The following is a guest post by Nev and Linda Sweeney from the wonderfully informative site Under the Choko Tree.
There are a whole stack of reasons why it is worth raising your own seedlings rather than just buying them –
It’s very satisfying and fun to raise seedlings – if you like growing veggies and enjoy the charge you get out of eating something you have grown, how much bigger a charge will it be knowing that you took the process from seed to plate?
Raising your own seedlings is economical – back in the day, I used to spend lots of money, sometimes up to 40c or so per seedling, a cost you rarely notice but believe me it adds up. I had to wait until payday before I could stock up on seedlings! Growing your own means they cost less than a tenth the cost of the commercial ones especially if you use the process I do.
Wider variety of vegetables available – get hold of a seed catalogue and you will see that there are a huge number of open pollinated and heritage seeds that are available, of which 10% or less would be available if you buy your seedlings from a nursery or hardware shop.
Efficiency – you only put in plants that have germinated, otherwise you may plant out a whole load of seed and only get a few plants up.
Headstart – The plant you put in are up and growing, with a jump on pests and diseases.
Better Germination – you have more control over the germination conditions
If I have convinced you, great! Now read through the rest of this article and see the tried and true process I use to grow my seedlings.
I have a world class collection of plastic plant containers! They are all left over from when I used to buy seedlings from the nursery and before I realized how easy they are to raise yourself. I use the ones with six or eight divisions in them, although for larger seeds like pumpkin I still use the older style with no divisions. If you are re-using your seedling containers you should wash them in disinfectant and dry them off before you use them. This is to prevent a build up of disease, I usually use one of the “el cheapo” ammonium disinfectants available from the supermarket.
To fill the seedling containers, I make a seed raising mixture that it composed of –
– 3 Parts by volume of cocopeat or horticultural coir
– 2 Parts by volume of sieved (and preferably home produced) compost or worm castings*
– 1 Part by volume coarse sand
*Some time ago I was using the compost exclusively, and while being stored in the greenhouse it got a bit of heat treatment which may have killed off any pathogens. Later, I started to get problems with the seedlings keeling over from damping off and changed over to the worm castings. The damping off has not returned so you may take what you will from that.
The compost/worm castings give some nutrition and body to the mix, the cocopeat ensures water retention and the sand ensures drainage. I was adding one part of perlite to the mix, but it was expensive so I left it out and the response seems to be the same. I use a 500ml plastic Chinese food container as a measure. All of this is placed that wonderful product, the cat litter tray – cheap, available and mind bogglingly useful, more on them later. Mix by hand and voila! Homemade seed raising mixture.
To use your homemade potting mix, place it in the plastic seedling container and firm it down, leaving a small depression in the centre of each division. Place a few seeds into the depression and add a light cover of potting mix over the top and press down gently to give good soil to seed contact.
The surface should be flush with the lip of the container so that there is good air drainage, otherwise still, moist air can favour damping off, a fungus which causes the new seedling to look pinched where they emerges from the soil, killing them. Label the division with a tag (These can be cut from an ice cream carton with scissors) showing the vegetable type, variety and sowing date.
Follow this process for the rest of the tray divisions.
Once the tray is full it needs to be kept warm and moist until the seeds germinate, but watering from the top can wash the seeds out of the seed raising mix so they need to be watered from underneath.
The easiest way to do this is to make a capillary bed by getting one of the aforementioned cat litter trays and half filling it with coarse sand (fine sand will crust over) I use the same sand I add to the seed raising mix. Place the tray/pot(s) on the sand and then water the sand until there is just a little free water over the top of the sand. The seed rasing mixture in the pots will absorb the water by capillary action eliminating the need to water the seedlings directly and the sand will form a reservoir of water reducing the amount of the attention needed by the seedlings. In hot weather, place the capillary set up under some shade cloth. In cold weather, make a small plastic house, green house or cold frame to keep the seedlings warm.
Once the seedling has grown to the four leaf stage, it can be potted on into a larger single container to grow on further until you are ready to plant it out into the veggie bed. I used to do this by making up a potting mix that is a bit richer than the seed raising mix –
– 1 part by volume of coarse sand
– 2 parts by volume cocopeat
– 3 parts by volume sieved compost
But I found the original seed raising mix worked just as well so I now use that mix for both operations.
I pot the seedlings on into 100mm lengths of cardboard tube that I get from work (They are the spool around which paper for the plotter is wound) which used to be thrown out. You could use toilet roll inserts or make them out of newspaper. Originally I coated them in wax and the used a wooden slug to push the seedling out so that the tubes were re-useable, but I found that the transplanting shock for the seedling was considerable and after 2 or 3 uses the tubes carried all sorts of bugs that caused damping off etc. anyway. Now they are uncoated and single use only, rotting down to allow the roots out into the soil over time.
To pot the seedlings on I fill a tube with the potting mix then push a hole down the centre of the mix in the tube with my finger. I then dig the seedling(s) out of the punnet with my space age technical potting tool (a paddle pop stick). In most cases you will have more than one seedling so pick the largest and strongest ones to pot on, keeping as much of the seed raising mixture around the roots as you can. Place the seedling gently into the tube, while using the potting tool to push the potting mix firmly around the roots. I then top the tube up to level with the edge and place it in a plastic flat (designed for holding punnets) which holds 16 to 20 tubes. The flat and tubes then get placed onto another capillary bed to be kept moist until they are ready for planting out.
This process works well for many seeds although some seeds like root crops such as carrot and turnip still benefit from broadcasting into where they are going to grow and some larger seeds like beans and peas are just as easy to direct sow as well.
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