Starting Seeds Indoors: 8 Critical Mistakes Most New Gardeners Make

Give your garden a good start by avoiding these rookie blunders.

Sow Seeds Indoors or Out

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Sow seeds indoors or out

Starting seeds indoors is a great way to get a jump on the growing season. It allows us to efficiently care for lots of baby plants in a small, controlled space away from garden pests. And, it extends the growing season. In many areas, garden favorites like tomatoes and peppers, wouldn’t have enough time to grow and produce edible fruit if we sowed the seeds directly in the garden. Although there are a few plant types that grow best when sown directly, such as carrots and beets, many others benefit from an early start indoors.

Starting seeds is not difficult, after all it happens in nature with no help from people. But there are some things you need to know if you want to grow strong, healthy plants. Too many new gardeners learn these lessons the hard way. We’ve compiled the following list of common missteps, so you don’t have to repeat them.

Related: Starting Tomatoes from Seed

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Poor Timing

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Poor Timing

It’s frustrating when seedlings are either overgrown or underdeveloped when planting time arrives. Each seed type germinates at its own pace. Some sprout almost as soon as they touch the soil. Others take a few weeks to emerge. Then they need to reach the right stage of maturity, with at least four true leaves, before transplanting. Plan on starting garden seeds indoors one to two months ahead of transplanting time. The best way to know when it’s time to plant is by checking the back of the seed packet. The packet usually includes instructions for starting seeds indoors, with timing based on the average last frost date in your area.

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The Wrong Soil

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The Wrong Soil

Garden soil, potting soil, and seed starting soil are labeled as such because of what they can and cannot do well. The first two are designed to support mature plant growth, but are too heavy and coarse for seed starting. Seed starters like Black Gold Seedling Mix are designed to retain the right amount of moisture for germination and plant early growth. This is a lighter mix, typically made with fine textured peat moss, vermiculite, and perlite. The fine texture allows young seedlings to emerge and spread their roots with minimal resistance.

Related: How To: Test Soil pH

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Lighting on a Slant

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Lighting on a Slant

It's possible to germinate seeds on a sunny windowsill, but the results are usually not great. The intensity of the light may be good, but the sun’s angle promotes tall, spindly (leggy) plants that grow on a slant toward the sunshine. However, there’s no need for an expensive grow light system, since the plants will be moving outside in just a few weeks. An affordable solution is to mount a portable LED or fluorescent light fixture directly over the plant tray, with the bulbs two to six inches above the leaf surface.

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Flood (or Drought)

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Flood (or Drought)

Too much and too little water both kill plants, so it’s important to water correctly. Pre-moisten the seed starting soil so that it feels like a wrung-out sponge before putting the soil into the seed tray. Then sow the seeds and cover the tray snugly with a plastic cover. There is no need for additional water until the seeds sprout, which is when the cover is removed for ventilation. Note the weight of the tray after sowing the seeds, as this will be a clue for future waterings.

When the seedling tray feels light, it’s time to water. Do not wait until the soil dries out to the point of changing color or shrinking away from the sides of the tray. Use a quart size watering can or spray mist bottle to water from above. Another watering method involves adding a ¼-inch of water to the plastic or metal tray beneath the seedlings and allow the moisture to wick up into the plant root zone. Drain away any excess water.

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Cool Bottom

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Cool Bottom

Most seeds sprout quickly within a temperature range of 65 to 75 degrees Fahrenheit. Some like it a bit warmer. Both ambient air temperature and soil temperature affect seed germination. If a home is on the cool side, use a seedling heat mat to raise the soil temperature 10 to 20 degrees above the ambient air temperature. Or just put the tray directly on top of a refrigerator where it will benefit from the motor’s warmth.

It’s also helpful to enlist the help of a fan to keep the air moving around seedlings as you start to water them frequently. This will help to avoid damping off, a disease caused by fungus that thrives in cool, wet soil. Be sure that the fan is not pointed directly at the seedlings, as it can be too strong. The goal is to simply create air circulation in the surrounding area.

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Not Using the Seed Label Information

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Not Using the Seed Label Information

The seed packet almost always contains a wealth of information about the proper time to plant, plant spacing, planting depth, and more. Some suppliers use a generic packet for all of their seeds, but include more detailed directions on their website. Because different varieties of the same vegetable or flower, like ‘Better Bush’ and ‘Sweet 100’ tomatoes, may perform best with slightly different care, use this information from the seed supplier as the first source of info.

Related: 10 Easy-to-Grow Vegetables for Beginning Gardeners

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Growing Seedlings Too Densely

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Growing Seedlings Too Densely

There is no need to force seedlings to compete for resources. One benefit of using seed trays is the ability to use seeds efficiently, so more plants grow from each seed pack. Each seed will become a plant, and the cells in the tray are the right size for just one. If the seeds are fresh, there is no need to sow more than two per cell—one to grow, and another seed in case the first one doesn’t grow. In most cases, only one seed needs to be planted per cell, but many gardeners plant a few extra cells as an insurance policy.

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Moving From the Kitchen to the Garden

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Moving From the Kitchen to the Garden

Hardening off is the gradual transition from protected indoor growing conditions to the exposed garden plot. If seedlings are moved from indoor production directly to the garden, they may die. Instead, start by placing them in a shaded area outdoors for a few hours at a time. Gradually increase both the time spent outdoors and the amount of direct sunlight they receive each day over a one to two week period before finally planting them in the garden. Be sure to follow the planting guidelines from the seed packet concerning weather and proper plant spacing.

Related: 11 Indoor Gardening Projects Absolutely Anyone Can Do

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Getting Started

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Getting Started

Avoid these mistakes, so your seeds grow into flourishing plants.

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