Question
i would very gratefully if you could detail for me how to propagate blueberry plants.i bought 50 seedlings. the have almost no roots.what i can do to increase the probability of their survival

Answer
Good morning Antonio, and thank you for your question!
Before I can give you a proper answer, could you give me a few more details?

First, in what area do you live - blueberries thrive better in some areas than in others; What is your soil like? for instance, is it acidic or alkaline? Blueberries must have acidic soil with a pH around
4.5-5.0.  You'll know your region has acidic soil if Hydrangeas grow well and tend to be blue-flowered; or if other people in your area grow blueberries without having to amend their soil much.

Also Antonio, exactly what variety of blueberries do you have? It's quite unusual to buy them as seedlings. Blueberries are normally sold as either 2 or 3 year old plants, since it takes them about 4-5 years to begin regular fruiting.  I would love to know where you got them! They must have been much more affordable than the expensive older plants. If the place you got them has a website, or other contact information, I would really appreciate it you have time to pass that information on to me!

How large are the seedlings? You said they have almost no root system - can you tell me what the roots look like or send a photo? If you have wild blueberries, they grow more like groundcovers and don't have a strong root system, where the highbush blueberries (Examples of highbush blueberry names are: Meader, Bluecrop, Northblue, Northland, Northsky, Berkeley, Blueray, Jersey, Patriot, Rubel, Weymouth, Concord, Coville, Herbert and Stanley.)have very shallow, but slightly stronger roots. To get good fruit production, you should have at least 2 different varieties growing by each other; 3 is even better.  Do all of the blueberries you have, have the same name?

It would help to know where the seedlings are now. Are they planted outdoors, in a greenhouse, in plastic flats or small pots?

Wherever they are, you need to know the pH of the soil around the plant.  If it's over 5.5, you can lower it by adding 1 1/2 to 2 pounds of sulphur per 100 sqare feet for each full pH point above 5.5.
For example, if your pH is 6.5, add 3-4 pounds of sulphur (available at gardem centers) per 10 ft by 10 ft. area.  You won't have to adjust the soil again for another year.

Plant and water your seedlings (if they are dormant now, you can plant them out now. If they are awake and growing leaves, wait until after the last frost for your region) and put a 2 foot wide circle around each bush, of acidic material such as pine needles, oak leaves, partially rotted wood chips or shavings of oak, pine or hemlock. Always mulch blueberries: it holds in the moisture they need and you won't need to cultivate or weed around them. They all have very shallow roots and need regular watering and feeding with fish emulsion, composted manure, or the following recipe which I'd like you to try on your seedlings. It's designed to help them build strong roots and top growth, and it makes them very resistant to diseases.
Here's the recipe for THE ALL-TIME GREATEST PLANT FOOD!

1 Tbl. liquid or dry kelp/seaweed (save money by going to a health food store and buying powdered kelp. It's very inexpensive. Just mix it with water until it's the consistency of thin buttermilk.), 1 tsp. Blackstrap molasses, 1 Tbl.willow tea, 1 gallon of water. (The willow tea is made by taking a twig of willow - any kind - and cut it into 1 inch bits.  Soak it in boiling water for a couple of hours or at least until it cools completely. Strain out the twigs.) Put the fertilizer into a spray bottle and spray the plant's leaves, both top and undersides. You can then water in your plants with this mix, as well.  The kelp has high amounts of nutrients, natural plant growth hormones, trace minerals and has been found to make plants more pest and disease resistant. Willow contains natural plant growth stimulating hormones. The molasses contains iron, sulfur and simple sugars which nourish the plant.

I hope this has helped some; do get back to me with those details so I can give you a more precise answer.  I look forward to hearing from  you!
Best wishes,
Eirinn