Fruit trees from seed

It's probably true. Most fruit trees you buy are grafted onto a rootstock of some kind. Rootstocks are chosen for characteristics such as disease resistance; size management; vigour etc

People on here have grown lemons from seed, but I can't recall if any managed to fruit (you could look via the search button).

" most lemons ...[produce[ several seedlings from a single seed. Discard the weakest grower, which is the result of cross pollination and the rest will be carbon copies of the parent plant. However, you may have to wait anything up to 10 years to see them fruit. Grafting them onto Poncirus stocks will bring fruiting forward as well as increase hardiness slightly. When you think about it, the outlay of £20 or so for a fruiting plant is not a lot in view of the time saved." Growing Citrus trees - Gardening in the UK Forum - GardenWeb

That's probably right. I grew a lemon from a pip. It made a very big plant but never flowered or fruited and after about 5 years of putting it out in the summer and bringing it inside in the winter, I forgot it and the frost got it!

Hey, I've been looking into growing various fruits myself, mostly tropical. Most fruit trees and bushes take many years before they come to fruit. When cultivated they generally take cuttings from a fruiting tree and graft it onto a vigorous root stock but this won't make a non-fruiting plant fruit. For most fruits trees and I think all the ones you've mentioned, to grow for fruit is only really worthwhile with a nursery grown plant or a cutting of a known fruiting tree.

Growing fruit can actually be a relatively complicated business. Take for example figs, very very few fig trees grown from seed are capable of growing edible fruit and only a small selection of these produce worthwhile crops. Then there's the fact that you need both a male and a female tree and a Fig Wasp within range to pollinate them...

There are some things that are worth trying as I'd assume you're willing to overwinter. You can grow a pineapple from the crown of a fruit in about 2 years, OK so maybe it's only worth it for the novelty value. Papaya fruits in about 8 months in it's natural environment, but again you need a male and a female (or a hermaphrodite if you're lucky) and you'd also need to have it in a greenhouse or similar. Physalis (Cape Gooseberry) while not a tree is apparently rampant and fruits like crazy, grow like a tomato plant. My friend tells me he grew a 12' Physalis in one season.

I bought 4 Goji berry cuttings from eBay for £10 which were taken from a bush that was already at fruiting age. They should have fruited this year but unfortunately they're dead now. I wouldn't have bothered with seeds as it takes at least 4 years for the first crop and up to 8 years for them to get into full swing.

A seedling has to go through a juvenile stage whereas a cutting almost skips that and can go to flower much quicker.

There is also a very good chance that they won't be true to type.