Plant Care - FERNS

  • Most (but not all) ferns are shade lovers so in general avoid planting in windy conditions and in full sunlit areas (see chart for best plant location spots).
  • Greatest losses we find are due to inadequate watering (or planting in harsh windy and over sunny locations with consequent drying out - they are not cacti!!) In Summer and during any dry period water roots and trunk at least 3 times per week, other times twice per week in the absence of good rainfall, a good deep water is required rather than light sprinkle.
  • Fallacy - you drench ferns from the top and they will always grow! Not always as you can induce crown rot with too much water poured over the top, a light top watering is recommended.
  • Soil conditions - ferns are pretty hardy and generally quite shallow rooting but best soil type is free draining and compost enriched. Some ferns will handle clay soils ok though. Good idea is to put a mulch around the roots to keep soil cool and retain moisture - think of what the forest floor looks like!
  • Fertilising - once per year a light side dressing with a slow release fertiliser (e.g Osmocote 8-9 month release) is a good idea. DO NOT use fertilisers that will burn roots - e.g Nitrofoska Blue.
  • Planting depth - work on depth of pot or bag you buy the fern in.
  • Pests - generally ferns are quite pest resistant but some ground ferns e.g Hen and chicken fern (Asplenium bulbiferum) can attract aphids and some others (e,g Polystichum vestitum) can get thrip - if sighted spray (use at lowest of recommended rate) with insecticide. Snails like most aspleniums so snail bait now and then will help especially for ferns in Spring with new fronds.
  • The other pest that gets on tree ferns and lays eggs at the tips of the frond causing dying off of the tip is the Passion vine leaf hopper - spray in November to Jan the usual time for these to appear with garlic pyrethrum.
  • Diseases - some tree ferns (mamaku and squarrosa in particular) can get crown rot (growing tip gets mushy) if they sit with too much water in crown especially after long dry period.
  • Generally ferns don't suffer from fungicidial diseases too much and spraying is not necessary however it is a good idea to space your ferns out well to allow air circulation as this will assist with prevention of wilting.
  • If fronds on tree ferns brown off suddenly it can be due to wind burn on fronds that are not quite hardened off - put in a more wind protected area and maintain a good watering regime to encourage newer fronds as the affected ones may eventually not fully recover.
  • Yellowing of fern fronds - in ground ferns often due to over exposure to direct sun (need more shade to allow normal greening to operate) so you have them in the wrong place OR if the pot/bag looks very old and roots are coming through the bottom and fern is struggling probably root-bound with lack of nutriment, take out and trim back side roots and re-pot with new potting mix or plant out now!

Latest News

Re-locating a tree fern We sometimes get asked the question "we have a tree fern (not sure what variety) and we want to relocate it from its present position - can we do that and will it regrow?"
Notes on Tree Ferns To many people one tree fern looks just the same as any other and we are often asked for a "ponga" and the requester expresses surprise that there is more than one variety!!!