Miracle-Gro Superphosphate

Miracle-Gro Superphosphate


in stock In stock

1.5 kg
Available stock: 12
Collect in Store

This item is available for collection.

Home Delivery

UK mainland delivery from £8.95

18% Superphosphate to encourage healthy root growth and better plant establishment. Ideal to use in spring or at the time of planting, and to toughen up soft growth in the autumn. Read the label and apply once or twice during the growing season. Use at 50-75g per sq metre and work into the surface of the soil. 

The name phosphorus comes from the ancient Greek meaning 'light carrier' and this gives us a clue to its function in living organisms.  Phosphorus is the 'energy element';  powering the critical life processes responsible for normal growth and function.

One important role of phosphorus is in the cell division process (meristematic activity) so any deficiencies will result in stunted growth of roots and shoots.  Early in the growing season the element is very important for root growth and hence good plant establishment. Attention to this pays dividends later in the plant's life in terms of optimising yields and produce quality.

Customer Reviews

By on
"Great customer service. "
Star Rating 5

The Basics

Ideal soil

Acidic soil, good organic content, pH 4.5-6.0. Inkarho range of rhododendrons will tolerate soils up to pH7.5

Sun or Shade

Light dappled shade is best for most varieties.


Refer to hardiness rating. Give young plants protection.

Site Selection

Avoid close to trees, roots, invasive weeds, walls, hot patios, dry banks and waterlogged soils. Do not use weed matting or stone mulch.

Plant spacing

Use the height shown in 10 years as a guide to the distance between each plant. Allow room for plant to fill out. If planting closer for instant impact, be prepared to move plants after a few years.


  • 3 litre pot, dig in 10-20 litres of ericaceous compost.
  • 7.5 litre pot, dig in 20-30 litres of ericaceous compost.
  • 70-80cm specimen, dig in 60 litres of ericaceous compost.
  • 100-120cm specimen, dig in 120 litres of ericaceous compost.

Planting depth

Plant high in the ground, with the top of the rootball visible.


Slow-release ericaceous feed recommended in March and straight after flowering.


Recommended every few years.


The key ingredient! Keep moist all season, especially the critical time at end of June for flower bud initiation. Tap water is better than no water. Heavy dose at least once per week in dry weather.


Ensure good drainage in winter, especially with yellow flowering varieties. Avoid waterlogged sites.


Rhododendrons and Camellias: Not normally required. Tidy wayward shoots after flowering.

Evergreen azaleas and Bloombux can be clipped into a low hedge.

Magnolias and Acers: Formative pruning when young to shape into a tree or bush.


Remove old flower-heads, particularly on young or weak plants.

For further advice see here

Size Guide

Size guide

Delivery & Returns

Our website calculates the delivery charge according to weight and delivery location throughout the UK. To see these charges, please enter your postcode at the checkout, and you will see the charge vary as you add more items to your wheelbarrow.

Please see here for delivery information

Please see here for cancellation and return information