Lots of people pre-order plants. In fact, some plants are hard to get without ordering way in advance. From exerience, I can tell you that if you plan to do any hardscape engineering, it is best to do that before you plant. Kids in college are very expensive. My sympathies.

Join the seed exchange forum and get your seeds there. Then join the wintersowing forum and learn how to grow'em yourself. This will save you a TON of money and get you started. Then you can buy items as they come available, either by your "early bird purchases" or through clearance sales etc. Find local native nurseries, the prices are often a shock at first because they are so low (usually 2-3 dollars a plant/tree) but most times the trees/shrubs are only 1-3 feet tall and plants are seedlings but they are a cheap way to get things moving faster. Collect seeds on your own once you learn which seeds are native and then keep a record of where you collected them for future reference and then just broadcast them over your slope. Once they have matured you can move them about to better locations. Butterfly weed doesn't bloom if it doesn't have enough sun, so do your planting when foliage from above is at it's peak and you can find sunny spots to place the butterfly weed (ie. along your path and down near the open bottom of the slope near the tracks). Also, butterfly weed is slow to peak out from the ground in spring so don't give up on it. You have the benefit of the Gulf Stream so you will get an earlier sprout but here in southern Ontario where we are much colder, it is one of the very last plants (along with bleeding heart) to poke it's nose out of the ground. Start with purchased Butterfly weed as it will most likely bloom the first season (Walmart...very inexpensive and you can buy whole flats if you want) and plant them far apart from one and other. Then collect seeds in the late fall (October) and either save to germinate in the spring in flats or sow them right into the ground between your spaced apart mature plants keeping in mind they will need sun to bloom and give you their wonderful rich colours that attract monarchs during their migration.

I mentioned winter sowing a bit earlier. Some people have had magnificent success with it, so maybe it's something you will want to try as it will yield the large numbers you need for that big slope of yours. Here's the link if you haven't seen it already:

http://forums2.gardenweb.com/forums/wtrsow/

Have fun with it most of all. I've done a very similar project starting from nothing but a "mess" and now into my 3rd year we are seeing GREAT results from the methods I have suggested:

• seed sowing - just tossing/broadcasting near and far

• winter sowing and planting out

• native garden centers with cheap plants

• native plant sales at hort. societies, universities etc...

• purchasing more mature plants when they are inexpensive, early in the year or late on clearance

Good Luck and have fun with it! It will be prettier each year and if you don't believe me, take a photo(s) from the same location each spring, summer and fall and you will see the progress quite nicely. I have even made an animated 'gif' of our 3 year progress and the change is quite amazing in just a short amount of...

I just thought of something else and will post it here instead of going back to your other thread. You had stated you have Ailanthus there? I wouldn't do anything until how ever many of those trees are gone. And if, by chance, you have a female, remember she tosses out something like 350,000 seeds annually. They will continue to germinate for years and years and years......

Terryr is right that ailanthus will come back but I would still be inclined to do your project. I pull up ailanthus saplings every summer and manage to keep them under control.

I would second what knotty celtic said. With winter sowing, you could cover a huge area for very little money and do it quite quickly. I did a native slope last year with mostly winter sown plants plus a few purchased and a few more divisions from friends. Watch for native or any type of plant trade in the spring. Often, at the end of the day, people are just giving away truckloads of plants so they don't have to carry them home. Also, talks to friends, colleagues, church members about who likes to garden. You will run across some one with a big garden who can donate some spring divisions. I wish you were close to me. I could send you a bunch of stuff. Let me know how things are going in the spring and maybe we could check out what postage/shipping costs, and I couod send you stuff. E-mail me and I'll tell you a bit more about what I might have. I could certainly send you seeds if you want to get started on wintersowing for yourself.
Martha

Martha.. hope you are still out there.
Plant trade? never heard of one here on Long Island in NY. How does it work?
Cherry

Plant trades are put on usually in the spring. People who are looking for new plants, or who have extra plants from dividing their older perennials, come together to trade plants. I've only been to one trade, but for every plant a person brought, they got to take a different plant home. I understand some of the plant trades get very specific about who gets to pick their plants first and which plants are considered the most "tradeworthy" or something. Some also take turns, so everyone gets to pick one plant before the first person gets to go again. Somewhere here on Gardenweb people post when and where they are holding such trades, but I'm not remembering exactly where.
Martha