I bought some new seedling trays and pots to try for growing and starting vegetable seeds off this year. One set were some tiny fiber pots that I've decided I'm not particularly keen on using. The other set was a plastic Gardman windowsill kit that comes with 3 parts to it consisting of a bottom tray, cell inserts and clear lid cover.
The Gardman seed tray is a long, rectangular design which measures 56 x 16 cm. This tray is to start seeds indoors on a windowsill where they can catch some sun and grow. Although you can use this item indoors, it can also be put outdoors which is how I've used it. I alternated between having this left outside on a table and inside the polytunnel (without the use of the lid) when the weather has been bad.
Description of the Seed Starter Set
Each set consists of 3 parts. There is a bottom tray which is particularly ideal for indoor use as it collects any water leaking out from the cells. There is the interior section of small cell modules; in mine there are 36 which you can split into half along a perforated edge. Lastly, there is a clear lid which sits on top. Each growing cell or pot is approx 4 x 4 cm in size. I've been sowing 2 or 3 seeds to each one and pricking out the weakest seedlings that germinate.
It's plastic and not everyone loves this as a material but I prefer these to the fiber pots I bought which seem to dry the soil out much quicker. The bottom tray is reasonably sturdy and necessary for growing indoors where you don't want water spilling out from the bottom of your plant containers. The clear lids are slightly less rigid and more prone to a bit of crumpling around the corners but they have not split or broken. They perch over the top of the tray which is fine for indoor use but for outdoor use, and particularly if windy, you may want to secure the lids with twine or elastic.
The interior cell modules or pots are the most flimsy part and particularly the bottoms of these which have holes in for the water to pass through. With care, I think I can get two or even three uses from each.
You need to take care getting the seedlings out when potting on and it helps to make sure the compost is nice and damp first. There are plenty of cells in a pack for starting seeds off and it is handily perforated down the middle if you don't need to grow that much at once. I also cut mine down further as I was growing swede and turnip seeds at the same time. You just need to take care cutting these down that the pots don't split.
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It Works Like a Mini Greenhouse
The key thing to remember with this type of seedling kit is to remove the cover often when you see too much moisture build up inside the lid. This will help to get adequate ventilation inside.
The lid is great as it acts like a mini greenhouse making a nice warm and sheltered environment. It also keeps the soil moist which aids germination and growth. However, you also need air flow or you risk the seedlings getting damping off disease which will destroy them. It's recommended to stop using the cover once the seedlings have sprouted and started to germinate. 
The lid is also useful if you are using this outdoors and it helps to protect the seeds from pigeons and other birds eating them as they grow. The important point to remember is to take the lid off periodically and especially once the seeds have started to germinate. Otherwise you could be creating an environment which is simply too damp.
Seedlings Growing and Germination
Here I have turnip seedlings and the slower growing swede which were both planted and sown at the same time. The turnips are several days ahead of the swede. Most cells had two seeds sown in them. I prick out the weakest growing ones although, if I'm careful, I may get away with potting on two from one cell if they're not growing too close together.
I've been thrilled at using this Gardman kit and how much easier it is to grow seeds when they are neatly spaced from the start instead of just scattered in a tray or container. The scatter method for sowing is harder when it comes to pricking out and potting on. This whole seed starter set has made it easier for me.
In terms of watering, I watered the soil well before the seeds went in and let it drip out until it was all nice and damp but not overflowing with water. Then I sowed the seeds and water with a fine mist from a spray bottle as needed which is normally 2-3 times per day. This is a great tip that I read online and it has stopped me from watering the seedlings too much. They need moist soil but not completely wet and saturated.
Using the Starter Kits Inside a Polytunnel
Here's the inside of my polytunnel. At this point, we had some really bad summer weather which was particularly cold for this time of year and came with constant rain. I used the seed starter kits in here on the shelving where they had protection from the bad weather.
I moved the Gardener's Delight tomato plants in here from growing outside. This was to improve the temperature for them to more ideal conditions. Tomatoes need to stay above a specific temperature to ripen. So they are harder to grow in very cool climates.
I also had the seedlings growing in here with Manchester Market turnips, swede, lettuce and beetroot. Since this is a warmer and sheltered area with the polytunnel, I removed the lid from the Gardman tray to prevent overheating.
Seed Growing Kits Can Give Plants a Head Start
There are many reasons why a special kit like this for starting off your seeds is a good idea. You can use these indoors in a sunny window and you can expect to get a better rate of germination than you would with seeds planted directly in the soil, in a raised bed or in outdoor containers.
Seeds grown this way are not hampered by bad weather and are not eaten by birds and other wildlife which is often an issue outdoors. You can give plants a healthy start by getting the seedlings to form strong roots before potting them on into larger containers or directly into prepared soil. Enjoy a better success rate with growing many different types of plants using this method.
Image Credits: The introductory image belongs to the author, Marie Williams Johnstone. All other images (unless watermarked with the author’s name) are product photos from Amazon.