How To Grow Agapanthus Plants

These tips will describe how to grow Agapanthus successfully and help keep your Agapanthus plants looking great.

Planting in the Garden - Agapanthus thrive in well-drained soil, in a sunny site that receives sun for most of the day. In heavy soils, mix in grit when planting to improve drainage, otherwise follow the instructions on the reverse of the label. Dwarf plants can be planted 30cm apart and larger forms 60cm.

Hardiness - Agapanthus have fleshy roots and leaves which can make them prone to frost damage. The hardiest of Agapanthus are deciduous, dying down in winter. They will survive most UK conditions once they are established.

Evergreen types are more tender and their leaves can be damaged by frosts. Therefore, a mulch of straw or fleece is advisable when young plants are establishing or extreme cold (below -5ºC) is forecast.

Established clumps of evergreen Agapanthus can withstand -10ºC to -15ºC if the ground is well drained, but the number of flowers maybe reduced the following summer. Planting in beds against house walls can reduce the likeliness of frost damage.

Growing in pots - Evergreen cultivars are especially suited to being grown in pots, allowing them to be brought into a conservatory or greenhouse for the winter. Use a loam based compost like John Innes No3 with slow release Miracle Grow granules added for long term feed. Liquid feed with Miracle Grow All Purpose Feed or Phostrogen during the growing season.  Overcrowded plants should be re-potted in spring.

Feeding - Agapanthus are quite hungry feeders.  For best results apply a top dressing of our Agapanthus Plant Food to the surface of the soil.  It is best applied first in March, then repeated in May and August. Alternatively, liquid feed plants in containers with Phostrogen liquid feed during the growing season or tomato feed which contains high levels of Potash. A sprinkle of Sulphate of potash can also encourage flower quantity and colour. Avoid giving plants too much Nitrogen or you will encourage lush leaves at the expense of flowers.

Pruning - Flower stems should be cut down after flowering, unless you wish to
leave them for winter structure in the garden, or spray them silver or gold once dried as Christmas decorations.

Dividing and encouraging flowering - Plants that don’t flower or are over-crowded may be divided in late summer after flowering or in early spring. Large plants maybe pulled apart using 2 forks after lifting from the ground or removing from the pot. Agapanthus doesn’t like to be re-potted into pots that are too spacious as this will encourage leaf growth rather than flower production. Ideal conditions are provided where root development is restricted but the plants are well watered and fed through the growing season. The belief that flower production is maximised when the roots are climbing out of the pot is not correct.

Why won't my Agapanthus flower? - It is a myth that Agapanthus must be grown with their roots heavily congested-they love water and are hungry feeders so with no soil in the pot it’s hard to give this to them. If your plant is flowering do nothing! If not-

  1. Give it maximum sun
  2. Feed it high potash fertiliser such as Fairweather’s Agapanthus feed
  3. If it is evergreen ensure that it does not get frosted in winter – buds are formed in the autumn
  4. Divide if it is over congested
  5. Buy a new one!


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