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Springtime is near. Get your seedlings ready now.

Over the Garden Fence: Where, When and How to Transplant New Seedlings

By Bob Labozetta, UC Master Gardener, Mariposa

MARIPOSA — So you’ve started your seeds in pots or trays and they have sprouted. Now what? When it’s too early to transplant seedlings out into the garden, but they’re too big to remain in their first containers (or your seedlings are crowding each other), you need to transplant them into bigger pots such as 3-4″ peat or upcycled containers such as red solo cups.

Your seedlings are ready for transplanting and feeding when they have 2-3 sets of true leaves. The first leaves (known as cotyledons) emerge when a plant germinates to provide nutrients to the seedling until its true leaves unfold. A second set of “true” leaves will appear above the cotyledons. When a seedling is ready to move to a bigger pot, it requires some added nutrients. Transplant them into a soil or compost mix that contains more nutrients.

Let your seedlings acclimate to their new home for a few days before adding anything. If desired, you can fertilize with a greatly diluted fertilizer (at ¼ strength). Fish emulsion or phosphorus works well.

Moisten the potting mix, then press it gently into the new container. Make a little space with your finger or small implement, gently remove the seedlings from their original container, place them carefully into the holes you’ve created, and lightly tamp the soil around the base.

Most vegetables should be transplanted at the same depth they were growing, with a few exceptions. Tomatoes, for example, can be buried deeply up to their first leaves.

Keeping the soil moist, place seedlings in a warm, bright location such as a greenhouse or under grow lights until it’s time to BEGIN the process of moving them to the garden. Transition your tender plants from inside to outside by “hardening off,” or slowly exposing them to the elements of changing temperatures, varying levels of sunlight, and wind.

When the weather is consistently warm, place your transplants outside for an hour or two. Protect them from the wind and sun. Place them outside for just an hour or two and leave your seedlings outside each day for an hour more than the previous day, gradually giving them more and more direct sunlight time and less shelter until they’ve begun to spend the whole night outside. Bring the seedlings inside if temperatures dip during hardening off and use row covers for extra security and warmth if there’s a hard rain or cold-weather day. Water as needed.

You’re well on your way to a successful garden!
UC Master Gardeners of Mariposa County are located at 5009 Fairgrounds Rd., Mariposa. For more gardening and event information, visit our website (http://cemariposa.ucanr.edu/Master_Gardener/) and Facebook page (UC Master Gardeners of Mariposa County.

UC Master Gardeners staff a Helpline serving Mariposa County, including Greeley Hill, Coulterville, and Lake Don Pedro at 209-966-7078 or mgmariposa@ucdavis.edu. Listen to us on the radio at KRYZ 98.5 FM on Wednesdays at 2 p.m. and Saturdays at 5 p.m.

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