sounds like the water and soil amendments may have been detrimental.

Merv Turner, the hybridizer responsible for the Bush Gem series wrote an article in the August 1986 publication of the Australian publication Gardenscene. He set down the following 5 rules for the cultivation of Kangaroo Paws.

1. Plant in a sunny and open position in the garden. If in a frosty area, plant under eaves on the south side of the house or under a high tree canopy.
2. Provide these plants with excellent drainage.
3. In summer dry climates provide these plants with regular water (providing the drainage is good) to keep plants evergreen.
4. Fertilize, but not heavily, and keep Phosphorus on the low side.
5. Annual clean up. After the flowering period remove the old leaves down to as low as possible. Fans only flower once and need to be cleaned out at the end of a season. Care should be exercised that the new emerging fans are not damaged.

Planting
Although plants can be established at any time of the year, it is best to plant during the cooler months: either late in the fall or in early spring. If one is planting in a location where medium frosts are expected, protect plants with mulch or wait until spring to plant. A sunny position in the garden is generally best although many of the species and hybrids will grow and bloom in an open light shade. If the location suffers from hard frost, plant in a sunny spot under eaves or under the protection of a tree canopy. Kangaroo Paws do best in, and in fact some will tolerate only well drained soils. A. flavidus, the most common species in cultivation in the US, and parent to most of the common hybrids, tolerates heavier soils than the others, but still responds to more favorable conditions. It is reported that A. manglesii and rufus also will take heavier soils and that all three tolerate seaside conditions.

Irrigation
Summer irrigation seems to shorten the life span of Kangaroo Paws, for all species except A. flavidus, yet many of the hybrids will look best if given ample water until the flowering period is over in late summer. Many of the species come from areas of prolonged summer drought and will tolerate similar conditions in cultivation; these species tend to be summer dormant and are easily rotted if given water once in dormancy. For the best production of flowers the cut flower industry in Australia has been advised by their Agricultural Department to drip irrigate on sandy soils daily during the summer. A fertilizer can be supplied through irrigation water. In California, cut flower growers keep stands evenly moist until flowering has finished in fall. In the landscape Kangaroo Paws can be irrigated in a different manner. A. flavidus, A. humilis, A. rufus, A. manglesii and A. pulcherrimus are all species that grow well in dry summer climates. Many of the better hybrids have one or both of these plants as parents and likewise can be treated in a similar manner. These plants can be grown with other Mediterranean climate plants in a dry, or infrequently irrigated garden. It is still advisable to use drip irrigation when irrigation is performed, as this lessens susceptibility to disease.