Two different jobs get lumped into one category here: feeding a plant, and helping its roots establish. Most planting benefits from both, so the real decision is which combination fits what you are planting and the soil it is going into.

Feeding, or root establishment?

A fertiliser supplies nutrients the plant uses for growth. Mycorrhizal fungi does something different: it forms a symbiotic network with the plant’s roots that helps it take up water and nutrients from the soil it is already in, particularly useful where that soil is naturally poor. Rootgrow Professional Mycorrhizal Fungi is applied once, at planting, sprinkled onto roots or used as a dip for bare-root stock, and one treatment lasts the plant’s lifetime. It is not suitable for ericaceous species such as rhododendrons and heathers. Fertiliser, by contrast, needs reapplying as the feed runs out. The two are not a straight either/or: a tree or shrub commonly gets mycorrhizal fungi at planting and a fertiliser alongside or afterwards to feed it while it establishes.

What are you planting, and into what soil?

For trees and shrubs going into the ground, Rootgrow Professional at planting time and Velscape Slow Release Tree & Shrub Fertiliser (4-19-10 + 8% MgO) afterwards cover both jobs: the fertiliser’s high phosphorus supports root development and the added magnesium strengthens the plant and increases hardiness, with one application feeding for around 5 to 6 months so beds need fewer repeat visits.

For turf, wildflowers or new seedlings, especially on soils that are naturally deficient, reclamation sites or otherwise hostile, infertile ground, Rootgrow Turf Mycorrhizal Fungi combines mycorrhizal fungi with zeolite, natural fertilisers and a moisture-retention additive in one product. It is also recommended as an addition to a hydroseeding mix, where it helps establishment on the same kind of difficult ground.

For general turf, borders and vegetables that just need a steady, balanced feed rather than a specific establishment boost, Velscape All Season (Growmore) Multi-Purpose Fertiliser (7-7-7) gives even nitrogen, phosphate and potash rather than pushing one nutrient over another, suited to lawns, parks and general turf cut to 10mm or above.

Which product for which job

Planting several trees or shrubs on the same job usually calls for both a mycorrhizal treatment at planting and a slow release feed to follow. For soil that is genuinely difficult, reclaimed ground, compacted subsoil, anything a spade fights against, mention it when you enquire, since that is where Rootgrow Turf or Rootgrow Professional earn their keep over a fertiliser on its own.

Frequently asked questions

Can I use mycorrhizal fungi and fertiliser together on the same planting job?

Yes, they do different jobs. Mycorrhizal fungi such as Rootgrow Professional helps roots establish and take up nutrients from the soil, while a fertiliser like Velscape Tree & Shrub supplies the nutrients themselves. Trees and shrubs commonly get both.

Why can't I use Rootgrow Professional on rhododendrons or heathers?

Ericaceous plants such as rhododendrons and heathers are not suitable hosts for Rootgrow Professional's mycorrhizal fungi. Check with the sales team for an alternative if you are planting ericaceous stock.

How often does a slow release tree and shrub fertiliser need reapplying?

Velscape Slow Release Tree & Shrub Fertiliser feeds for around 5 to 6 months per application, so a bed typically needs fewer repeat visits than a standard release feed.