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Natural Awakenings Tucson

Growing Garden Transplants

Jun 30, 2021 11:00AM ● By Thrive and Grow Gardens
Selecting seed and growing our own transplants to harvest can be one of the most rewarding feelings in gardening. When we sprout a seed and grow it all the way to harvest, we are empowered in knowing the major steps to growing our own food.

Use this overview of the steps required to turn a seed, some soil and a container into a living, breathing organism—a vegetable transplant.

1. Choose seeds.

The first step in growing transplants is to select what kind of transplant to grow. Find an accurate local planting calendar (online or at local plant nurseries). A planting calendar shows what seeds should be started depending on the season. If keeping the plant indoors for its whole life, no planting calendar is needed.
If planning to collect seeds from plants when they mature, buy seed that has been open-pollinated. These seeds have been carefully bred to give offspring that will resemble the parent plants. Otherwise, for the most uniform, predictable crops on the market, look for hybrid seeds, or “F1 seeds”. Seed collected from hybrid plants can give wildly variant offspring or even be sterile.
Choose a variety. Plant breeders have put a lot of time and energy into giving us varieties of plants that can do very well in our individual environment. Growing in containers? Growing in an extremely hot or cold environment? There are seeds that can fit all needs.

Pro-tip: Some seeds don’t do very well as transplants. These plants grow best when they are seeded directly into the ground: carrot, parsnip, turnip, radish, peas and beans.

2. Choose soil.

The transplant’s soil is its home for up to eight weeks, so be sure to give it everything it’ll need. Soil should be fine, uniform and aerated (fluffy). A soil mix is fine, but make sure it doesn’t have large chunks of wood or rock that could hinder the seed’s growth. Soil should also have some slow-release nutrients available. Good, finished compost or vermicompost is a great recommendation. Try buying organic soil and mixing ⅔ soil with ⅓ compost when filling containers.
Don’t try to save money by mixing in native dirt to the soil mix; it is too heavy and will cause too much compaction, leading to seeds that can’t breathe.

3. Choose container(s).

If using the right soil, most vegetable transplants will be perfectly happy in a 2”x2”x2” container. For those new to growing transplants, try using 606 trays. These trays are similar in size to most six-packs available at local nurseries, so reduce and reuse if possible.
Using a larger container won’t hurt anything—other than our wallet. Using pots that are four or five times the recommended size leads to a much larger soil bill, not to mention the extra space that is required to grow the same amount of transplants. The only added benefit of using a larger container is that there is no need to up-pot the long-lived transplants like tomatoes and peppers.

4. Sow seeds.

Spread out and mix soil well; this prevents any uneven distribution of materials. While mixing, moisten the soil to the consistency of a well wrung-out sponge.
  •  Fill containers with soil.
  •  “Drop” the containers from about six inches high to remove any large air pockets.
  •  Create a half-inch divot in the center of each container.
  •  Drop a seed in each divot.
  •  Mark each container with some kind of deviation to remember what each tray is and the date sown.
  •  Finish filling the containers with soil.
  •  Water the containers with a gentle spray of water two or three times to ensure it is wet enough. If the soil starts puddling, stop watering and give it time to soak up the water.
  •  Place containers in an area that has the seed’s desired germination temperature.
  • Keep the soil moist, but don’t overwater.

5. Caring for a newly emerged transplant.

When the seeds have emerged, it’s very important that they get enough light, water and are in their desired temperature range.
Light: If growing indoors under grow lights, be sure to run the lights for 12 to 16 hours per day. For best results, use lights that have a Kelvin value between 4100-6000K and a lumen between 2000-3000.
Water: Keep the soil the same moisture as a well wrung-out sponge. Not too wet, not too dry. Don’t use extremely cold water on the transplants as it can slow their growth. Lukewarm water is best.
Temperature: The seeds will grow best if they stay in the same temperature range in which they sprouted.

6. Planting.

Transplants are ready to plant when they are desired size and have white, lightly circling roots and green, full leaves. Don’t wait until the leaves begin to turn yellow or the roots are heavily circling.
Before planting, harden-off transplants for three to five days by placing their container outside for increased time each day. For example, two hours outside the first day, four hours outside the second day, and so on.

For a guide on how to properly transplant, see

Thrive and Grow Gardens is a local vegetable gardening educator and raised bed design and build company, located in Tucson. Connect at 520-305-3127 or See ad, page 11.

Michael Ismail

Thrive and Grow Gardens - 3755 E 34th St 113, Tucson, AZ

Thrive and Grow Gardens designs and helps maintain backyard vegetable gardens with our products and services, which include raised garden beds, compost systems, potato boxes, irrigation o... Read More » 

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