How do I decide which plants or trees would prefer bark or something like Mulch & Grow? For example, a lemon tree or roses in the garden and tomato or cucumber plants in pots.
Possibly the most important issue here is that you mulch, rather than which particular mulch. Applying mulch around growing plants helps retain soil moisture, repress some weed growth, and as the mulch breaks down it improves the soils organic content.
Whatever product is easily available, be it; Daltons Mulch & Grow, Daltons New Zealand Pine Bark Nuggets, Daltons Compost or pea straw, these will all be of considerable benefit in your garden.
What is important is the depth of mulch that is applied and how frequently it is reapplied during the growing season. The recommended depth of mulch to apply is 50 -60mm. Too greater depth and water will struggle to percolate through, while insufficient depth and weeds will rapidly immerge.
The depth of mulch can be greater around existing mature trees and shrubs as opposed to around vegetables, where the depth should be less.