Probably the most used propagation specific nutrient on the market, Formulex is a forgiving and simple to use one part nutrient for use with very young hydroponic plants.

Also works well as a balanced feed for early stages of growth in hydroponic systems, or as a full cycle feed for herbs and leafy greens in both hydro and soil.

From the manufacturer:

Formulex has a universal profile and was designed to grow all types of vegetative and floral crops to the highest standard. Professionals rely on Formulex for feeding seedlings, transplants and clones. Formulex remains popular with all types of growers, as it is cost-effective and straightforward use. The main benefits include:

Formulex has a buffered pH and usually requires no pH adjustment once in solution.
All elements are present and will remain available to plants through varying conditions of usage.
Will make up to 100 times its volume of working solution.
Designed for hydroponic applications where every nutrient element must be supplied in solution.
Suitable for hydroponic or soil cultivation and especially recommended for foliar feeding.
Formulex is meticulously formulated to express a pH of 6 when made up with tap water. Hydroponic growers no longer need to worry about pH.
Formulex is manufactured to exacting standards from laboratory grade materials. It is one of a range of products from Growth Technology that truly heralds a quiet revolution in horticulture.