Moving young plants from a protected environment into the garden is a common practice that bypasses the challenges of direct seeding. These young plants, often called transplants or starter plants, offer gardeners a significant advantage by giving them a head start on the growing season. Using starter plants helps ensure higher success rates and earlier harvests compared to sowing seeds directly into the garden soil.
What Defines a Starter Plant
A starter plant is a young specimen, typically grown from a seed or a cutting, cultivated in a controlled setting like a greenhouse or indoor grow room. These environments provide optimal conditions for germination and early growth, shielding delicate seedlings from harsh outdoor variability. The primary function of a starter plant is to bypass the most vulnerable stages of a plant’s life cycle, offering a robust specimen ready for the garden.
Starter plants possess an established root system and have developed their first set of true leaves, which are distinct from the initial cotyledon leaves. A plant is generally considered ready for the garden when it reaches an age of approximately four to eight weeks, depending on the species. At this stage, the young plant has sufficient photosynthetic capacity and structural integrity to handle the transition to the garden bed.
Common Starter Plant Formats
Starter plants are presented in several common commercial formats, each designed for different scales of gardening and plant types.
One common format is the plug, which consists of small, individual soil or media blocks holding the seedling’s root system together. Plugs are useful for mass planting because they are easily separated and cause minimal root disturbance during removal.
Another frequent presentation is the multi-pack tray, often seen as six-packs or four-packs of conjoined plastic cells. These trays allow for high-density transport and are a favorite for annual flowers and vegetables like tomatoes or peppers. Roots in multi-packs can sometimes become intertwined, requiring careful separation before planting.
Larger, more established plants are typically sold in individual container pots, commonly three to four inches in diameter. Plants in this format have a more developed root system and greater soil volume, providing a buffer against transplant shock. These containers are preferred for plants that resent root disturbance or require longer greenhouse growth.
The Importance of Hardening Off
Hardening off is the process of acclimatizing an indoor-grown starter plant to the fluctuating conditions of the outdoor environment before permanent planting. Indoor-grown plants are accustomed to stable temperatures and indirect light, making them highly susceptible to damage from sun, wind, and temperature shifts. Skipping this step can cause transplant shock, leaf scorching, severe wilting, or plant death.
The process typically spans seven to fourteen days and involves gradually increasing the plant’s exposure to outdoor elements. Begin by placing the potted plants in a sheltered location, such as a shaded porch, for two to three hours during the first day. This initial exposure allows the plant’s cuticle—the waxy protective layer on the leaves—to thicken in response to drier air and air movement.
Over the next few days, progressively increase the duration of the outdoor stay by an hour or two, keeping the plants protected from intense sunlight. After about five days, introduce the plants to periods of direct morning sun. This gradual shift prompts the plant to slow vegetative growth and allocate resources toward developing stronger, more resilient tissues.
By the end of the second week, the starter plants should tolerate being outside for a full 24-hour cycle, including moderate wind and slight temperature drops. This slow transition allows the plant to naturally toughen its cell structure and adjust its physiological functions before the final move to the garden bed.
Proper Transplanting Techniques
Once the starter plant is hardened off, transplanting requires careful execution to minimize root disturbance. Prepare the planting hole to be slightly wider than the root ball, but no deeper than the container it currently occupies. Loosen the soil at the bottom of the hole to encourage downward root growth, and incorporating compost can provide immediate nutritional support.
Timing the transplant is beneficial in the late afternoon or on an overcast day, allowing the plant a recovery period without the stress of intense midday sun. To remove the plant, gently hold the base of the stem and invert the pot, tapping the bottom to release the root ball.
If the roots are tightly circling the soil mass (root-bound), gently tease them apart or make four shallow vertical cuts along the sides to encourage outward growth. Place the plant into the hole, ensuring the soil line of the root ball is level with or slightly above the surrounding garden soil, as burying the crown can lead to stem rot.
After positioning the plant, carefully backfill the hole with soil, lightly tamping it down to remove large air pockets. Immediately provide a thorough watering to settle the soil around the roots, eliminating air gaps and initiating the plant’s establishment in its permanent location.