At this time of year we are all eager to start planting. There are a lot of good reasons to start early - not least the prospect of an early crop. But sometimes early sowing can simply result in spindly and weakened specimens. Those elongated specimens are suffering from a syndrome called 'etiolation'.
WHAT IT IS?
Etiolation is a lengthening of the first shoot. When a seed sprouts it sends out a sturdy shoot which pushes its way up through the soil. This shoot gets its energy from nutrients within the seed and by directly absorbed water. As yet the seed won't have developed a root system. So nutrients that may or may not be present in the soil are of no use to the shoot. The shoot is seeking sunlight. Once it breaks through the soil the first leaves will unfurl and photosynthesis can take place.
WHAT GOES WRONG?
But at this time of year two or three compounding issues can cause the seed to continue shooting without spreading its first leaves.
- Seeds sown too shallow
- Too much heat
- Not enough light
Etiolation is particularly associated with low light levels. At this time of year the length of the day is too short for many plants. The golden day is February 14th (Some coincidence I always think). On that day we start to get more than 10 hours of daylight.* The magic number of ten hours switches on sturdy growth in all sorts of seeds and plants. That day also signals the day when birds start to nest – hence its association with lovers.
People often blame the lack of light as critical element. But sowing a shallow seed and giving it too much heat can be as much to blame. In fact too much sunlaight (for less than ten hours a day) isn’t a huge help either.
WHAT TO DO?
Some gardening books will suggest throwing the seedlings away and starting again. But you will find that a bit of nurturing will bring them round. Once you understand that etiolation is effected by three separate functions you have a number of actions to take to rectify the situation.
- Give the seedlings better light
This might include thinning them, moving them to a better position, or simply opening the curtain earlier in the morning. A good supply of bright light, but not too much direct sunlight is best. - Reduce the heat
Sometimes the syndrome is caused by too much heat, which turns each little seedling into Superman. This can be a problem if you, like me, cultivate on a sunny windowsill in a living room or a warm kitchen. Consider moving the seed trays to a cooler site – perhaps in an east facing window instead of south facing. 10°C is the lowest level of heat that emerging seedlings should enjoy. Anything over 18-20°C at this time of year is a bit too much. - Add a little more soil.
The red chard seeds above were planted too shallow. I’m growing them as microveg and simply wanted the shoots, so I didn’t bother to follow the usual planting advice which is to plant about 2cm under the soil. I just sprinkled the seeds onto the soil mix and covered with a sheet of paper. So even though these seeds are suffering from etiolation, in fact the shoot isn’t really too long, it’s simply a case of too little soil. This can be easily rectified by sprinkling more soil on top and GENTLY bedding in the delicate shoots.
Gently is the operative word here. Before the shoots have developed leaves and roots you will have to touch the shoot itself. This is a very delicate at this stage – so take care.
Remember that in the wild plants come up against all sorts of problems and still manage to thrive. Unless you are growing for show, its worth making a few adjustments and hoping for the best. Most plants will recover.
I will update this blog when the seedlings are a bit larger, so you can see what happens.
* The start of spring light is slightly different depending on which part of the country you live in. It’s a day or so earlier further south in the UK and a day or two later in the north.
