Posted on

How to Start Seeds Indoors: the Best Way to Start Seeds

Seeds growing indoors on a home-made light stand
Seeds growing indoors on a home-made light stand

Many beginner gardeners think that growing their own transplants – starting plants from seed and growing them on until they are ready to plant outside – is too hard. The truth is, if you have the right equipment and information, and you start with easy vegetable varieties, it’s not hard at all.

Why start plants from seed?

  • It’s far cheaper than buying seedlings if you want lots of plants
  • You can get many varieties which are not available at nurseries
  • You’ll have seedlings ready at a time which suits you
  • You can grow organic seedlings without paying a premium price for them

Seed-starting methods

There are many ways to start seeds and grow seedlings, some requiring more equipment than others.

Indoors – On a Windowsill

We don’t get enough winter sunlight here in the PNW to grow the best transplants this way, even with reflectors, but if it’s your only option you can do it. They will just be leggier than is ideal. If you live in a sunnier climate, you may find it works great for you.

Indoors – Using Grow Lights

  • Can produce excellent seedlings
  • Needs a certain amount of equipment, but not too expensive – you should be able to get started for $50 or less.
  • Needs about 2ft x 6ft floor space minimum


An unheated greenhouse can be used for starting hardy plants, and even tender ones if you heat a small area using heat mats or tapes. Temperature control can be awkward, as it can get too hot in the sun.

Soil for starting seeds

Don’t use plain garden soil! It compacts too easily in a small container and often either holds too little or too much water. It’s also likely to have weed seeds in it, which will compete with the plants you are trying to grow.

Requirements for Good Seed-Starting Soil

  • Fine texture
  • Holds water well
  • Drains easily

Home-made compost can be used as part of a seed-starting mix if you sterilize it first to get rid of weed seeds (pour boiling water over, or bake in the oven – very stinky!) and sift out all lumps. Mix with fine peat or coir, and perlite or vermiculite. It’s actually better used for making potting mix for potting on plants once they have germinated and grown into seedlings.


You don’t need any fertilizer for germination: the seed has its own food supply built in. After the seedling has 2-3 true leaves, you will need to feed it if it’s going to stay in the pot. Fertilize very sparingly using liquid fertilizer in the water.


Pretty much anything that will hold at least an inch depth of soil can be used.

Recycled containers

For example, yogurt pots, styrofoam cups, plastic cups, egg cartons, plastic bakery containers etc standing on waterproof trays. You do see pretty pictures of seedlings starting in half-eggshells but in practice they really don’t hold enough soil to be useful. Crush them and put them in the compost pile instead!

All containers must have drainage holes, so you may have to poke a hole in the bottom of each.

Cardboard tubes are handy for seeds with long taproots like peas, beans and corn. The outside of the tube may go moldy, but don’t worry – it doesn’t hurt the plants. You can plant these right into the soil when ready, tube and all, just like a peat pot.

Newspaper pots

There is a product called a Potmaker which helps you make small pots out of newspaper. It works fine, but it’s not really necessary. You can use a parallel-sided jar, can or glass to make them, with the advantage that you can make different sizes to suit your needs.

Tear or cut strips of newspaper, fold double, then roll newspaper round a small can or glass of the desired size, fold flaps under at the bottom and tape. Here’s a page with instructions for making newspaper pots.

New containers

You can buy plastic flats with inserts and lids at garden centers and these can be re-used multiple times before they start to break apart. If you have a choice, buy heavy-duty no-hole trays and they will last for years. Standard tray size is called “1020” because it’s about 10″ x 20″, and the inserts are made to fit the trays, so you can have from 12 to 288 plants growing in one tray!

There are many other more expensive commercial seed-starting kits and containers, but I’ve never found a need for them. Keeping to standard sizes is useful when buying more later on.

Peat and Other Decomposable Containers

These are recommended for plants which don’t like their roots disturbed when planting out. You plant the whole thing, pot with plant inside it. They now come made from coir (coconut fibre) or even cow manure, as well as peat. You can use newspaper pots or cardboard tubes instead.

If you do  use this type of pot, make sure they are very wet when planted out, and tear off rim so it doesn’t stick up above the soil.

Peat / Coir etc pellets

These are held together by a kind of netting on the outside. The netting is supposed to break down in the soil, but I’ve found it still there years later.  They are also “one size fits all” – bigger then needed for small plants, and too small for bigger plants. They seem convenient but I prefer not to use them.

Tools for sowing

Plain old fingers work for many seeds (depending on how small and nimble your fingers are!) but some small ones are easier to deal with using a tool. I’ve used many of those available, and I always go back to fingers or tapping the folded seed packet. You should try out different tools and see what works for you.

Where to do your seed-starting

For the actual planting you need a space where you can make some mess. Ideally it would have a hard floor, a work surface, and water available close by, so a basement, garage, kitchen, laundry room or even bathroom might be suitable. You can get planting trays with sides to corral the soil mess, if you have to do your planting in a clean space. A piece of tarp or plastic sheet with the corners folded up and held together works just as well, and can be folded up flat for storage.

If you’re going to use lights to grow your plants, you need somewhere to put the light stand. I have used a basement, home office, living room, stair landing, even a bedroom – though it turned me into an early riser when the lights came on at 6am!

Indoor Light Equipment

The basic need is for a surface to put the plants on, one or more light fixtures, and a structure to hold the lights over the plants. This can be anything from an expensive ready-made purpose-built light stand, to a home built structure from scrap materials.


The smallest practical setup uses a 2ft “Bright Stik” over a narrow shelf and a few plants. One Bright Stik will barely light one windowsill flat, you can’t replace tube, and it’s really not economical. However, if you already have one in the house you’re not using, go for it!

Shop Lights

These are usually 4ft long with two T8 fluorescent tubes, intended for lighting in workshops and garages. They are cheap and one will light up 2 regular size 1020 flats.

Don’t use incandescent grow lights – they don’t put out enough light and they  get too hot.

Fluorescent Grow Lights

These are similar to shop lights in size but use a narrower T5 tube which is brighter and has a better “color temperature” for plants. You don’t actually need the “full spectrum” tubes for growing seedlings, only if you want to grow plants to the flowering or fruiting stage under them. I find that one of these tubes replaces a 2-tube shop light.

LED Grow Lights

These can be the same size as the T5 fluorescents (so you can swap them out), or they also come in different sizes and shapes. They work very well. They are still about twice the price of fluorescent but are still coming down in cost.

High Intensity halide lights

Very expensive, only for serious growers – you can light a whole 4ft x 8ft grow table with one light.


Your lights must be turned on and off morning and evening. It’s way less hassle to put them on a timer than to try and remember to do it yourself. The lights should be on for 16-18 hours a day eg 6am – 11pm

Heating pads or cables

These are not necessary for most seeds, but if you are growing in a cool area like a basement, they can help a lot with heat lovers like peppers and basil.

You may be able to sit your tray of planted seeds on top of a water heater or fridge instead!

Fan for Intermittent breeze

The breeze from a fan helps seedlings to grow strong and stocky, and makes adjustment to outdoor conditions easier for them. You can have the fan on a timer as well as the lights and heating pads. Just use a regular oscillating table or floor-standing fan.

Shelves or supports

What do you already have? An old table with books or cement blocks to hold up the lights, a shelf unit (hang lights from the upper shelves), a space on your kitchen countertop.

If you want to grow more than a couple of flats, a light stand is very useful. It’s just a shelving unit sized and fitted to hold lights and plant trays.

Home made can be cheap and simple – I’m still using one I made 25 years ago that folds up for storage. You can download the plans here: Light Stand plans.

Commercial light stands are expensive: $170 – $500 and upwards. But if you have more money than time they may work for you.

How to Plant the Seeds

First, get everything ready:

  • Make sure any recycled or re-used containers are squeaky clean.
  • Damp the soil if it’s dry – not sopping wet, but damp like a wrung-out cloth.
  • Remove or break up any large lumps or objects like pieces of wood or stones in the soil – you don’t want them sitting on top of your seeds!
  • Some large, hard seeds, like peas and beans, can benefit from soaking beforehand. They don’t need it, but they will germinate quicker. Soak for about 8 hours or overnight in plenty of clean water.
  • Check seed packets for anything special your particular seeds may need you to do before planting.

Fill your containers:

  • Fill to the top with loose damp soil – don’t leave any big air spaces
  • Knock the container on the table to settle the soil
  • Make a dent in the top of the soil for the seed, if it’s larger than very tiny. You can use a pencil or a small stick for this. Make the dent big enough across to hold the seed(s) and about 4x as deep as the size of the seed.

Plant your seeds

How many should you sow? It depends on the seeds. if they are expensive hybrids, plant one per container. If they are brand new seed – one per container. For cheap or old seed, plant 2-3 per container.

Drop the right number of seeds into the dent you made in the soil. Jiggle the container to settle them into the soil. Small seeds don’t need any more covering than this, but larger seeds need to be covered with a bit more soil so they are under a layer about 2-3 times as thick as the seed is wide.

The smaller the seed, the shallower you sow. Tiny seeds may just be left on the surface. A few seeds need light to germinate and must not be covered (check the seed packet).

Now gently firm the soil over and around the seeds. Don’t squish down hard: all you’re trying to do is get good contact between the seed and the soil.


The important thing to remember here is that you don’t want to put lots of water on top of the container and flood the seeds out of place. Bottom watering is best – use a larger tray or sink and stand the container (which has holes in) in an inch or so of water to let it take up as much as it can. Then place it on an empty tray to drain. You can also use a mister or a fine spray bottle to wet the top of the soil, but the risk here is that the top layer may look damp while the soil lower down has dried out.

Once everything is planted and nicely wetted, cover the whole tray with a clear plastic cover. That can be a dome which fits a 1020 tray, a plastic bag, a clear bakery container, or anything else which will keep water vapor inside and let light in. You should not need to water again until the seeds sprout.

When Your Seeds Sprout

Once you see those little green shoots, it’s time to crack the lid open or open the plastic bag. Take several days to gradually give the seedlings less cover and more air. Once the clear top is completely removed, make sure to keep the soil damp (but not soggy) by bottom watering as necessary.

Some plants (like lettuce and the cabbage family (brassicas), can be planted out quite early in the spring so you can often plant them straight out from their first small containers, as small seedlings. Others, like tomatoes and peppers, will need to spend longer inside while the weather warms up, and you’ll need to “pot them on” into a larger container to keep growing.

Potting On (Re-potting)

3” or 4” round or square pots are a good size for potting on. Some plants don’t mind having their stems buried to reduce legginess (tomato, broccoli, lettuce) and potting on is a good time to do this. Seedlings to be re-potted should be watered and allowed to drain several hours beforehand, so they are thoroughly damp but not sodden.

Here’s what to do:

  • Prepare a larger pot with damp soil, and a hole for the seedling that’s about the same size as the root ball
  • If possible, squeeze the bottom of the container you want to get the plant out of, to loosen it
  • Cage your fingers over the soil in the rest of the container to stop it falling out
  • Turn the container upside down so the desired seedling slips out of the container into your fingers. You may need to shake gently, tap or squeeze to encourage the seedling out. Pushing with a pencil through a drainage hole can help.
  • Drop the seedling into the prepared hole
  • Firm soil gently around seedling
  • Water well from the bottom

I’ll be posting another article all about how to transplant your seedlings into the garden, so stay tuned for that!