TorontoJoe
Administrator
Commercial mixes use chemical wetting agents. If you have access you can use things like worm castings and even vermiculite to retain water. Yucca extract is popular but I have no idea the cost. Basically anything that retains water. I'm also told that if you pour very hot water over peat and let is sit over night the peat will absorb water.
Something like this is also an option
Something like this is also an option

ROOTS Terra-Sorb Fine
Super absorbent hydrogel holds up to 150 times its weight in water for planting and transplanting trees, shrubs and flowers. Fine grade particles for bare root dipping.
www.lebanonturf.com