Seed Starting Demystified (2024)

Seed catalog season, one of my favorite seasons of the year, has begun. Few tasks are more rewarding than growing your own plants from seed. If you haven't done this before, and you find it intimidating, here are some guidelines to simplify the process.

Which seed catalogs to choose?

Choose seed companies in the Northeast. They provide varieties adapted to our area, whereas more distant companies may offer plant materials best suited to other regions of North America. Some of the companies I have used with good results: Burpee, Johnny's Select Seeds, The Cook's Garden, and Annie's Heirloom Seeds.

How to read seed catalogs

The best catalogs include details such as the botanical name of the plant, its color, preference for sun or shade, its water requirements, and the mature height and spread of the plant. Another important piece of information is the cold-hardiness zone for the plant. The catalog may tell you the plant is new or improved which means the variety has changed, hopefully for the better. Icons will indicate the plant's traits: read the key, as the symbols are not the same in all catalogs. You may have been drawn to the plant by its lovely picture, but remember this shows the mature plant at its best; perennials may not look that way the first year. Don't forget to grow some flowers in your vegetable garden to encourage pollinators. Many annual flowers, like marigolds and zinnias, are very easy to grow from seed; they are great for beginners.

How many seeds to order

For a modest-sized garden choose the vegetables and varieties your family enjoys most. One packet of seeds of each variety should be plenty. As a general rule, one packet will be enough for a 10 to 30 foot row.

When to start your seedlings

Plan to start your seeds indoors so they are at the correct stage of development to move outside after the last frost. I often wait another week before planting, if the weatherman predicts frost at that time. Follow the instructions on the seed packet and use the calendar to figure out the sowing dates. For example, the instructions on a tomato seed packet may be, “Start seeds indoors 4-8 weeks prior to the last frost of spring." Always read the directions on the seed packet, as larger seeds, such as beans and corn, do best if you sow them directly into the garden. Write the sowing date on each seed packet and group together with other packets having the same sowing time.

Containers

You will need containers with holes for drainage and trays to catch excess water. Styrofoam cups, plastic tubs, and old plastic cell packs are suitable. I prefer old seed flats. You can purchase a seed starting kit that includes a tray of cells and a humidity dome, but it's not necessary to spend the money. Most important, your containers must be properly sterilized before using them. Wash them in soapy water and then rinse with a solution of one part chlorine bleach and 10 parts water. Dry thoroughly before adding the growing mix.

Growing mix

Purchase a commercially prepared mix especially for seed starting. The medium should be sterile, loose, well-drained, and of fine texture. Also, buy vermiculite to cover the seeds as this encourages seed germination.

Step-by-step procedure

  • Moisten the seed starting mix and fill the container to within ¾ inch from the top. Remember to make sure the container has adequate drainage.
  • Use a clean small board to level and firm the mix. Do not press too hard.
  • Make shallow rows about 1-2 inches apart with a narrow board.
  • Sow seeds uniformly and thinly in the rows. Label the rows immediately, especially when you plant different seeds in one flat. If you are sowing only one type of seed you may scatter them over the surface.
  • Cover the seeds with vermiculite to a depth of about two times their diameter, leaving very fine seeds uncovered. Moisten the surface with a fine mist, or place the container in a pan of warm water.
  • Cover the container with a plastic film or a plastic bag. No additional watering will be needed until after germination.
  • Place the tray in a warm place, not in direct sunlight, with a temperature of 65–75° F. You can use a heated seed-starting mat.
  • Once seedlings emerge, remove the plastic film and place the container in a bright south-facing window, or under a fixture equipped with two cool white fluorescent tubes. Leave the seedlings under the lights for 14-16 hours each day. Do not overwater: allow drying between watering, being careful the seedlings don't wilt.
  • If you need to thin your seedlings, nip some off at the soil line with scissors. If necessary, transplant overcrowded seedlings to individual pots after they have at least one set of true leaves. Grasp the seedlings by the leaf to avoid damage to the stem.

Hardening off and planting out

Gradually introduce your seedlings to the garden after threat of frost. Place them in dappled shade for about five days before moving them into a sunny location, gradually increasing the length of exposure, for another five days. When your plants are large enough for easy handling and hardening-off is complete, the time has come to plant them into the garden. To reduce the shock of transplanting, select a cloudy day for the task. Dig a hole twice as wide as the plant. Carefully remove the plant, retaining as much soil as possible, and set it in the hole at the same level it was growing in the flat. Place soil loosely around the roots and fertilize with a weak solution of fish emulsion.

With seed catalogs in hand, you can begin the most rewarding and enjoyable of garden projects—planning your summer garden!

Seed Starting Demystified (2024)

FAQs

What is the third mistake people make when starting seeds? ›

3) Using the Wrong Soil or Potting Medium to Sow Seeds

Another common seed starting mistake that new gardeners make is using just any old soil to start their seeds in. Old soil from the garden or yard may contain and introduce diseases or pests to your new seedlings.

Why do seeds germinate better in the dark? ›

The presence of light tends to inhibit their growth. The light decomposes carbonic acid gas and expels oxygen which leads the seed to harden. These gases are key factors that promote germination. In dark environments, the gases remain undisturbed and germination is favoured.

Is seed starting worth it? ›

However, starting your own plants from seed can be a more affordable and more rewarding way to get your garden started for the season. This requires that plants with longer maturity periods be started from seed indoors 6-8 weeks before it is warm enough to start planting things outdoors.

How many seeds should you put in a seed starter? ›

Add one seed to each pot or cell. Use the crease of the seed packet or place seeds in a creased piece of paper to help direct the seeds where you want them to go. Sometimes not every seed will germinate. To increase your chances of success, add 2-3 seeds to each pot and thin out the extras once everything has sprouted.

What are some common mistakes that people make when trying to germinate seeds? ›

8 Common Seed Starting Mistakes to Avoid
  • Using Inferior Growing Medium. Whatever you do, don't go cheap or skimp on your seed starting medium. ...
  • Starting seeds in cold, wet soil. ...
  • Planting Seeds Too Deep. ...
  • Not Labeling Growing Containers or Trays. ...
  • Not Enough Light. ...
  • Too Much Water. ...
  • Not Giving Seedlings Enough Attention.
Apr 5, 2019

What are the three 3 generations that make up the seed? ›

The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte that will provide nutrients, and the embryo itself. Figure 26.2.

Which two conditions do most seeds need in order to germinate? ›

All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate. When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat.

What makes a seed germinate faster? ›

Pre-Soaking.

This method could be the fastest way to germinate seeds. Place seeds in a shallow container in warm water and leave them for 16 to 24 hours (smaller for 16, bigger for 24). Remember not to expose seeds to temperatures higher than 80°F (26.6°C) and not to pre-soak seeds for more than 24 hours.

How many hours of light do seeds need to germinate? ›

Most seeds will not germinate without sunlight and will perform best with 12 to 16 hours each day. Indoors, place seed containers in a sunny, south-facing window and give the container a quarter turn each day to prevent the seedlings from overreaching toward the light and developing weak, elongated stems.

Is potting soil OK for seed starting? ›

Although potting soils may be used to start seeds, they tend to have a more coarse texture and may contain field soil, compost or composted manure along with vermiculite, peat moss or perlite. Some seed-starting or potting mixes may contain fertilizer as an additive.

Should I use worm castings in seed starting mix? ›

DIY: If you want to build your own seedling mix, you will want to add worm castings to an existing seed starting mix or potting mix. You want to aim for about 10-33% of the mixture to be worm castings and the remainder of the mixture being your potting mix (bonus points if you add sifted compost).

Is it bad to start seeds too early? ›

Whatever your temptation, know that starting seeds too soon does more damage than good. Some seeds do well in the colder, darker late winter days–including lettuce, onions, hardy brassicas, and seeds that are slow to germinate, like hot peppers and celery.

Does 1 seed equal 1 plant? ›

In general, two to three seeds should be planted per hole. Seeds do not have 100% germination rates, so not every seed planted will sprout. Overseeding holes, cells, or pots will help ensure that the number of plants you desire will grow (or more.

How long can seedlings stay in egg cartons? ›

But you also can't leave your seedlings in their egg cartons for too long, waiting for the weather to heat up. Seedlings should be moved to the garden once the roots reach the bottom of the tray, but before they start to grow into a circle.

Should I water starter seeds every day? ›

Generally, vegetable seedlings require watering every 1-2 days. It's essential to check the soil moisture; it should be moist but not waterlogged. In hotter or drier climates, or under intense grow lights, you may need to water more frequently.

What are the third steps of seed germination? ›

What are the 3 stages of germination? The three stages of seed germination are 1) imbibition, 2) respiration, and 3) cell division. The first stage corresponds to the absorption of water, the second to the resumption of metabolic activity, and the third is important in the formation of the seedling and the young plant.

What are the 3 stages in a seed plants life cycle? ›

The haploid phase, the gametophyte phase, and the diploid phase, commonly referred to as the sporophyte phase, are the three phases that make up the Life of Plant Cycle. These stages alternate, which is referred known as the alternation of generations.

How do some seeds fail to germinate? ›

Inadequate Moisture. Too Much Moisture. Too Little Oxygen From Compacted Soil. Estimated Germination Window Hasn't Ended.

Is there a wrong way to plant seeds? ›

The rule of thumb is to plant seeds at a depth equal to two or three times their width. It is better to plant seeds too shallow than too deep. Some seeds, such as certain Lettuces or Snapdragon, need light to germinate and should not be covered at all.

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