The problem with growing for kids is that their taste buds are very sensitive. They will often eat only the best tasting fruit. Unfortunately, the best tasting fruit is often the hardest to grow. Commercially, plum is mainly grown in the deserts of the southwest because it is very susceptible to fungus. Apple is very susceptible to the curculio. Peach is a bit cold sensitive so NJ may be difficult. If you try to speed up growth and fruiting by watering and fertilizing it only makes fruit trees and vines even more susceptible to diseases and insects. Slow and steady is ideal. Another approach is to teach them about jams and jellies and instead grow the more disease resistant varieties. The most disease resistant are often the most nutritious, but not the best tasting. Jams and jellies helps to improve flavor. My favorites are: Grapes - Beta, Oberlin Noir, Marquette, Bluebell, Trollhaugen, Mars, America Apple - Liberty, Freedom Cherry - Evans / Bali, Surefire Apricot - Harglow, Jerseycot, Hunza Peach - Red Haven, Reliance Blackberry - Triple Crown, Doyle Of course St. Lawrence Nursery has some good grafted plums. And there are even some hardy exotics like honeyberry, raspberry, and current. Here is a link that might be useful: FRUIT

Asimina, here's few general pointers: Amending the soil used for backfill is not recommended. There is no point in making this tiny area of soil real good when in fact, what the new transplant must do to survive is extend its root system out beyond that area as quickly as possible. Additionally, drainage anomalies can occur causing the backfill soil to drain much slower, or in some cases, faster than the surrounding soil. That's not helpful to the tree. If you suspect your soil is deficient in organic matter, and it very often is, amending the entire area into which roots may eventually grow is a good idea. Here you're talking about essentially your whole yard. Well-made compost is ideal for this. Depth of planting is crucial. You want to plant such that the root flare, that swollen area where trunk meets roots, is at or just slightly above grade. Do not loosen soil under the tree's root system in the hole. Doing so may cause settling, and if it does, the tree will now be planted too deep. Mulching is the single most cost-effective treatment to ensure survival and rapid establishment. Don't get caught up in this or that mulch. Regular woodchips work well as does shredded bark, etc. Use what you can get cheaply. If the hole flares outward towards the top, the newly forming roots will have a "breakout zone" whereby they can more easily begin to colonize the wider area. Water mgt. is crucial and should be done such that the newly planted tree is getting the equivalent of roughly one inch of rain per week. In very hot, dry weather, this may not be enough. If weather is rainy, quite likely no watering will be needed. Don't fertilize at planting time. Roots develop fastest in a low-nitrogen environment. I expect more will be forthcoming. But this should get you started. +oM

An evergreen compatible with your USDA zone would look nice planted behind the tree so that the beautiful bark color is enhanced. Other than that, I am not sure what to plant under the tree. Maples grow shallow roots, and I would be afraid of causing too much competion for JM roots by planting shrubs. there are some nice annual flowers that look nice under JMs I have seen people around here mulch and grow pansies or other such long blooming annuals under JMs.

What is your question? What do you want to plant? There is no reason you can't plant under pine trees, you just have to see what plants you want there. Japanese maples, Rhododendrums, gardenias, hostas, really anything that prefers some shade will do well under pines. Pine tree roots grow down more than out.