Starting Seeds Inside

As the winter recedes, our thoughts turn towards seeds! Many folks shopping at the co-op in the last few weeks have been asking us how to start seeds inside. Here are some great tips and helpful hints.


You will need a south or east facing window for your seedlings to get the light they'll need. Even if you have a sunny window, many gardeners prefer to grow seedlings under artificial lighting to know that their aspiring plants are getting an even distribution of lighting for a specified length of time.

My experience with growing seedlings has used sunlight from a south facing window, so this seedling advice is based on that. (For a sense of what lighting costs, there is a two-foot long fluorescent grow light fixture for sale at for under $30. It is recommended that the light is adjustable by height and suspended one to two inches above your seedling pots to begin. As seedlings grow, the light needs to be moved further away accordingly.)


Any container that is two to three inches tall is suitable. Some people save yogurt cups or last year's small plant containers. Other people prefer peat pots or seedling tray systems available at hardware stores or garden centers. I've always used a variety of saved containers that sit in a shallow plastic bin. The important factor in whatever you use is that there are holes in the bottom so that water can drain out. Poke three to four holes as needed in collected containers. You will need to cover your planted seeds loosely with saran wrap or other transparent plastic sheeting until seedlings are up. I've used a sheet of plexiglass with good results, but it is good to have saran wrap or plastic sheeting handy since not all seeds germinate at the same rate.


According to the UMN extension, a good soil mixture is two parts loam, one part sand, and one part organic matter. Luckily, garden stores sell pre-mixed bags of soil that are specifically for starting seeds indoors.

A Seedling Plan

It's so fun to choose what you want to grow and it's also easy to get carried away! Available gardening space may dictate how much you can grow, so it's important to plan accordingly for the space you have.

To get organized around what to plant when, organize your seed packs according to when they should be planted.

Most of the food plants I've started indoors are “warm weather crops” such as tomatoes, eggplant, and peppers. These need a longer growing season so it's nice to get a head start especially when craving spring. I've started some “cool season crops” such as lettuce, spinach, peas, and kale indoors and transplanted them into my garden, but these can also be direct seeded into the garden – as I do with carrots and radishes. Some examples of other cool season crops that can be started indoors are cauliflower, cabbage, onions, and broccoli.

Don't forget flowers and herbs as well! My favorites to start indoors are nasturtium, bee balm, and basil.

Other Seedling Planting Tips:

  • Before filling your containers, mix soil with some water first so that it's moist but not muddy. This will provide a good environment for your seeds to start so you won't risk washing them away. This can easily happen when watering dry soil.
  • Mind the instructions for seed planting depths. I've been somewhat haphazard in the past and have noticed that it definitely makes a difference in how seeds germinate and grow.
  • Plant 2–3 seeds per pot – some may be duds, and if not, they can be thinned or separated and replanted.
  • Label and date your containers! It's very easy to lose track of what's what once the seeds are planted. I use a sharpie and write directly on containers. Another option is to draw a diagram on paper.
  • If seedlings start looking “leggy,” as if they are working too hard to get enough sun, it's likely that they need more light regularly. This is often why gardeners choose artificial lighting. I've read that it's recommended to light seedlings for 15 hours per day!
  • Incorporating the use of a small fan helps keep your seedlings properly aerated once they've sprouted. Over watering your seedlings is very problematic. Try to keep your soil moist, but not soggy or muddy.
  • When seedlings look like they are outgrowing their pot but it's still too early in the season to plant outdoors, transplant them to a larger container so the roots have more room.
  • Before planting seedlings in a planter or garden space, they need to be introduced to the climate of the outdoors slowly. This is called “hardening off.” Give your seedlings short doses of the outdoors – a couple hours at a time, gradually longer over the course of a week to 10 days. An outdoor porch or cool garage works.

Many seeds for both vegetables and flowers are currently already available at the co-op. For those of you who prefer starter plants, be sure to mark your calendar for Mayfest, starting Friday May 12th, our annual plant sale kick off event!

By Alex Newby, Produce Lead • Photo retouching by Christine DeMars • March 2017