Lizza, if I were you, I'd tell myself it was a learning experience, go to the library or bk store and get some bks on bonsai, and then try again with new plants from a nursery (cheaper, bigger, which allows room to learn pruning, etc., and more likely to survive than those little ones - your new ones can be little one day, but must start out large first). The pineapple might need to be kept inside as its tropical, but needs to be watered and treated specifically like a pineapple, and not to a schedule like a house plant (and spraying any of them doesn't work, just invites mildew). The other two have to live outdoors all of their lives, like any baby maples or junipers, and should also be treated like what they are... both (esp. the juniper) like to dry out to some extent before being watered again, for instance. Lots of trees look dry if they're overwatered, so unless you know for sure that they're not overwatered (and the juniper at least has been) it's hard to tell the diff. Being 'babies' doesn't mean you treat them like porcelain, they're trees and need all the advantages of growing up outside like any others, and that includes going through winters, etc. Mall plants are not good learning material though, and after reading up on bonsai, try nursery plants instead. And don't worry - we all lose lots of these things in the beginning. When you do water trees, do it from above, til all the soil's had some, but leave more time between waterings. And you need to learn about repotting into faster draining soil (the stuff yours came in was not to help the plants, but to weigh less (cheaper) for transporting them!

Looks very much like a soil issue. Something toxic...that could be attributed to many things... looks like fertilizer burn. Not saying that is it but what would be the outcome if an overdose of fertilizer is spread all over the soil, on top, and not tilled in or double-dug well in advance of planting... Lets back up a couple months...(because your raised bed soil looks very much just like your surrounding yard soil)...and the fact that this in not your first garden season... A month or so before planting, add your amendments of choice, double dig them in and rake and pull any sneaky weeds...this will evenly distribute additives and airates your soil....nice and fluffy...give it a good wet drink and rake smooth. Avoid stepping and compacting. I then cover my beds with a weed barrier that allows rain water in, not plastic. That just preps my beds for a good planting week...plants that like cooler weather go in often a month ahead of others like peppers, cukes, tomatoes... I mulch a week or two after everyone has settled in. I don't think it is the peat pots. You've got others in plastic and various suppliers. Bonnie, etc. I avoid them like others...but did purchase a bonnie this year...at least it has a plastic sleeve...and i pulled a bit of the peat away to inspect the roots before buying...just takes one inattentive employee assigned to watering to stress nursery starts by giving barely a sprinkle and not a soaking...so your plants could have been stressed before you even brought them home...(why many of us start our own plants and can only blame ourselves for failure and even then can have unexplained disasters but it does not cost money, just time and effort) A good soil analysis with some of your leaf matter included will solve any mysterious fungal issue...remove your plants...they look not so good by the dried up roots...may recover in a deep tray of pro mix? Not so sure...but i would double dig your bed...with a spade, one end to the other, flip your soil and water it soaking wet...while you wait for test results. Then add what is needed... So sorry, but their is still hope and plenty of time for a good growing season...

I think we have positively identified it from my "Name that Plant" thread. Users trini1 & Alisonoz have recommended Rain Lily - zephyranthes, it seems correct! With that in mind, anyone have experience with rain lilies dying back over late summer & should I tale any extra care steps? Also, is there a way to update the name of this thread (with Rain Lily title) so others can find it? Photo of Rain Lilies (for comparison) from the net:

The leaves on a tree that dies in the summer will often just turn brown and hang there. If the leaves are falling, the tree is still active metabolically. Leaf senescence is still driven by a plant's metabolic processes. Doesn't mean the tree won't die at some point...just that it's not dead yet.