How Does Your Garden Grow?

Common problems and how to harden off seedlings

By Katherine Clarkson
Posted 4/20/21

Last month‘s column explained some benefits of establishing a garden from seed. This month I will describe how to identify and resolve common seed-starting problems. In addition, I will explain …

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How Does Your Garden Grow?

Common problems and how to harden off seedlings

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Last month‘s column explained some benefits of establishing a garden from seed. This month I will describe how to identify and resolve common seed-starting problems. In addition, I will explain how to prepare your seedlings for transplanting.

There are several reasons your seeds may not sprout. Although I often assume a thief came at night and stole my seeds, that is not the problem. Often the issue is some seeds simply have a low germination rate. If this is the situation, the package will say to sow heavily. Another reason is the seeds are old. On average the first year you purchase your seeds they have an 80% or higher germination rate. Each additional year decreases that rate by 10%. If you are uncertain how old your seeds are, place 10 in between a damp paper towel and then in a plastic bag. After a week or two, the amount that sprouts will be the percent of seeds that are good.

After your seeds have sprouted, they will often express deficiencies and the most common dilemma is they become leggy. This means they look pale, thin and tall, and cannot withstand windy conditions. Leggy plants are caused by insufficient lighting or overcrowding. When seedlings are overcrowded, they shade each other out.

To amend this, thin your seedlings by removing smaller ones and leave the larger. To help leggy seedlings, you can add a grow light. If you are using a fluorescent bulb place the light about 10-12 inches away, and for a LED grow light 24-36 inches away. If your light yields a lot of heat, you will want it up higher so your plants do not burn. Keep in mind that each grow light is different so the exact placement will vary.

Another issue is fungus gnats, which are small grayish black flies that are about 1/8 inch long with lengthy legs and transparent wings. They result from over-watering. While the adult flies do not cause damage, their larvae feed on the roots, which inhibits the seedlings from receiving proper nourishment. To eradicate this, let the seedlings slightly dry out between watering or hang yellow sticky traps next to the soil. If you encounter other complications, reach out to a Park County master gardener at https://parkcountymg.weebly.com/contact.html.

Once the weather permits, it is essential to harden off your seedlings before you transplant them outside. Harden off means you accustom plants to the intense sunlight, cooler nights and less frequent watering. There are several techniques to harden off your crops. This column will outline the basic steps. 

The hardening process begins about 10-14 days before you transplant your seedling. First, gradually reduce watering, but do not reduce watering so much that it provokes injury to the plant. Next, watch the weather forecast and learn the relative hardness of your crops.

The following are common vegetables and their hardness temperatures: Squash, eggplant, tomatoes, peppers and zucchini are best hardened-off at 60-65 degrees; cold crops such as swiss chard, kale, and Brussels sprouts are best hardened off at 55-60.

When the day’s forecast is at the preceding temperature, take your seedlings outside in a shady wind protected area for two to three hours. I put my plants in a storage tote to offer protection from our Wyoming wind. And be creative with ways to protect your seedlings. For example, use a 2-gallon jug, cut the bottom off and place it over your seedling.

After the plants have been outside, bring them back inside the house or a heated garage. After three to four days, introduce your plants to the direct sunlight for one-two hours. Continue this process for seven to 14 days, each day increasing the amount of exposure to the outdoor elements. Also, consider growing some extra plants just in case you need them. If you do not use them, take this opportunity to share a plant and spread a smile.

If you understand your climate and learn from the trial and error that gardening presents, you will be on track to having a successful season. Also, listen to your plants, let them tell you what they need, and your seedlings will flourish. Thank you for reading and if you have questions or comments, please reach out to me at katherineclarkson2@gmail.com.

(Katherine Clarkson is the president of the Park County Master Gardeners. She lives in Wapiti.)

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