Hardening and Strengthening seedlings

Chillies and toms like a fairly dry compost when young, so don't over water, and when you do water, just put the pot in a tray of water for a couple of minutes to take up what it needs.
Personally I wouldn't use a home made compost for seedlings, as it may contain bacteria/beasties that the tiny plants can't cope with. With a shop bought compost, you know it's sterile.
Other than that, just be patient - I have 5cm tom seedlings too, it's not even May yet!

Hi chasingmytail. Well done for getting them that far. Now they need warmth and plenty of light, plus sufficient nutrients and water. So I have a few questions for you.

What's the source of light in the bathroom? Are they getting enough of it for healthy growth? Their stems grow too long and weak if they don't get enough.

How warm is the bathroom? And how steady is the temperature? Tomatoes grow best between about 12 and 25 C and their growth can be slowed or stopped if it goes much outside that range. Although some varieties are more cold or heat tolerant then others. The plants often get a purple tinge if temperatures go too low.

How did you make your compost? What are the ingredients? Growth can be slowed or stopped by too low or too high a level of nutrients, or an incorrect balance of them. That's another reason why it's generally better for beginners to use a bought, ready-made compost, so you can get to know what a healthy plant looks like and how fast it should grow before you start experimenting.

Water, well I think you can really only learn by observation what's the right amount for each type of plant. Some people swear by only watering from the bottom. I usually water from the top and don't find it causes problems, but maybe my climate is dryer than most people's here.

I forgot to say anything about the cucumbers and squashes. It might be overwatering. They like quite a lot of water, but don't like to be left standing in it. It could also be temperatures that are too low, or the wrong level of nutrients in your compost. What stage did you get them to and how did they look when they were dying? They can be quite tricky, especially cucumbers. But you've plenty of time for another go because many people haven't started sowing them yet, including me. I suggest using multipurpose compost so you can rule out that being the problem, and keep them good and warm.

Thanks My compost is excellent as grown loads in it over the two years. We use it on the farm. My bathroom is south facing and lots of light its well over 20 as underfloor heating too.

I prefer to use my own compost for the reason as I had much success prev, its here and saves money. Its not fine its quite bitty but had no issues.

I think the overwatering is correct and perhaps I should spray with light squeeze not pour.

If you've had so much success previously in growing these kinds of seedlings I'm wondering why you're asking us for advice.

And what do you mean by "my own compost" ? The word compost has two different meanings in English and I don't know which kind you're talking about.

One meaning is the stuff you make by decomposing organic matter in a composter or compost bin or compost heap.

The other meaning is a mixture of ingredients that's used to grow plants in modules, pots or other containers. It's often called potting compost or potting mix. Americans tend to call it potting soil. The original ones were based on sterilised soil with added ingredients to provide the correct pH and nutrient levels etc. Nowadays they are more commonly based on peat or other vegetable fibres. Multipurpose compost (MPC) is the most used type but there are more specialised types e.g. seed compost and ericaceous compost.

The first kind of compost on it's own is not usually suitable for growing seedlings or most plants. Its main use is to improve soil by adding more organic matter. It also has some nutrients, though the amounts could be very variable depending on what was composted.

Most people buy the second kind but there are various recipes for making your own, which can include a proportion of the first kind. If you've discovered a successful recipe we'd all like to know about it and what you've managed to grow in it.

I put my pepper plants in the GH from around 7cm and they've grown fine so far although they do seem to have stopped in height but are widening out. Cucumber plants in the GH from the first 2 leaves and are well on the way, growing nicely.
GH planters are watered from the bottom, only from the top when they were first planted to style them in.

However, farm, underfloor heating and making your own compost doesn't seem to sound like a total novice!

U-i have a mini propagator and some seed trays on a windsill

i have a small watering can , removed the end of it, then i just water around the edges of the seedlings in a pot, too much water can ive found cause them to tipple over. i then go back over the compost again with a bit more water as if the composts is too dry water wont soak into it

i then move the seedlings when big and strong enough to the outhouse window sill , its not great there but still warmer than outdoors and they protected

finally if a nice day i move the trays outside to get them used to outside temperatures

this year stuff has started off o,k, then had a cold snap , timing is key at all stages

I tend to over water - so I now use capillary matting which helps a lot -