As we move into the start of the autumn, I know – it is only half way through August but the weather has changed, I usually start to sow seed for late autumn/winter.  I thought I would do a small trial about methods of sowing because I have changed how I sow and I am not sure that it is any better.  Time to look more closely.

I have sown a variety of seed in three different ways:

1. into trays for potting on
2. into cells where the seeds stay until there is space to plant out
3. into soil blocks until there is space to plant out.

One thing I have done is change my sowing medium. This year I have been using Sylvan compost or ‘growing medium’ as they call it. The conclusion I have come to is that there is not enough ‘food’ in this medium to sustain seeds for the length of time that I need to keep them. It’s a shame because the germination rate is good. So, I have gone for a general compost with a bit of sylvan compost mixed in.

I have sown the following seeds. They should give a good indication for a much wider range of vegetables at this time of year:

1. spinach: medania
2. rocket: Jekka McVicar rocket that was free with a gardening magazine
3. choy sum: this is quite old seed so it might not germinate well
4. april: a good basic cabbage for early next year
5. red frills: a mustard for salads over winter
6. beetroot – boldor: a yellow beetroot. I didn’t sow this for transplanting as this would not suit the vegetable.
7. Treviso and pallo rossa: chicories for early next year

Sowing in trays and cells is very common. Fewer people use soil blocks.  They are made with a trusty soil blocker. I bought mine about 18 years ago from Organic Gardening and makes 4 blocks 5cm by 5cm. I do like the look of the larger block which this block fits into but I reckon you would only need it for tomatoes and squash so it is probably not worth getting.

Mix compost with water to make a wet mud pie

Push the soil blocker down and compress the compost into the blocker

Press the lever down to release the blocks

Voila! Blocks with a depression to sow into

And here they all are on in the greenhouse.  The soil blocks are covered in black plastic until the seeds germinate and then it is removed: the seeds are not covered in compost. Those in the trays and cells are covered in a light layer of compost.  

The disadvantage of the soil blocks are the time it takes when sowing to make the block but that time may be made up if seeds because the seedlings don’t need to be potted on.  The advantages are that the compost contains more water than the other two methods which may mean faster germination and I find them the easiest to get out of the tray to plant.

The advantages of the cells are that they are very quick to sow and stay there until planting so no further work needed. The disadvantage is that I find them really difficult to get out of the cells and often split them or break the roots.

The disadvantage of sowing into trays is that there is more work to transplant them before planting out but I do think that the transplanting seems to benefit the seedlings, making them stronger and providing fresh compost and space to grow into.

The cells and blocks are very economical with seeds. I put two seeds into each cell or block where as I tend to end up with a few seedlings left over when sowing into trays.

What I am interested in knowing is what is the quickest method for sowing and planting out that leads to the strongest seedlings that take off as soon as they are in the soil.  I will keep you updated.

Have you undertaken any trials this year?  What happened?

Seed sowing trial update 1

Seed sowing trial update 2