Starting Seeds Soilless

Information and photos provided by Neville Dearden

As most gardeners know, “damping off” is a fungus that spreads across damp soil and is particularly fond of consuming seedling tissue. Commercial growers, who could be seriously damaged by this disease, have developed soil-less techniques for seed germination that can be completed in sterile conditions.

As many of our more delicate species are successfully reared without soil than are reared with it, I fearlessly decided to put my skills to the test. I am now delighted to be able to walk you through the process and to share the results with you.

Soilless Seed StartingMaterials you will need:

Sowing without soil could not be easier as it is a very clean process. It is essential that this cleanliness be constantly maintained if success is the goal. The brug seeds are sown into Rockwool growing cubes, such as those illustrated. These can be purchased from good horticultural merchants or over the Web. Just one type is illustrated but there are others. The important thing is to be sure to obtain the smallest cubes you can, for after germination the rockwool becomes a nuisance which you will want to see the back of! The growing medium illustrated are three quarters of an inch cubes. You can also buy rockwool cubes individually wrapped in a film which prevents excessive moisture evaporation and these are well worth trying if seeds are to be germinated in an otherwise warm dry atmosphere or if regular attention cannot be given during the germination period. You will also require something to cut the rockwool; scissors or a sharp blade will do, also something to encourage the seed to sit well down into this growing medium. (I used a blunted wooden cocktail stick). I like to chit (peel) my seed for which the sharp blade was also used. Finally, a clean plastic container with pure water is needed to moisten the rockwool. The basic materials are illustrated in picture 1.

Cut the rockwool to help in identifying your seedsCut the rockwool to help in identifying your seeds

(Seeds illustrated were kindly supplied by Ludger Schneider) Cut the rockwool to help in identifying your seeds. With everything in hand, cut the rockwool into sections. Each section should have as many cubes as the number of seeds of each variety being sown. Cutting can easily be accomplished with scissors or a sharp blade as shown in illustration 2.

Moisture for germination

Brug seeds, like all others, will only grow if they have sufficient warmth, an adequate supply of air, and have access to sufficient moisture. Rockwool is a very effective thermal insulator and cushions the seeds against short term extremes of temperature. It is a very porous material which permits a relatively large amount of air to be retained within it. Indeed, it is that air that makes rockwool such an excellent thermal insulation material. In satisfaction of the need for access to water, this air can be partially or totally displaced by water. This latter characteristic of rockwool requires the greatest care in practice if brugs are to grow rather than rot. Too much water and the seeds will certainly rot; too little and they simply will not grow.

To achieve a satisfactory state of dampness a quick immersion of the lower half of the block of cubes in pure clean water should be followed by a very careful compression of the cubes. Compression to about three quarters of their original volume by squeezing the rockwool parallel to the direction of its grain will do the trick. (Rockwool fibers are directional and compress easily parallel to their grain but less easily along their grain). If you have any doubt about the quality of your water supply then use boiled or, better still, distilled water.

The initial watering is shown in the illustration and, although the water has rapidly soaked up the rockwool you can see that the water had not reached the top surface before the blocks were removed. (Note the colour difference between the dry and the watered parts of the cubes).

Sowing the seeds

In the next illustration individual seeds are being placed into the pre-formed slots in the top surface of the rockwool medium. In this example, the seeds are also being stripped of their corks prior to sowing. Note that the label for this block of seeds is already in place.

Seed preparation and sowing – Embedding into the rockwool

Once all seeds are in place they are gently eased down into the pre-formed slot in each rockwool cube. The tool being used here is a wooden cocktail stick with one end cut square to ensure no point pressure is applied to the seed.

In this view the lack of distortion of the rockwool is clear; a good indication that only sufficient water has been applied to wet the medium and insufficient to waterlog it.

Note the condition of the rockwool. It is not wet enough to leave water on the table even where pressure is being applied. A good guide to the degree of dampness is also seen by the colour comparison with the new medium beside that in which seeds are being sown.

The seed shown earlier was being prepared for sowing by remove the cork with finger-nails. This exposure of the seed from its immediate covering is known as chitting. Those in the following illustration are less accommodating, requiring a sharp blade and great care to remove their cork. Some prefer to leave the cork in place and which method is used is down to personal preference.

Once sown in the rockwool, seeds are transferred to a temperature controlled propagator such as the one shown in the illustration. Note that the rockwool shows no sign of excessive watering and that the propagator is thoroughly clean. If the propagator has been used for soil based cultivation it must be thoroughly scrubbed out prior to soil-less germination. Subsequent watering is undertaken using a fine sprayer. The cubes must neither dry nor become saturated.

Germination at last

Almost five weeks to the day the seeds start to show themselves. Note that almost all the rockwool cubes have a plant that is either showing its first leaves up or is emerging from the pre-formed slot in its cube. Roots also can be seen on the green plastic between the two blocks of seedlings. In the section of blocks illustrated every seed germinated without loss. As soon as the seed leaves are fully extended the cube containing the plant is cut away from the rest and potted up into soil based compost.

Birth of new seedling Brugs! One week later

Potting up is carried out into a compost consisting of soil based John Innes number 2 compost mixed with a slow release fertiliser, (I use “Osmocote” though others will probably work equally well). Also mixed with the compost is around 15% of its volume of perlite granules. These both retain moisture and considerably increase the ability of the soil to drain. In the US, use your preferred well draining soil mix. Note the seed has been planted complete with the rockwool cube making root disturbance minimal. Never-the-less it is recommended that excess rockwool is very carefully teased away from the cube immediately prior to potting to ensure the tendency of the rockwool to retain moisture does not result in subsequent damage to the seedling. It must be stressed that great care is needed to ensure roots are not damaged during this operation. If in doubt, plant the complete cube and water very carefully until the plants are well established.

Healthy young Brugs germinated without soil

Growing Brugs without soil was an interesting experience which I am pleased to share with you. I will certainly use the technique again though not exclusively. If the grower has the time to carefully look after the process then the seedlings grown this way quickly develop a good root structure which can be further improved by using a hydroponics liquid feed, carefully applied after the first seed leaves have developed. Is it now time to accept the next challenge and grow and flower the first fully hydroponically cultivated brug?