The Right Way to Prick Out Seedlings

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Tomato seedlings

About half of the seedlings I start indoors grow exactly as they should, with one sturdy plant near the middle of each seedling container, so that the root ball forms a plug plant type mass. The others come up crowded, and need to be 'pricked out' – gardening lingo for separating the little seedlings and transplanting them to individual containers.  Gardeners who buy seedlings also do a fair amount of pricking out, because it’s not unusual to find several lettuce, basil or even tomato seedlings growing in the same pot. Transplanting the young seedlings to individual containers can double or triple your supply of plants.

Most vegetable and herb seedlings are easy to prick out as long as you do it while they are young and have fewer than 5 leaves.  Getting organised ahead of time is important, too, because once your hands are covered with soil, you don’t want to stop to make labels or find more containers. Using the following step-by-step procedure, I seldom lose a seedling.

  • Prepare the patients. Pricking out is a form of surgery, so the seedlings should be in top condition. Water them several hours before you begin, and protect them from any type of stress. 
  • Prepare the compost soil.  Place as much compost as you need in a pail, and lightly moisten it with warm water. If the soil is cold from sitting outside, bring it indoors and give it time to come to room temperature.
  • Prepare containers. Wash out plastic pots that have previously been used. Many sources recommend disinfecting containers at this point, but I think washing them with warm, soapy water is sufficient. When using paper cups or recycled containers like yogurt cups, poke at least 3 drainage holes in the bottom of each one.
  • Label containers. Part of the beauty of paper cups is that you can write on them using a permanent marker. On the other hand, plastic markers can move to the garden with the plant, which makes it easy to tell one variety from another. I make markers from plastic food containers taken out of the recycling bin, cut into narrow 3-inch strips.
  • Pricking out seedlings into paper cups
  • Partially fill containers. Sprinkle enough moistened potting soil into the containers to fill them about one-half full.  
  • Remove the seedlings. Push up on the bottom of the seedling container, and be ready to catch the root ball with your other hand. This is easiest if you can hold the container sideways or upside-down. Place the seedlings on a flat surface that is shaded from direct sun. Poke at the roots until the root ball shatters.
  • Replant the seedlings.  Grasp a leaf from the most accessible seedling, and gently lift it until it comes free. Use a stick or pencil to help guide the lowest roots into the new container, but don’t worry if they spiral around a bit. Still holding the seedling with one hand, sprinkle moist potting soil around the roots until the proper planting depth is achieved. Use a stick, pencil, or your fingers to firm the soil over the buried roots. Then do the same with the other seedlings.
  • Water and wait.  Stop every ten minutes or so, and water the seedlings you have pricked out. Then return them to exactly the same environment in which they were growing during the previous week. To give new roots time to grow, wait at least three days before moving the pricked-out seedlings to brighter light. 

I often wait until I see signs of new growth to move seedlings outdoors to grow in brighter light, or to begin hardening off seedlings in preparation for setting them out in the garden. Most pricked-out seedlings recover from transplanting trauma in a few days, and show new growth within a week. Those that won’t go into the garden for several weeks will need to be shifted to larger pots, but "potting up" older seedlings with strong root systems is a piece of cake compared to the slow, delicate work of pricking out.

By Barbara Pleasant

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Comments

 
"when can you tell if leeks are read y to prick out - mine look very leggy"
di green on Saturday 3 April 2010
"I grow in excess of 6,000 annuals (french marigolds, asters, alyssum geraniums etc etc) every year. Today, there are many different potting composts on the market. Years ago, we had a choice from J. Arthur Bowers, John Innes No.1, 2 or 3 and a few others. Today, the local DIY stores and garden centres have their own brands. This year, I bought a brand name of which I had never heard and, when using it, came across small segments of GLASS and stones resulting in me having to sieve every sack full. Even then, I'm not a happy bunny. Has anyone else found a similar complaint? On a different subject, when sowing fine seed, for the past 50+ years, I've been mixing the seed with silver sand and then placing this on top of either a pot or seed tray full of compost. Is this still the accepted way or is vermiculite the 'modern' method? "
Doug Beard on Saturday 3 April 2010
"Yes, leeks as well as other onion seedlings do get quite leggy. I use a small pair of scissors to clip the tops back to less than 6 inches (15 cm) about once a week. They can go even shorter, but it not relieved of the excess top weight they will fall right over. In the US, there are now organic vermiculite-based seed starting mixes widely available that are great for starting seeds. When I prick out into potting soil, I use a regionally-produced organic product. Superior potting soils are worth seeking out, and when you find a winner, stick with it! "
Barbara Pleasant on Sunday 4 April 2010
"I have been growing annuals and perrenials for some time now and have experimented with different brands of soil. One brand in particular (levingtons) I was seriously dissappointed with. It contained glass, nails, half batteries, large bits of plastic etc. In one bag alone I found 2 half batteries (not one that had been halved). I know some manufacturers have different ways of regulating PH etc but I can't see a plant surviving if its roots got near this. "
Doug on Thursday 15 April 2010
"I agree entirely. For many years, I was a Levingtons devotee but I experienced similar contents in 2009 so this year I've bought two other brands ..... one of which isn't any better!"
Doug Beard on Thursday 15 April 2010
"That's terrible that you found half batteries in the potting compost - I can't believe they didn't use something simple like metal detection to eliminate that. Personally after a lot of experimentation I have found a potting compost I absolutely love, available in the UK. It's called Fertile Fibre and is made from organic coir which gives it a very soft even texture that is perfect for seedlings. It does cost more but I am prepared to pay that for good quality and organic, especially because I lost a whole lot of good seedlings one year due to poor compost. I then use a stronger multi-purpose compost for potting on into pots bigger than 3"."
Jeremy Dore on Friday 16 April 2010
"Jeremy, I'd be interested to know where you bought the Fertile Fibre? Good quality organic potting compost with different elements like coir are difficult to find. The americans seem to have covered this very well with loads of different brands. For regular compost I find Westland with added John Innes pretty reliable. It sometimes has a high bark content but for the price it does the job. I haven't found any nasty surprises in it yet! "
Doug on Friday 16 April 2010
"Doug, It's stocked by http://www.organiccatalogue.com/catalog/ and http://www.tamarorganics.co.uk/ (cheaper) or you can buy directly from them at http://www.fertilefibre.com/shop/. In some places you can get it locally (e.g. Manchester) which is cheaper. Like you I use Westland compost for potting on."
Jeremy Dore on Friday 16 April 2010
"For years, I've had success "pricking" out tiny seedlings and transferring them to other cells where seeds didn't germinate. I like not wasting these infant seedlings and the empty cells. My favorite "tool" has been little plastic picnic forks. With them it's easier to separate entwined seedlings without damaging them."
Clarice McKenney on Tuesday 27 April 2010
"Great tip, Clarice. In fact, many commercial propagators use a plastic fork with two of the tines broken off as a pricking tool."
Barbara Pleasant on Tuesday 27 April 2010
"I have used levington compost for years and have found it the best peat based compost i have tried other conmpost such as BQ and other cheap compost and find they are to full of other materials usually wood fibre. i would put the cause of seed failure to other causes; such as bad seeds and damp greenhouses"
Ian Robertson on Friday 1 April 2011
"Nice tips, thanks a lot!"
Shara on Friday 28 December 2012
"Barbara help! My tomato seedings look anemic after my hardening off process. They are light green in in color and look like they had too much breeze an or sun. They are indoors today. Any suggestions? "
Claudia on Tuesday 14 April 2015
"The first comfort measure to try is to feed the plants with a mix-with-water fertilizer. Get some on the leaves, too, because if the plants are very needy of nutrients, they will take them up through the leaves. Move them to filtered sun outdoors when they perk up. "
Barbara Pleasant on Wednesday 15 April 2015

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