The Keys to Growing Healthy Transplants

  

  

Caring for seedlings after germination includes providing the right conditions for optimal development. The three factors that will have the most influence on how well your seedlings grow and develop are light, water, and fertilizer.  

  

Seedlings need a consistent source of the right light and most of the time the light coming through a bright, sunny window isn’t going to be enough for your seedlings. They will tend to stretch and get thin and spindly looking for light.   

  

You have several choices when it comes to selecting a grow light including high-output T5s and LEDs. T5 fixtures tend to cost less initially, and the bulbs are replaceable. Select a T5 in the 6400K spectrum, for best seedling growth.  

  

LED options include 24” and 48” fixtures as well as bulbs. LED lights are brighter and more energy efficient than T5’s. 

  

Plan to run your grow lights fourteen to sixteen hours per day. It’s also important that your light setup is adjustable, so that you can raise the lights as your plants grow.

When your seedlings are small, place your lights five to six inches above the tops of the plants. As the seedlings grow and develop, adjust the lights up accordingly.

Fluorescent lights should be suspended 10 to 12 inches from your seedlings, LEDs 8 to 10 inches and incandescent bulbs 12 to 18 inches.   

  

In addition to a dependable light source, maintaining a consistent watering schedule is also important. Check your seedlings every day and keep the soil moist, not soggy. Don't use water that is too cold (or too hot). Fill up your watering can and let it set out overnight. That way the water will be at room temperature when you water your seedlings.   

  

To develop strong stems and root structures, your seedlings need to be fed. Begin fertilizing once your tomato and vegetable plants have 3-4 sets of true leaves. The first set of leaves to emerge are the cotyledons, sometimes referred to as ‘seed leaves”. They are not “true leaves”. The next set of leaves and all subsequent leaves are true leaves.   

  

Use a mild organic fertilizer with a balanced formula such as 2-2-2 or liquid Kelp. Liquid fertilizers are preferable at this stage because it’s less likely you’ll damage the seedling’s roots than if you used a granular starter fertilizer. Plan to fertilize your seedlings every 10 to 14 days.  Let your water sit out overnight to reach room temperature, before applying it.   

  

If you used a humidity dome for starting your seeds, now’s the time to take it off. Leaving the humidity dome in place can encourage fungus and mold to develop. Same is true of heat mats. Leaving heat mats in place can lead to bolting and weak stems. 

  

Seedlings, especially tomatoes, need air movement to develop strong stems. Place a small fan nearby to create air flow. The air movement will also help prevent fungal issues. In lieu of a fan, brush your seedlings with your hand a couple of times a day.  

  

One other important task is to give your seedlings plenty of room to grow by thinning out weak plants. This is especially important for tomato and pepper plant seedlings. Cut off the weakest seedling with a pair of sharp trimming scissors. Don’t attempt to pull it out of the pot. This will damage the root system of the seedling you’re trying to keep.  

  

Maintaining the right growing environment and supplying your seedlings with water and nutrients will help ensure the best quality plants for transplanting into the garden.