March 17, 2024

Why won’t my seeds germinate?

It is that time of year here in the UK and the sowing of seeds has begun in anticipation of a garden full of food during the summer.  There is nothing better than the feelings I get when the first shoots of green can be seen. Every year I get messages from people in my Facebook group frustrated because their seeds are not germinating.  I therefore thought that I would write about some of the reasons why this might be happening.

  1.  Over watering or underwatering.  The seeds need to be kept damp but if you over water the compost they can rot or become mouldy but if you do not water the compost enough they will not germinate at all.  I tend to germinate mine with plastic lids on or cling film so that they do not dry out but I don’t have to water very much.
  2.  Old seeds.   The date that seeds are viable will be on the back of the packet. I will hold my hands up and admit that I do use out of date seeds sometimes but I know that they might not germinate.  I do often still get 30% of them sprouting, though.  One way to test if the seeds are still viable is to put them in a bowl of water for about 3 or 4 hours.  If they sink they should be ok,  The seeds that have sunk need planting straight away.  Another way is to see if they sprout in damp kitchen paper.
  3.  Seeds planted at the wrong depth in the soil.  If a seed is planted too deeply into the compost it can delay the germination of the seed, or stop it at all as it runs out of energy trying to break through so much soil.  If the seed is planted too near the surface of the soil it might not get enough moisture or may be eaten by insects or mice.  The depth that a seed should be planted will be on the back of a packet of seeds.  If they are saved seeds the advice is that you should plant the seed at a depth of two times it’s width.
  4. The temperature.  Living in Yorkshire it can be cold during spring which is not good for seed germination.  Seeds need a temperature of between 20C and 30C to germinate.  Seeds can still sometimes germinate under this temperature but it will take them longer.  I use a heat mat to encourage my seeds to germinate.
  5. Poor quality soil.  Seeds need nutrients, moisture and air to germinate and so if the soil is too compact or old it is not a good growing medium.  If the seeds do germinate the plants will probably be weaker.  I don’t buy seed compost as it is expensive but I use new bought compost to grow seeds in my house as I do not want all the creepy crawlies running around that are evident in my home made compost.
  6.  Over crowding.  I often plant too many lettuce seeds together and so I prick them out and transplant them in a larger area.  When seeds are over crowded they fight for the nutrition in the soil and so the result is weaker plants.  They also compete for water and the over crowding means a lack of air and so the small seedlings can go mouldy.
  7.  Not soaking some seeds first.  Some seeds such as peas germinate more easily if they have been soaked for a while first before planting.
  8. Too light.  Some flowering seeds need darkness to germinate, for example delphinium.  Always check the back of the packet.
  9. Neglect. Seedlings are fragile and need attention and looking after.  This might include keeping them damp, keeping them warm, and making sure that they have enough light.  Conditions change, especially in early spring when it can still become quite cold.
  10. Seeds being stored wrong.  Always look on the back of the packet to see how the seeds should be stored as some do not like cold rooms and some do not like heat or damp.

Last year I had some old cucumber seeds that did not germinate.  I tossed the old grape punnet that they had been sown in onto a shelf in my greenhouse with the thought of using the soil later to top up my tomato plants when they were transplanted.  Two months later I looked on the shelf and I had about 9 small cucumber plants.  I can’t have had the seeds warm enough as they had germinated once the greenhouse warmed up.  Luckily I have a leak in my greenhouse and the humidity had kept them moist enough.

How is your spring sowing going?  Do you have many seedlings yet?  It is still early in some part of the UK.

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