[BryterLayter]

My brother is going to get Harry to grow some potatoes in one of those sacks where you keep topping them up. I suggested a salad variety e.g. Charlotte as its available from most local garden centres. I thought about suggesting a pumpkin but they do grow rather rampant.......Oh well, he will have to dig up some more of the lawn 

[barley]

how about a giant sunflower plant

kids love to watch them grow and like to be measured against it to see if it grows taller than them

they can feed the seeds to the birds after 

[jaydig]

My grandchildren loved eating peas fresh from the pods, small, sweet carrots, radish are very quick to germinate and come in a variety of bright colours. Dwarf beans could be started in a clear plastic pot, between the pot and damp kitchen roll so that he can see the shoots starting, before planting in the ground.All children love sunflowers, and when my grandchildren were small they planted some tall ones alongside the path in my garden. When I knew they were coming to visit, I removed some seeds from the central part of the flower and created a different 'face' in each one. They were absolutely fascinated.

[fisher]

Some ideas here for sensory garden with children - so all 'safe' plants- handy for any little and not so little ones!

http://apps.rhs.org.uk/Schoolgardening/uploads/documents/Plants_for_a_sensory_garden_270.pdf

Have fun!
Fisher

[Snoop]

Hanging basket at appropriate height with cherry toms suitable for growing in a basket. Maybe a thorn-free courgette. They grow fast, have dramatic flowers, and there's something to pick nearly every day for weeks on end.

[upthetump]

I ordered the centiflor toms from Real Seed Catalogue, appros  100 toms per truss. an amazing looking plant would be very visual for him

[JimB]

.

Kids attention span is short, so quick growing veggies and annual flowers to keep them occupied.

Even though you may not like them radishes are extremely quick to germinate and grow, and lettuce leaves also, with these they will have a sense of achievement very quickly!

Cheers!

[gypsy]

Sweet peas so he will be able to pick a bunch of flowers everyday for the ladies in his life. I imagine he will be so proud to show them what he has grown

[digalotty]

i find swiss chard easy to grow and it keeps coming so a good yield for a small plant also rocket is good for the same reasons, i wouldnt be without my strawberry bed and i will always grow potatoes just to see his face when you harvest them just get a pack of 5 from the pound shop, beetroot is also a good easy product
take a look at square foot gardening
 

[Snoop]

If you have space, sweetcorn is another goody. Grows really tall, has unusual flowers and then there is the surprise of peeling back the husk to see the kernels. And kids love the taste and experience of eating it. The only problem is you need a fair bit of ground, as you'd need a few plants to ensure pollination.

[fluffstermum]

We're in the process of making our 5-year-old a little raised bed on our allotment. It will be a 1.2m square.
I've asked him what he'd like to grow in his patch and initially he said carrots and strawberries (the things he most likes to eat).
Since then he has changed his answer to "one of everything" haha!

So we'll transplant some of our established strawberry plants into his patch, help him sow some carrots, and then probably just give him a plant of everything we sow on the main plot.
If he shoves it all upside down or squished up together in a corner it's no big deal, but I'm sure he'll have fun learning 

One thing we've done in the past, which your nephew might like too, is to buy some cheap wooden spoons and decorate them as labels for the things he is growing. Paint it in acrylics or similar, cover in clear varnish, easy peasy. It's a lot of fun spotting the various markers around the plot with little pictures of carrots, potatoes, sweetcorn etc on 

Sunflowers are also a massive hit. The bigger the better!

[Ema]

Peas and beans will be easy to sow and guaranteed to gain a rewarding and quick crop