Seed Sowing Indoors

 


Overview:

Seed sowing is probably one of the more satisfying and rewarding parts of gardening, and it is even more rewarding if everything goes to plan!

This article has been written to to show you how to make this plan.


Planning:


Having a sowing plan prior to starting up your sowing programme can be very useful, particularly if you are going to be sowing many seed varieties.

For example; a plan can save you lots of time and expense in the long term.


Here are a few things to consider when making a plan:


Knowing this will indicate which varieties require heat, and which ones dont, it will also allow you to utilise your heated / frost free space more efficiently.

Remember! The more half hardies you grow the more heated space you will need.

What is the point of growing more than you require? plus surplus plants will take up heated / frost free space that may be needed for the plants you actually need!

A knowledge of approximate germination times* can help you stagger your sowing dates, thus allowing you to utilise your heated space better.

* Many of these can be found elsewhere on the website.


Once you have created your sowing plan, sort out your seed packets into their order of sowing.
Seeds stored in Sowing Order

Do you have sufficient frost free space to harden off your plants in until planting out time?

Each seed variety is usually in the heated area for a few days/weeks, whereas plants that are hardening off in a cooler environment could be there for two or three months!

In some respects this need is more important than the amount of heated space you have, for example;

For example: do you have a Cold frame, Cool greenhouse or Conservatory?

Frost Protected Shelving
Coldframe for hardening off

Click here for more planning information.


Equipment:


The first thing/s you will need is container/s to sow your seeds into, basically any container that is clean, has a few holes in the bottom, and will hold compost will do.

For exanple; you could use recycled vending cups, cartons, trays that have contained foodstuff, or you could use purpose made products.

The pros and cons with these are;

This could cause them to become brittle and fall apart at a most inopportune moment.

Here are a few examples;

Vending Cup
70mm Pot
Half pot / pan
Fibre pots

Food container
Full, Half and Quarter trays
Punnet

9 Cell tray insert
24 Cell tray insert
96 Cell tray insert

To reduce the risk of diseases being transmitted to the new seedlings, ensure that the containers are cleaned prior to using them!

Washed Pots
Washed Trays

Cell/ Plug trays


In recent years, cell/ plug trays have become quite popular as amateur growers follow the practices of the commercial growers.

Unlike the commercial growers who have mechanical means of sowing seed, the amateur has to do this by hand which can be quite time consuming.

However! In the longer term this can still have its advantages, for example; at the pricking out stage, the seedlings are effectively already pricked out.


That is, the plugs can be extracted from the cell tray and potted on with a minimum of root disturbance.

This lack of root disturbance means the seedlings are not checked like they would have been using traditional sowing and pricking out methods.

As a result of this, they develop much more quickly after they have been potted on!

Removing Plug
Ready for Potting on

As mentioned above the commercial growers have mechanical means which will even sow individual dust sized seed into a cell, something the amateur is unlikely to be able to replicate.

Having said that the amateur can sow relatively small seeds with the aid of tweezers.

This method of sowing seeds can also make a saving in seed usage as it allows you to sow just enough seeds for your needs.

Picking up seed with the
aid of tweezers

Compost:

Idealy use a proprietary seed compost as this has been designed with reduced* quantities of fertilser in it.

*Too high a fertiliser content at this stage could be detrimental to the seedlings.


As an alternative to proprietary seed compost, you could use a proprietary multi-purpose compost that has been diluted with other ingredients to reduce the fertiliser ratio.


Method:


Measure out one measure of multi-purpose compost and an equal measure of silver sand* and mix them together.

The size of measuring container is subject to the amount of seed compost you wich to produce for example;

A one litre plant pot would be suitable for small quantities, or a ten litre bucket for larger quantities.


*Alternative additives can be used in lieu of Silver Sand.

For example; River (Sharp) Sand, Vermiculite,or Perlite.


Click here for more information on compost.

M-P compost + Silver Sand
Example Mix
Vermiculite
Perlite

Seed Sowing:

As a general rule seed can be considered to be of four sizes; Dust - Small - Medium - Large, consequently this gives rise to at least four ways of sowing.


Filling the container:


No matter which type / size of container you use, or which size of seeds you are sowing, the method of filling the container with compost is basically the same same e.g.


* Some people use some form of tamper to compact the compost the choice is yours! .

However;the writer considers that when the compost is tapped on the bench, then watered this should give all the compaction that is needed!


Select Container
Overfill it with Compost
Scrape off excess compost

Filled container
Compacted compost
Water compost (optional at this stage)

Watering:


This is another area that can be a matter of choice, i.e. do you do it before, or after sowing the seeds?

The writers choice is to let the type of seeds being sown dictate the timing of this!

That is, if sowing dust sized seeds water the compost before sowing the seeds.

This avoids the possibility of washing the seeds to one or more edges of the container.

Conversely, with larger seeds it is less messy to water after the seeds have been sown, plus when the water is added the water washes the fine material (sand) around the seed ensuring that the whole surface of the seeds is in contact with moist compost.

In the end the choice is yours! So do what feels best for you!


Method:


Like many things in gardening there is often a number of ways to carry out certain tasks and watering is no exception!

For example;

When watering either before or after sowing seed, one should use a fine rosed watering can to apply the water.

The reason for this is, the fine spray is less likely to disturb the compost and indeed the seeds if you are watering after they have been sown.

Alternatively, use a pump spray if you want an even finer applicator.

This method is particularly useful when watering surface sown seeds!

Using a Fine Rose
Using a Pump Spray

Similarly, a pump spray is useful tool to use once the seeds have germinated but are not quite ready for pricking out.

That is, when watering, fill the sprayer with a solution of clean water and a proprietary fungicide and this will help to prevent the seedlings damping off.


Placing the seed container in a bowl / tray of water is a method that can be used either before or after sowing.

To do this ensure that the water in the bowl / tray is not deeper than the container is high.

Place the seed container in the water and allow the water to seep through the compost until it is thoroughly wet*.

*This is seen as a darkening of the compost surface.

Seed Container in water filled tray

Another useful method is, fit a nozzle from a mastic/silicone tube to a small watering can in lieu of the rose.

This allows better control when watering individual cells / plants, and eliminates the over-spray you get from a rose.


This is also useful method to use after pricking out, as it means one can water the soil around the seedlings without touching the leaves, thus reducing the chances of damping off.

Modified Watering Can
Controlled Watering


Seed Sowing


Sowing dust sized seeds:


Select a a suitable sized container and fill it with seed compost and water it as described above.

Place the seed and a teaspoonful of dry silver sand*, or fine vermiculite into a salt shaker then shake the contents onto the surface of the compost.

Alternatively; add the silver sand, or fine vermiculite to the seed packet and shake it well to mix the contents together, then sprinkle the mixture onto the surface of the compost either directly from the seed packet or from an applicator.


Add silver sand to seed packet
Add vermiculite to seed packet
Place seed packet contents into shaker

Alternative methods of spreading contents on to compost

*Adding the sand allows you see that you are spreading the seed / sand / vermiculite evenly over the compost.

As a general rule dust sized seed do not require covering with compost i.e. they are sown on the surface and, as in this case, the silver sand, or vermiculite will give all the covering that is required.


Lightly spray the surface of the container with a pump spray to moisten the sand / vermiculite.


Cover the container and place it in a propagator, or some such heat source.

Lightly Spray Seeds
Covered and on Hotbed


Sowing Small / Intermediate sized seeds:


These seed are generally too large to use the shaker method or too small to use tweezers.


Select a a suitable sized container and fill it with seed compost and water it as described above.

If using a cell tray place a pinch of seed in each cell and lightly cover*

*Use vermiculite if the seeds require to be sown on the surface or sifted seed compost if they require covering.

Sowing seeds
Germinated seeds

If using a pot / pan / tray spread the seed thinly over the compost and lightly cover with sifted seed compost.

Alternatively you could place a few seeds in an applicator along with some silver sand or vermiculite and sow a pinch of seed to each cell, or spread evenly over the compost if using a pot / pan / tray.


Sowing Medium sized seeds:


Select a a suitable sized container and fill it with seed compost and water it as described above. (pic 1)

Using tweezers pick up a seed and place it onto the surface of compost, taking care not to squeeze or damage the seed.(pic 3)

Alternatively;use a purpose made seed sower/applicator. (2)

Alternative methods:


Lightly cover the seeds with sifted seed compost or fine vermiculite on completion. (pic 6)

1) Prepare container
2) Medium sized seeds
3) Sow seeds individually

4) Seeds sown & labelled
5) All varieties sown & labelled
6) Sift compost over seeds

7) Seeds covered
8) Lightly Water container
9) Tray ready for Propagation

10) Cover tray
11) Place tray on hot bed
12) One variety germiated

Sowing Large seeds:


Select a a suitable sized container and fill it with seed compost and water it as described above. (Pics 1 & 2)

This size of seed can be sown in a similar manner to medium sized seeds or alternatively use your fingers to pick up the seeds.(Pics 3,4,5 &6)

Once sown cover where applicable with vermiculite or sifted seed compost. (Pic 7)

Flat seeds should be sown on edge!

1) Select Container
2) Tray filled with seed compost
3) Sow seed type 1

4) Sow seed type 2
5) Sow seed type 3
6) Seeds sown

7) Cover seeds with compost
8) Seeds Watered & Labelled
9) One type germinated


Propagation:


Some varieties of seed may require particular treatments to aid germination.

This information is generally written on the seed packet*

For example;

Cover these seeds with vermiculite, this will allow light through to the seeds plus it will hold the seed in place until they germinate.

This covering will hold the seeds in place until such times as they take root into the compost below.


Stratification:


Click here for more information.


Other aids to germination:


Depending upon your source of heat you may have to do one or more of the following tasks;

Subject to the heat generated you may find that you have to regularly (daily) clear away any condensation that has formed on the inner surface of the polythene bag.


Quarter Tray
Tray filled with seed compost
Glass Cover
Note the Condensation

As with the polythene bag, the condensation that forms on the glass will have to be removed regularly (daily).

If using a purpose made propagator place the seed container/s in it, then replace the lid, and again regularly(daily) remove any condensation that forms on the lid.

Do the same if using a purpose made tray cover.

Covered Container

After germination:


As soon as seeds germinate remove the covering and place the container where it gets plenty of light (but not direct sunlight) and maintain a minimum temperature of 5-10C (40-50F).

If using a purpose made propagator, remove seedlings from propagator and place the container/s on hot bed or in a well lit area where you can maintain a temperature of 5-10C (40-50F).


Turning the containers regularly will prevent seedlings becoming drawn and leggy

Germinated Seedlings

Feeding.


Once a seed has germinated, an adequate supply of food is required to maintain continuous growth.

Each seed contains within itself sufficient nutrients to feed the initial growth of the first shoot.

In some cases this in built store can sustain the seedling until it can be pricked out into a compost containing more nutrients.


At other times; it may be necessary to supplement this feeding until such times as the seedlings are of a size to be pricked out.

This can be administered by means of a half strength* balanced liquid feed!

* Check the mixing instructions on the packaging for a full strength mix and halve this!

Do not be tempted to up the dosage, as this may do more damage to the seedlings than what no feeding at all would have done.


A Few Tips


Using square pots rather than round ones can take up less space when full (or empty).

Watering is more efficient because there are no gaps between pots as there are with round pots.

Filled Pots
Approx 500 Pots in 750 mm wide tray

When sowing seeds in trays, use quarter trays (160x90mm) or divide half trays into two, or full trays into four by means of plant label/s or a piece/s of split cane. (Punnets are a useful alternative)

This saves on compost and heated space

Sub-Divded Containers

Top of the Page