The Gardeners Almanac

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My Back Garden

Seed Sowing Indoors


Related Links

Week Numbers

Coldframe

Collecting Seeds

Compost

Fertiliser

Frost

Hardening Off

Heating

Plug Plants

Seed Compost

Sowing programme

Stratification / Scarification

Watering

When to Propagate

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:



Click 'Related Links' 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;

Vending Cup
Vending Cups
Recycled Food container
Recycled Food container
2 sizes of bio-degradeable pots
Bio-degradeable pots
70 mm Square Plastic Pot
70mm Pots
Three sizes of plant trays
Full, Half and Quarter trays
4 punnets in standard full tray
Punnets
9 cell tray insert
9 Cell tray insert
24 Cell tray insert
24 Cell tray insert
84 Cell tray insert complete with lid & tray
84 Cell tray insert complete with lid & tray

Washed Trays

A number of washed pots

Washed Pots

Trays soaking in bins

Trays soaking in Bleach solution

 

 

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


 

 

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.

View of a plug plant

Plug ready for Potting on

Removing a plug from a plug tray

Removing Plug from cell

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!


Seeds in a saucer being lifted out with tweezers

Picking up seed with the aid of tweezers

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.

 

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.


View of sand& Peat compost mix

Example Mix

Tray wit measured quantities of Peat & Sand

M/P compost + Silver Sand
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;


View of some Perlite

Perlite

View  of some Vermiculite

Vermiculite

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.


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.

Three Sizes of Trays .
Three Sizes of Trays .
4 punnets in a tray
Punnet
24 cell tray insert
Cell Tray
24 cell tray insert
Select suitable sized container .
over-filled cell tray
Ovefill container with Seed Compost.
scraping off excess compost with a spatula
Scrape off excess Compost.
trayful of compost
Filled container
Tray of compacted Compost
Compacted compost
Watering 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!

Watering with a pump spray

Using a Pump Spray

Watering with a fine rosed watering can

Using a Fine Rose

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!


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.


Seed tray sitting in tray of water

Seed Container in water filled tray

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.


Watering with modified watering can

Controlled Watering

Nozzle fitted to reduce  diameter of watering can spout

Modified Watering Can

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

This gives 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.


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 teaspoon of silver sand into seed packet
Add silver sand to seed packet
Aternative: Add Teaspoon of Vermiculite to seed packet
Add fine vermiculite to seed packet
Add seed & sand to a n old condiment shaker
Place seed packet contents into shaker
Sow seed directly from packet
Sow Seed / Sand mixture
Sow seed directly from packet
Shake seeds onto Compost
Spraying water on to tray on completion
Lightly Spray Container

Alternative methods of spreading contents on to compost:


Covered tray on hotbed

Covered and on Hotbed

*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.


Sowing Small / Intermediate sized seeds:

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


Germinated seedlings

Germinated seeds

Sowing seed with a dispenser

Sowing seeds

A seed dispenser

Seed Dispenser

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.


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 dispenser 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:

Punnet filled with seed compost
Prepare container
Medium sized seed in seed  dispenser
Medium sized seeds
Sowing individual seeds using tweezers
Sow seeds individually
Seeds sown & labelled
Seeds sown & labelled
Various varieties sown & labelled
Various varieties sown & labelled
Sifting compost on to seeds
Sift compost over seeds
Seeds lightly covered
Seeds lightly covered
Pray water on to sown seeds
Lightly Water container
Tray ready for Propagation
Tray ready for Propagation
Tray covered ready for going on hotbed
Cover tray
Tray on the hotbed
Place tray on hot bed
View of germinated seedlings
One variety germiated
Sowing Large seeds:

Empty 9 cell tray insert
Select Container
Tray insert filled with seed compost
Tray filled with seed compost
View sowing a bean seed
Sow seed type 1
View sowing a sweet pea  seed
Sow seed type 2
View sowing a flat seed
Sow seed type 3
View of sown seeds
Seeds sown
Seeds covered with compost
Cover seeds with compost
Seeds watered & labelled
Seeds Watered & Labelled
A view of some germinated seedlings
One variety germinated
Propagation:

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

This information is generally written on the seed packet*

For example;


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;

View of quarter tray after seeds  are sown
Seeds sown on surface of Compost
View of pane of glass placed on top of tray
Glass Cover
View of the condensaton on the underside of the glass
Note the Condensation

Typical tray & cover arrangement

Covered Container

 

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.


 

Close up of some newly geminated seedlings

Germinated Seedlings
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.


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 view of punnets sub-divided with a marker

Sub-Divded Containers

Examples using square pots & trays

Pots close together

70mm square plant pot in storage tray

Approx 500 Pots in 750 mm wide tray

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.

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!