them on the surface of pre-moistened seed-starting mix and gently press them against the surface. Adding a very light dusting of vermiculite over the surface can help keep the seeds moist while still allowing light to reach them.

Temperature

As a general guide, 70-75 degrees is a good temperature for many types of seeds. However each species has its optimal growing range, and as you move away from that range (especially cooler), germination slows considerably.

A window can be a pretty cool spot during the winter as can outdoors in an unheated greenhouse or cold frame. There are special seed-starting mats that have a thermostat to keep them at the desired temperature. Even if the air temperature is cooler, these mats can warm the soilless media where the seed is germinating.

Moisture

When the seed imbibes water, a chain of biochemical reactions is initiated that marks the beginning of the germination process. Once initiated, if the seedling dries out at any point in the process before it is able to get a root down into moist soil, it will die.

One way to help prevent drying, especially with seeds planted at or near the surface, is to place the moistened seed tray in a clear plastic bag, such as a dry cleaner’s bag.

Just fold the bag under to hold in moisture and check it daily. When the seeds start to germinate, open the bag a bit to let in air, and remove it once the seeds have sprouted. Place a few plant labels in the tray to keep the plastic from laying on the soil and the sprouting seedlings.

Light

This is the big one! The most common mistake gardeners make in growing transplants is not providing adequate lighting. Even in a bright window, light levels can be less than ideal. If seedlings do not get adequate light, they develop spindly growth in search of light.

If you are growing your seedlings indoors, provide a bright light very close to the plants. I use two 4-foot shop lights with two florescent bulbs each — one cool white and one warm white to expand the wavelength spectrum a little.

The florescent bulbs don’t get hot and can be suspended a few inches above the seedlings. It may seem that there is little difference between a light being a foot away from the plants and it being a few inches away, but there is a big difference in the amount of light reaching the leaves. Purchase a timer that plugs into the wall outlet and run the light for 14 to 16 hours a day.

After-planting care

Don’t forget to label the containers with the species and cultivars. You can purchase labels or make them out of cut sections of plastic window blinds. Use a pencil to write on the labels, as it won’t wash off or fade in the sunlight.

Once seedlings are up, make sure to water as needed to maintain moist growing media, but don’t keep the soil soggy wet or else the plants will suffer. Fertilize with a diluted liquid plant food at the lowest label rate after the first true leaves appear, and weekly thereafter. Don’t overdo the fertilizing, as extra nitrogen along with warm temperature and less-than-ideal lighting can promote lanky growth.

Seedlings growing in still air tend to develop weak stems. Brush over them once a day with your hand or a pencil to move them around a bit. This movement signals the seedling to develop a stockier stem.

If the weather is mild, move your growing transplants outdoors during the mid-to late-day period (when temperatures are the warmest) to provide them more light and to grow a bit more to promote development of a stronger plant.

When it’s time to transplant them outdoors, take a week or so to gradually leave them out for longer periods, extending into the cooler times of the day. It is a shock to a transplant that has been living the life of Riley indoors to suddenly find itself plopped into the garden where nighttime temperatures are still quite cold!

These tips should help you get off to a good start growing a few transplants of your own this season. So take the plunge and give it a try!

As with any new gardening activity, there is a learning curve. Experiment a little and have fun in the process! If you already grow your own transplants and have some creative ways that have worked well for you, we’d love to hear about them at Texas Gardener.