Given the right climate conditions carrots will readily germinate and grow in the open, but they will get a higher strike rate if they are covered in the early stages of their growth as this offers better moisture and temperature control. It also reduces the risk of damage caused by slugs and snails.
When carrot seeds are germinating and in their early small seedling stage of growth they are at their most vulnerable. If the soil dries out or soil temperatures drop too low at night there is a risk of damaging or even killing the seedlings. They are also very vulnerable to slug and snail damage at this early stage.
Covering your young emerging carrots creates a microclimate where the soil moisture and temperature levels are more stable. It also acts as a barrier between the carrots and marauding slugs and snails.
- COVER EACH ROW OF SOWN CARROT SEEDS WITH PLANKS OF WOOD OR THE ENTIRE BED WITH AN OLD SHEET OR TOWEL
- AFTER ABOUT A WEEK CHECK EACH DAY TO SEE IF THE CARROT SEEDS ARE PUSHING THROUGH THE SOIL. REMOVE THE PLANK OR SHEET ONCE THE EMERGING CARROT SEEDLINGS ARE CLEARLY VISIBLE
This method is the one used by traditional vegetable gardeners to germinate parsnip seed but it can also be applied to carrot seeds.
Its main disadvantage is that you cannot see the germinating carrot seeds without lifting the plank or sheet. You also must remove the plank or sheet as soon as the seedlings emerge to give them access to sunlight. When the carrot seedlings are just emerging is when they are most vulnerable to marauding slugs and snails
- PLACE LENGTHS OF 13 OR 19MM POLYPIPE ON TOP OF THE BED AT RIGHT ANGLES TO THE ROWS OF SOWN CARROT SEEDS
The polypipe is to keep the shade cloth slightly off the ground. The distance between each length of polypipe can vary, as long as it still supports the shade cloth. Sticks or lengths of wood can be used in place of polypipe.
- COVER WITH A LENGTH OF 50% SHADECLOTH
70% shade cloth can also be used but I have found 50% shade cloth to be better for vegetable gardening purposes.
- PIN THE EDGES OF THE SHADECLOTH WITH BIRD NETTING PINS SO THAT THE CLOTH IS STRETCHED TIGHTLY OVER THE POLYPIPE STICKS
Lengths of wood or star pickets can also be used to pin the shade cloth down. If there are lots of slugs and snails around then bury the edges of the shade cloth in the soil so that the emerging carrot seedlings are sealed in. Although pinning the shade cloth at the edges usually gives enough protection against slugs and snails.
- REMOVE THE SHADECLOTH WHEN THE CARROT SEEDLINGS ARE PUSHING UP AGAINST THE BOTTOM OF THE SHADECLOTH
By then the carrots should be big enough to withstand attacks from slugs and snails, though you may have to apply further protection measures if there are lots of slugs and snails around.
The main advantage of using shade cloth is that you can see the emerging carrot seedlings without having to remove the cloth. The gap that the polypipe sticks create means that the carrot seedlings can grow much larger before having to remove the shade cloth. The larger the seedlings the less vulnerable they are to marauding slugs and snails.
19 mm polypipe sticks covered by 50% shadecloth. The sticks offer a 2 cm space below the shadecloth for the seedlings to grow while the transparent nature of shadecloth allows you to monitor the growth of the seedlings without having to lift the shadecloth off. The edges can be pined down with bird netting pins or pieces of wood or metal. Pining the edges creates an effective barrier against marauding slugs and snails.
If the threat from slugs and snails is high, then bury the edges under the soil to completely seal off the carrot bed.