Master Gardeners: A step-by-step guide to outdoor seed starting

An inexpensive and easy way to start seeds now outdoors is indeed possible by repurposing plastic milk jugs, notes University of Illinois Extension Master Gardener, Ellen Meyer. “I start with clear, gallon milk jugs that I prepare to hold the soil mix and seeds,” notes Meyer. “But plastic clam shell and lettuce containers work, too. The rule of thumb is that you must be able to see your thumb through the plastic for the container to work.”

Meyer says that containers need to hold 3” of potting mix and have head room for a 4” plant to grow. To prepare milk jugs, begin by making a horizontal cut 4” up from the bottom of the jug. Start the cut 1-1/2” to the right of the handle’s base and continue around, stopping 1-1/2” before the other side of the handle.  Create a total of 4 drainage holes in the bottom, as round as a pencil, one in each quadrant. Finally, use a hole puncher to make a hole in the top and bottom sections where a twist tie will hold them together. For other containers, space drainage holes about 4” apart. Ventilation and watering holes must be made in tops without them and should be about the same size as drainage holes. Milk jugs rely on the pouring hole for ventilation and watering, so leave the caps off.

Standard potting mix works well for seed starting. Meyer has found, “Moisture control, fertilizer added or seed starting mixes aren’t as successful for this and typically cost more.  Absolutely don’t use soil from your garden as it isn’t sterile.”

Plant the seeds according to package directions and water them until you see droplets coming out of the bottom. For milk jugs Meyer then uses a twist tie through the two holes created in front to hold the sections together, lapping the top slightly over the bottom.

Place containers outdoors in full sun until warmer April temperatures arrive, when they will need to be moved to a part shade location. Watch for droplets on the inside of the container and if there are none, it’s time to water. Add fertilizer at one quarter strength to the water once the plants have four leaves on them. Plants can go directly into the ground or planters by mid-May.

Ellen Meyer is a member of the Master Gardener Speakers Bureau and is available to give presentations on Winter Sowing to area organizations. Visit the website below for details. For online help, type Winter Sowing in your search engine and find articles on the topic.

Email your home garden and lawn questions to or phone the Master Gardener Helpline at 630/955-1123. Visit our website at

Julie Moore has been a Master Gardener volunteer with the University of Illinois Extension in DuPage County for 10 years and has a degree in Ornamental Horticulture from the University of Illinois.


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