Farmyard manure is one of the best things you can add to Irish garden soil, and roses in particular respond to it magnificently. That is not a complicated answer and it does not need to be qualified with many caveats. Roses are hungry plants, they thrive in rich, biologically active soil, and well-rotted farmyard manure delivers exactly that. It improves soil structure, it feeds the microbial life in the soil that makes nutrients available to plant roots, it helps retain moisture during dry spells and it opens up heavy clay ground to allow better drainage and air movement. There is very little that a bag of synthetic rose feed can do that a generous application of good farmyard manure around the base of your roses cannot do better and more sustainably. The question is not whether to use it but how to choose it correctly and what to watch for.

The single most important thing about farmyard manure is that it must be well rotted before it goes anywhere near your plants. Fresh manure, or manure that has only partially broken down, is too high in ammonia and will burn roots rather than feed them. It can also carry pathogens that have not yet been destroyed by the composting process. Well-rotted manure is a different material entirely. It should be two years old at a minimum. The test is straightforward: it should not smell. Fresh manure has an immediate and obvious smell. Well-rotted manure that has been sitting and breaking down for two years or more smells of very little, perhaps faintly earthy, nothing more than that. The texture should be crumbly and friable, like good dark compost, not slimy, not sticky, not wet. If you pick up a handful and it holds together in a clump rather than breaking apart, it is not ready. If it crumbles easily between your fingers and has a dark, rich colour, that is what you are looking for.

How you apply it depends on what you are trying to achieve. For established roses, a generous layer worked into the soil around the root zone in late winter or early spring, before growth gets going, is the standard approach and it is hard to beat. Work it into the top layer of soil rather than just leaving it sitting on the surface, which gives the roots more immediate access to what it is releasing. For new planting, mix it through the planting area thoroughly before the rose goes in, at a rate of roughly one part manure to four or five parts existing soil, and your rose will establish into ground that is already biologically active and nutrient-rich from day one. As a mulch applied around established plants in summer it also does a fine job of suppressing weeds and retaining moisture during the drier months, though if you are using it as a mulch keep it a few inches away from the main stem to avoid any risk of rot at the base.

The combination of farmyard manure and biochar is worth understanding because the two materials work in genuinely complementary ways. Farmyard manure releases nutrients and feeds soil biology as it continues to break down, but those nutrients are water-soluble and in a wet Irish climate they can leach out of the root zone relatively quickly, particularly in the open ground. Biochar, which is the active ingredient in Nutrichar, works differently. It is a highly porous, stable carbon material that acts as a reservoir in the soil, holding nutrients and moisture in a form that plant roots can access over a much longer period. The two together — farmyard manure providing the biological richness and nutrient input, biochar retaining it in the root zone rather than letting it wash away — produce a soil environment that is significantly more productive than either would be alone. If you are working on a rose bed that has been underperforming, or preparing ground for new planting, incorporating both is the most effective soil improvement approach available to a home gardener working without chemicals.

There is one warning that I would be doing people a disservice not to give clearly. When sourcing farmyard manure, particularly if you are getting it from a farm or a stable rather than a garden centre, inspect it carefully for weed contamination before it goes anywhere near your garden. Well-rotted manure that has been sitting in a heap for two years will very often have weeds growing through and around it. Nettles are not a serious concern — they are easy enough to remove and their presence in a manure heap is often a sign that the material is in good condition. What you must not bring into your garden is any sign of Japanese knotweed, ground elder or Scotch grass. These are plants whose root systems are extraordinarily persistent and whose introduction via contaminated manure into a garden bed is a problem that can take years to resolve. If you see anything unfamiliar growing in or around the manure heap, do not take a chance on it. The benefit of free or cheap farmyard manure is not worth the cost of introducing an invasive weed into your garden soil. The same principle of careful soil preparation applies wherever you are adding organic matter — what goes into your soil shapes everything that grows in it afterwards.

One final note on the vegan question, because it comes up and it is worth addressing directly. If you are growing edible crops and anyone in the household follows a vegan diet, farmyard manure is not appropriate for use on those beds. For edible growing in that situation, there are excellent plant-based alternatives including seaweed meal, composted green waste and mushroom compost that will do a comparable job of improving soil biology and fertility without the animal product question. For ornamental beds, roses, shrubs and trees, there is no such concern and farmyard manure remains one of the best organic soil improvers you can use. Pair it with a biochar-based soil conditioner to lock in what it delivers, and your roses will show you the difference within a single season.