Not. One. Seed. Give up?

So sorry - I know how it gets us down, when nothing comes up...

I hwve basically given up sowing many things outside. I sow indoors, keeping the seeds near a radiator for warmth. To save soil, I sow many seeds in small lidded pots (herb cheese, hummus, etc) , and prick them out into modules as soon as they start to emerge. If nothing comes up, then the compost goes into outdoor pots, etc, so is not wasted.

For us the main problem is lack of rain. Like @Loofah we have had many seeds and plants fail because of lack of water. If you still have some seeds left, maybe try this? Do the likes of Lidl/Aldi sell seeds in the UK? Here the packets of seeds are as little as 0,49€, so less than 50p. I’m learning to use as many of these as possible, so as to have fresh seed each year...

 

I'm no expert by any means and my greenhouse isn't heated so I have had to cover most of mine in trays with lids. I've had some its worked with and some unsuccessful. It must be so frustrating to have all the seeds and compost ready to go.

 

We're only halfway through April FC, I'd give seeds another go if you already have them. I had a cold greenhouse in my last garden so cobbled together some garden canes and bubble wrap creating a kind of cloche to put over them, it covered a couple of dozen trays.

 

Everything is germinated in propagators indoors and grown on under lights. Plants needing natural light go out in polytunnel and are brought indoors if going to be too cold overnight and kept in stacking plastic crates stacked up to almost 2m high (also useful fot stacking in a fleece wrapped stack left where they are),

Only a few more days now before lots can go out leaving only toms and tender flowers to come in overnight.

Tip: Don't encourage puppies play with old flower pots as it can cause problems.

 

Too early to give up lots of time left, still got things to sow, my Tom's are still seedlings and the few I bought are actually too big and becoming a problem.
Admittedly a bit late for a few things but in your situation I'd probably buy a few plants.
And then there is always the big seeds that work even when direct sown.

 

Peas and beans I chit inside on damp paper towels in take away containers with lids on, check every couple of days and then when they start to germinate, root shows, I put them in a seed tray of compost in the greenhouse, water well and leave to reach an inch or two tall then plant out and put canes/netting up. Only way to stop the pigeons getting the lot. Last weekend I sowed sunflower and sweetcorn into root trainers in the cold greenhouse, this weekend french and runner beans will be sown in the same way. Need to keep an eye on watering as greenhouse gets quite warm in the day. A lot of seeds actually germinate better with a day/night temperature fluctuation.
You are not too late to sow leek and brassica seeds either in a seed bed or in pots/modules in the greenhouse once germinated harden off and plant out when large enough.
Pumpkins, squashes and courgettes can be sown outdoors mid May onwards so now in the greenhouse would give you good plants to go out end of May. I've had tomato seed germinate May/June time in old compost so don't give up on the ones you have sown, or you can sow some more. Yes you may get a later crop and a lot of green tomato chutney.
As you say lettuce, carrot, beetroot you can direct sow outside. Parsnip seed needs warm soil to germinate and I have sown into May and got parsnips that were carrot size.

 

Do you have a pasting table, or something similar?
I have one, that is permanently up, and it’s where I grow my plants on. It is next to a radiator, and under a velux window. The plants are not so vulnerable to puppies, as it’s not a case of putting paws up on a windowsill to look outside.

The pasting table (facing north west)
(I will soon be moving the citrus pip, avocado stone and date stone plants elsewhere, to give me space for another tray)

another window “set-up”, facing south east

(As we plant to move on fairly soon, we are reluctant to do too much, structurally, to the house, hence the Heath Robinson shelf)

“And that, your Honour, is my indoor growing space”...

 

Do the same as Nigel has said about peas and beans with sweet corn too. That’s what I have done in the past. I have also tried it with carrots and parsnips this year after watching YouTube video of someone doing it and growing in flower buckets. Which is what I am trying this year. Its really not too late to grow from seed and it looks like the overnight temps are picking up from today, so things should start catching up.
Rusty