Seedlings, like you have are genetically random in nature.
The apple you got the seed from most likely will not be the same apples that come from the tree.
Also, as a seedling, there will be no restriction in the size of the tree, so after 20 years the tree may be 25 feet tall and will become a massive inconvenience to prune and pick. Seedling trees may take up to a decade to produce fruit.

Do yourself a favor and order a tree from cumminsnursery.com, they come on rootstocks that dwarf the tree and provide resistance to some diseases, they also will produce fruit in 2-3 years. They have a wide variety, and for my backyard, they fit the bill well. Remember, with smaller trees, you can plant many more different varieties!

Here is a link that might be useful: Cummins Nursery

Anna, your son's seedlings could very well grow into full-sized apple trees and produce fruit in several years. Still, it's impossible to say just what the apples they give you will be like, as all of the rich genetic inheritance potential of the huge apple family is cached in those seeds that you guys planted.

If your son's apple seeds came from a grocery-store apple then they are almost certainly from a large orchard. It's common practice in those orchards to have a number of crab apples here and there to provide pollen.

The fruit from those trees will be true-to-type, but the seeds of the same fruit will produce crosses, no way around it. (Seeds are subject to all the rules of sexual reproduction; to get true-to-type fruit one must resort to cloning the desired variety via grafting.)

As a rule seedlings will grow into "standard" (big) trees, although there are exceptions.

But by all means go ahead with the tree if your son's interest holds. It should grow, bloom in a few years, and produce some kind of apples and it's a great opportunity to learn about it all.

Good luck,

M

I would say, if your son is really interested in this project, to plant no more than one of the seedlings. Then decide if you really want to grow a small orchard and take megamav's advice, if so.

A lot of people plant an apple tree without realizing how much work it is [spraying, etc] to get edible fruit, even from a good tree. And to pick it, if the tree grows to full size, as a seeding probably will, eventually. So you get yards full of wormy fallen apples rotting on the ground, which your teenage son probably won't want to pick up.

By all means plant the seedlings your son is growing. You are in San Francisco, and apples are really easy to grow in California, we are lucky in Northern California in that we don't have to spray much.

Seedlings usually produce good fruit for backyard orchardists. While your seedlings may not bear bland, perfect looking commercial grade apples, you most likely will get much more interesting fruit than what you can buy at the store. However, keep in mind what Mark said above, if your apples came from Washington State, chances are they may be pollinated by crab apples. If they were grown locally, your chances are much better as it's not common practice to use crab apples as pollinators in California.

Most heirlooms are chance seedlings anyway, including even some contemporary commercial apples such as golden delicious and mcintosh. So have fun! If by some remote chance one of the trees doesn't produce good fruit, you can always have someone graft it over for you to another variety you like. But try planting all the seedlings you have, because it will greatly increase the chance that you will really find a new gem of an apple.

I've heard that about 1 in 1,000 apple seeds will produce a fruit of equal quality to the parent, 1 in 10,000 will be better than it's parent.

Johnny Appleseed was planting cider apples, not dessert apples ;o)

+1 to what peachymomo said. In other words, there's about a 99.9% chance that the fruit will be less than mediocre. But it will probably make good juice, and if you're lucky, good pie and sauce, if you don't feel like eating it fresh off the tree. And it surely is fun to grow your own from seed, and I think part of the fun is not knowing what to expect ~10 years from now when it starts fruiting.

which he planted in small pots with soil

===>> what they all said..

my concern is about growing trees .. in pots ...

soil is mother earth.. and is not real predictable in pots ...

and plain old regular potting MEDIA.. usually has too much peat and retains too much moisture for trees ...

you dont mention.. or i missed.. its size ..

planting tiny trees out in the lawn.. can be problematic ... so it might be to your advantage to keep it potted for this year.. to get some size..

but if you do.. you will have to invest in some proper potting MEDIA ...

Al's gritty mix is mentioned hundreds of time on GW.. use the search ...

and an alternative.. is a prepared bag of cactus mix ... presuming you dont need bulk ...

it has the extremely high drainage.. most trees prefer ...

and never leave a pot.. in sun.. you will cook the roots ... the prefect placement would be tree in sun.. pot in shade ...

after that.. its all about PROPER WATERING ... and it isnt anything like you would water a perennial/annual ...

ken

Shoot.. Why not plant them in the ground... Let them grow.. then if you don't like them - dig them up or cut them down...

Sometimes, they are great, sometimes not so much.. and then they go.

I have done this plenty of times...

I think the odds for decent fruit are much better than 1 in 10000.
For years before we had property we would cruise the roads for feral apples. Most for cider(sweet and hard) but cooking and fresh eating too.

I would say half were useful in cider, a quarter were passable fresh and maybe 2-5% were great apples we would look forward too each fall.

Some bird pooed an apple seed on our property two and a half decades ago. It grew to be a lovely, large tree who is an extremely heavy producer of a good quality fruit. It has never been pruned, sprayed or trained. It just gives us apples, and enough left over to feed deer and most years so much we have to push the drops over the hill with a front end loader. Passable for eating, but great for pies and sauce. It was astounding beautiful this year in bloom. Just a random seed.

'I think the odds for decent fruit are much better than 1 in 10000.'

I never said they weren't, I said that the odds of a seed producing an apple superior to the parent (assuming the parent is a dessert apple) are 1 in 10,000. To get a fruit of equal quality to the parent the odds go up to 1 in 1,000, but if you're just looking for a decent apple I'm sure they are higher. There is also a chance that what grows won't even resemble a tree very much, apples have the largest plant genome sequenced so far by scientists so there is a greater range in genetic diversity among apple seedlings than there is for most (if not all) other types of fruit trees.

Here is a link that might be useful: Apple Genome Cracked