Washington Navel orange To successfully plant a Dwarf Washington Navel Orange tree into the ground in Perth, WA, you need to follow a heavily enriched soil process. Because it is a dwarf variety, it will grow into a compact, manageable tree (around 1.5 to 2 metres tall), making it perfect for smaller garden spaces, but its shallow citrus root system still needs immediate protection from the nutrient-poor, drying nature of Bassendean dune sand.
The exact product you need to buy (you can buy from Bunnings Warehouse) to amend your soil is the Scotts Osmocote Citrus & Fruit Premium Potting Mix.
Exact Step-by-Step Planting Instructions
Because you are working with a dwarf tree, creating an open, rich, nutrient-dense "basin" in your sandy soil is the secret to getting sweet, juicy oranges early on.
1. Select a Position that will get as much Full-Sun as possible: Protect the tree from strong, salty, or drying winds, if possible, as high winds can strip the flowers and young fruit off the branches.
2. Dig a Wide, Shallow Basin: Dig a hole that is twice as wide as the nursery pot, but the same depth as the pot.
3. The 50/50 Native & Premium Blend: Mix 50% of your excavated native sand with 50% of the Scotts Osmocote Citrus & Fruit Mix right next to the hole. To give the sand extra structural "body" and water retention, aggressively blend a few big shovelfuls of composted cow manure or organic compost into this mix.
4. Set the Depth and Backfill: Place the tree in the hole. The top of the root ball must sit level with, or slightly higher (2 cm) than, the surrounding natural ground level. Never bury the trunk or the graft union, as this introduces collar rot and will eventually kill the tree. Pack your 50/50 soil blend firmly around the roots to eliminate air pockets.
5. Water In with Seaweed Solution: Immediately water the tree deeply. Drenching it with a seaweed tonic like Eco-Organic Garden Eco-Seaweed from Bunnings will significantly minimize transplant shock and encourage rapid root exploration. You can simply, soak the roots in WATER asap for an hour before planting and forgo Seaweed Solution.
6. Mulch Heavily: Apply a 5 to 7 cm layer of lupin mulch or coarse woodchips across the entire planting footprint to keep the soil cool and moist. Always keep the mulch a clear 5 cm away from the bare bark of the trunk.