Dig well, and deeply – at least 60 to 80 cm. deep. If planting in individual holes (such as for Standard or Climbing roses) dig at least 1 metre wide and 80 cm. deep: in beds, the same sort of depth, and whatever size of bed you want. Roses are “gregarious people” and like the company of other roses, so, where possible plant in beds, not individual holes.
Dig the bed initially to 40 cm. deep, and put this soil to one side, then loosen the soil below for another 20 to 40 cm.; leave stones up to about fist-sized in the bed – they help with drainage and aeration.
If your soil is heavy and retains water, either install drainage on a slope, OR make a raised bed to about 50 cm. above the surrounding soil level. For heavy soil, add coarse river sand, gravel, nut shells or peanut shells to loosen the soil. All the above must be mixed in well.
For very sandy soils you will need to add water-retaining material such as coir, peat moss or lots of compost to the bed, and one could also put a layer of rock wool or thick newspaper on to the sandy subsoil to help retain water.
The topsoil kept to one side should have the same materials added to it, and well mixed with lots of compost and old manure plus single superphosphate or bone-meal.
After all this preparation, drench with water to settle it all. (If water does not drain away after a couple of days, the area is NOT suitable for roses!)
Work out the spacing, – most bush roses need to be planted at least 80 cm. to 1 m. apart, so that each one can develop properly, and they are not too crowded, which will exacerbate the spread of pests and diseases.- and mark positions for each plant. Dig a hole the size of the bag the rose is in. Soak each bag to ensure the soil is very wet. Plant with the Bud Union just below ground level. Before removing the bag, check that your levels are correct, so you can add or remove soil in the hole to get the correct depth. Plant the rose, firming in well (walk round the plant) then form a basin round each plant.
Apply about 20 Litres of water to each plant. Re-firm the soil after a few days. Water every 3 days for about 3 weeks, longer if the weather is very hot and dry. About 2 to 4 weeks after planting you can level the basins and mulch.
All of this may sound like an awful lot of unnecessary effort and work, but remember, with care, your roses will be there, giving you lots of blooms and pleasure, for at least the next 12 to 15 years (or longer) and you can never go back and “re-prepare” and no amount of later top feeding will ever make up for poor preparation!
So, rather take the time and trouble now, to ensure good rose plants for many years to come.