Sowing in a seedbed

Sowing densities

Before sowing, it is necessary to discover the correct sowing density for the seeds to germinate and establish as healthy plants. It is as useless to sow too thinly and so waste space as it is to sow too thickly and have very small, useless seedlings that are liable to damp off. A desirable population will depend on the particular plant grown and its vigour.

Once the desired seedling density has been decided, this figure is modified by two factors which will then determine the number of seeds to be sown. The first is the viability of

SUITABLE SEEDING DENSITIES

Sow at 10-12 per square foot

Beech; Cherry; Chestnut; Nut; and Oak.

Sow at 18-22 per square foot

Crab apple; Maple; Rowan; Thorn; and

Whitebeam.

Sow at 25 per square foot Araucaria; Cotoneaster; Daphne; Dogwood; Hamamelis; Magnolia; Roses; Viburnum; and Vines.

Sow at 35 per square foot

Barberry; Holly, Mahonia; and Skimmia.

Sow at 50 per square foot

Abies; Cedrus; Picea; Pinus; and Rhododendron.

the seeds—that is the number of seeds that are alive and capable of producing new plants. Take a few seeds and, if possible, cut them open to see what percentage are viable. The second consideration that will affect the sowing density is a survival factor. As it is unlikely that all the live seeds will germinate and establish as seedlings, an estimate must be made of the likely losses, which may be caused by poor germination conditions, rots, pests and frost. In general, the larger the seed and the shorter the period between sowing and germination the greater chance it has of survival.

Sowing in a seedbed

Having arrived at a sowing rate and preferably on a still day, sow the seeds in the fine tilth of a well-prepared seedbed.

Station sow seeds that are large enough to be handled individually, spacing them evenly. To achieve an even distribution with smaller seeds, broadcast sow with your hand held just above the soil level so that bouncing is minimized. Once the seeds are sown, firm them into the seedbed so that there is intimate contact between seeds and soil and water uptake is enhanced. Then cover the seeds with grit, a shovelful at a time. Place the shovel as low over the seeds as possible,

Sow at 50 per square foot

Abies; Cedrus; Picea; Pinus; and Rhododendron.

Well Drained Seedbed

7 Broadcast sow seeds, keeping hand low to prevent bouncing the seeds.

8 Firm seeds into the soil using a presser board.

9 Cover seeds with ^in grit, using a shovel held low over the seedbed.

and then retract it quickly, leaving the grit on the seedbed. This method reduces the possibility of the seeds bouncing. The grit, which should be about \ in deep, will provide a well-drained surface that will allow even percolation of water through to the soil and absorb the impact of rain drops without caking and splashing: it will also keep the seeds well aerated and make it easy to remove weeds.

Finally, levej the grit with the back of a rake, clearly label the seedbed and water in if conditions are dry.

This seedbed with its grit covering will maintain the seeds for an extensive period despite exposure to all sorts of weather conditions.

Protecting the seedlings

When seeds germinate they will be exposed to a number of deleterious influences which may reduc^growth or even cause death. The chief of these ill-effects is wind, which causes stress in seedlings, reducing growth considerably. Watering will not necessarily alleviate the situation as the seedlings may not be able to take up water quickly enough to compensate for water lost. Therefore, shelter the seeds from wind by putting some 50 per cent permeable mesh round the seedbed.

As soon as the seedlings emerge and produce green leaves, they will need feeding with nitrogen and potash to supplement the phosphate already in the seedbed. Although these nutrients can be supplied by top dressing with a granular fertilizer, it is better regularly to use a proprietary brand of liquid fertilizer at the recommended rate, applying a small amount frequently.

Tree and shrub seedlings are extremely susceptible to damage from frost. In their natural habitat they would be protected by the woodland or scrub canopy, but in the seedbed they are completely exposed. Until the danger of frost damage is passed, therefore, they must be protected either by stretching netting with very small holes above the seedlings on a semi-permanent basis or by spreading newspaper on top of the seedlings on those nights when frost is anticipated.

In addition, it is vital to control pests and diseases such as greenfly, damping-off fungi and various mildews by spraying regularly with fungicides and pesticides.

If the seedbed has been prepared adequately then few weeds should be present in the bed. Wind-blown weed seeds, however, will appear and germinate in the grit. Pull these out while they are still small and their roots are in the grit rather than the soil.

10 Level the grit by striking over with back of rake. Label seedbed clearly.

11 Erect windbreak round seedbed to reduce speed of prevailing wind.

12 Cover seedlings with newspaper when spring frosts are expected.

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