Transplanting Seedlings in the Greenhouse
Today at my Bedford, New York farm, we're expecting sunshine with temperatures in the mid-50s - pretty mild weather for February. We're getting a lot of work done outdoors and indoors.
Inside my main greenhouse, we've already planted lots of seeds for the coming gardening season and they're all growing nicely - most of them are from Johnny's Selected Seeds, a source I've used for many years. Starting from seed is not difficult to do, but it does require careful attention and patience. And, once the seedlings start to develop, it’s important to keep up with maintenance care - thin out seedlings that are weak, prick out those that are growing too big for their seed starting trays, and transplant them into larger pots and flats.
Here are some photos, enjoy.
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- Seed starting trays and pots come in all different sizes and depths. These flats have individual pots which will accommodate seedlings that are now ready to transplant from smaller containers. Experiment with pots to see which ones work best for what plants. And, always choose containers or trays that have proper drainage holes at the bottom. Johnny’s Selected Seeds offers a huge variety of seedling trays and other vessels.
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- Wendy Norling, who usually works at Skylands, my home in Maine, is visiting New York and working at my Bedford farm for a couple weeks. Here she is preparing a series of flats with pots so she can transplant some of the growing flower seedlings.
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- Wendy fills the pots with a good all-purpose potting soil mix. 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.
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- This tool is great for transplanting seedlings – it’s from Johnny’s Selected Seeds. It’s called a widger. It has a convex stainless steel blade that delicately separates the tiny plants.
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- Regardless of how perfect seeds may appear, germination is never guaranteed, so multiple seeds are always planted in each seed starting tray cell. This provides a better chance at least one in each cell will take root. When the seedlings are 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 – removing the weaker sprouts and leaving those that have a better chance of growing strong. Once selective thinning is complete, there should only be one seedling in each cell of the seed starting tray or container. These hollyhock seedlings are big enough to transplant.
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- Wendy carefully loosens the soil around the seedling with the widger and lifts the seedling. The widger also helps to avoid damage to the plant’s leaves or roots.
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- Hollyhocks have long taproots as well as lateral roots that need space, so the deeper the pot, the better.
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- Wendy uses the wider end of the widger to create a hole a couple inches deep in the new pot.
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- These holes can also be made with one’s finger – the mix is very soft.
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- Wendy places the seedling in the hole and gently firms up the surrounding soil. Avoid handling the seedling by its tender stems, which can bruise easily.
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- The growing seedlings will remain in the new larger pots until they are ready to plant in the ground.
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- Each plant also gets a sprinkling of Osmocote fertilizer – available at Martha.com.
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- Osmocote is a slow-release fertilizer. Osmocote particles are known as prills. The beige shell on the prill coats a core of nutrients – nitrogen, phosphorus and potassium.
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- My gardeners spend many cold, winter days planting seeds in trays. Some are placed in a smaller greenhouse adjacent to the head house. These seedlings are in different stages of growth. As they germinate and begin to mature, it’s important to check their development, so they continue to thrive. These seedlings are dianthus, treasured for its grasslike, blue-green foliage and abundant small and often spicily fragrant flowers.
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- These seedlings are foxglove, Digitalis purpurea. Foxglove flowers are clusters of tubular shaped blooms in colors of white, lavender, yellow, pink, red, and purple. These were planted from seed a few weeks ago and already transplanted into larger pots. The purpose of transplanting is to provide enough room – overcrowding can stress the sprouts. These look so much better in the pots.
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- And these are lupines – colorful spiked flowers that grow one to four feet tall. These are also growing in flats in the greenhouse.
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- I also use my Urban Cultivators. I have one commercial unit and two smaller residential units in my head house. Once seeds are planted in trays, they are covered with humidity domes which remain positioned over the seed tray until germination begins. Each tray receives about 18-hours of light a day with the appropriate amount of water and humidity.
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- These seedlings already germinated – the covers have been removed. Inside the Urban Cultivator, they are receiving the best growing conditions. It is fascinating to watch the plants grow.
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- All our hollyhock seedlings are now transplanted and fed in their larger containers.
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- Finally, Wendy gives them a good drink of water and returns the flats to the greenhouse to continue growing. And then it is back inside to transplant more – thanks, Wendy. We’ll have a lot of flowers and vegetables to plant outdoors this season.
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