1 The seedlings for my vegetables and flowers are all growing very nicely in the greenhouse. To ensure these young seedlings continue to thrive, it's a good time for some maintenance care.
2 Regardless of how perfect seeds may appear, germination is never guaranteed. Because of this, multiple seeds are always planted - usually two seeds in each cell of a seed starting tray. This provides a better chance at least one in each cell will take root.
3 When the seedlings are at least a couple inches tall, and have reached their "true leaf" stage, which is when each seedling has sprouted a second set of leaves, it's time for a process called selective thinning.
4 Selective thinning prevents overcrowding, so seedlings don't have any competition for soil nutrients or room to grow. This process should be done several hours after watering to minimize stress on the remaining sprouts.
5 When thinning, carefully inspect the seedlings in each seed starting tray cell and determine the stronger of the two. Look for fleshy leaves, upright stems, and center positioning in the space.
6 Using a small pair of scissors, clip the smaller, weaker, more spindly looking seedling. This is also the seedling that is less likely to survive.
7 Cut the undesired seedling as close to the soil line as possible, so nutrients go directly to the remaining plant. Another option is to pull the seedling out completely, but this could cause root disturbance to the remaining sprout.
8 Once selective thinning is complete, there should only be one seedling in each cell of the seed starting tray. Not only does this allow for better growth, but it also creates better air circulation for all the neighboring seedlings as well.
9 All the seedlings in the greenhouse were inspected, and thinned where needed. This offers the best environment for the stronger, more healthy, growing sprouts.
10 Each seedling now has more room to grow into a stronger plant before it is transplanted into a larger pot or into the ground.
11 As seedlings outgrow seed starting cell trays, they need to be pricked out and transferred to individual pots, or larger trays. This process should not be done until the seedling has hit its "true leaf" stage. The first set of leaves are the cotyledons, or seed leaves. The second set are the true leaves, which better resemble the leaves of the mature plant.
12 A good quality organic mix designed for seedlings will be fast draining, and light. It will usually contain sphagnum moss and perlite or vermiculite. These mixes are formulated to encourage strong, healthy growth in new plants.
13 Fill the new, larger pot with good quality seed mix, and using a dibber or a finger, poke a hole in the center of the container or larger cell.
14 Place the seedling in the hole and gently firm up the surrounding soil. Again, avoid handling the seedling by its tender stems, which bruise easily - always use their seed leaves.
15 The growing seedling will remain in the new pot until it is ready to plant into the ground.
16 Smaller seedlings started in undivided trays should be pricked and transplanted into seed starting packets with individual cells when they are ready.
17 Fill the entire tray with moist seed mix, tap the soil down to eliminate any air pockets, and to fill all the corners. Again, poke a hole into each cell.
18 This task of pricking and transplanting small seedlings is good for an assembly line process. It is also best to prepare the planting holes before lifting the seedings from the sowing tray, so seedling roots spend the least amount of time exposed to the air.
19 When it is time to move the seedling, carefully loosen the soil around the young seedling with a wooden marker. Again, try to handle seedlings by their cotyledon leaves to avoid damage to the plant's stem, true leaves, or roots.
20 Notice the strong root system and the green, fleshy leaves. Pricking out and transplanting is best in the late afternoon or evening, so seedlings lose the least amount of water and can recover from the move overnight, when temperatures are cooler.
21 The purpose of transplanting the seedlings is to give them enough room - overcrowding can stress the sprouts.
22 Depending on how many seedlings need transplanting there are always many different kinds of pots and trays available. It's a good idea to save those plastic pots that come with annuals purchased at the garden center - they always come in handy.
23 Experiment with pots made from different materials to see which work best for what plants. And, always choose containers that have proper drainage holes at the bottom.
24 After all of my seedlings were transferred, they were given a good drink and returned to the greenhouse to continue growing until they are moved into the outdoor beds in a few weeks.