This article was originally published on the web at fuchsiaclark. pwp. blueyonder. co. uk, however that website is defunct at December 2016. The copyright remains with the original author(s).

Fuchsia Compost

Compost - composition and nutrition.

Potting composts available today vary tremendously both in structure and composition. They will all sustain plant growth for a limited period only. This may be fine for some plants but for fuchsia, especially show plants, it needs to be fortified and restructured.

Several decades ago, with the advent of research at the John Innes Institute, a soil based compost was formulated specifically for pot and container grown plants. This formula was eventually accepted as the maxim by most gardeners and nurserymen. It was a loam based compost made up of 7 parts loam, 3 parts peat and 2 parts grit to which base fertilisers are added. The amount depending on the size and type of plant to be potted. For fuchsias, lime needs to be added to correct the acidity of the added fertilisers. This compost was and still is recognised as John Innes Potting compost No's 1 2 or 3, depending on amount of added nutrients. No.1 is used for seed and cuttings. No.2 is used for established plants up to 15 cm pots and No. 3 is used for large pots, containers and baskets. An excellent product if you can find a good supply. It has several limitations.

  1. Weight, heavy to carry and transport.

  2. Short shelf life due to the added organic materials and moisture.

  3. Availability.

If you wish to use this type of compost, it is far easier to make your own provided you have a good supply of fertile loam. To the John Innes formula described above add the requisite amount of base fertilisers. These are as described below for soil-less and multipurpose composts. In use, the virtues of a soil based compost are its weight, plants grown outside are not easily blown over, its density, roots can not easily reach the inside of the pot as they strive to reach the drip line and the steady supply of nutrients governed by the progressive rise and fall of the compost temperature. The combined result is a healthy well balanced plant. An added virtue is its water retention qualities on hot sunny days.

The limitations of soil based composts have led to the advent of multipurpose peat and other soil-less composts. These are many and varied from coir to composted plant and other materials. They all have their merits and drawbacks which can only be determined by use. Try them. In addition, inert materials such as perlite and vermiculite can be used, using a technique called hydroponics. A novel and interesting way of growing plants in a solution of water containing all the necessary nutrients. If you use one of the multipurpose peat or soil-less composts, then you will be well aware of its limitations. On the plus side it is relatively cheap, easily obtainable, light weight, clean to handle, extremely versatile and available in many compositions. On the downside, the nutrients are mostly soluble in water and will only sustain plants for a limited period depending of course on the time of year. In summer they tend to dry out rather quickly, shrink, making re-wetting most difficult. When drying out, plants grown outside tend to get blown over very easily and damaged. Another problem are the roots, with no obstructions to deflect their path they go straight to the inside edge of the pot where they continue to encircle the pot in an effort to reach the drip line leaving the centre of the compost relatively untouched for some time. The drip line of course is the outer edge of the leaves or canopy. In a natural environment rain is shed from one leaf to another until it falls to the ground. This is the drip line where the roots expect to find food and moisture Once depleted the nutrients in soil-less composts need to be replaced by supplementary feeding using a liquid fertiliser to sustain balanced growth and development. Supplementary feeding is mostly a 'hit and miss' affair which invariably does more harm than good unless you are an expert. Many plants are lost or malformed through the misuse of mineral fertilisers which by their very nature are extremely acidic. Concentrations burn roots and turn the compost sour. In solution, the plant has no option but to absorb the diluted fertilisers. If this occurs you will notice a white residue appear along the outer edge of the leaves. This occurs during transpiration and the white substance is unwanted fertiliser. In loose terms it is being sick. It is more prudent to add additional organic and slow release mineral fertilisers to the compost and give the plant the discretion to choose what it requires. Another type of fertiliser that can be considered is osmocote, a liquid fertiliser contained in a degradable shells of varying thickness. I have tried these with limited success. Mineral fertilisers in solution leave the plant no choice but to absorb them and if they are administered at the wrong time can prove disastrous. The plant is far more adept at deciding when it needs feeding. The feeding habit of plants is determined and controlled by two factors. Temperature of the compost and the intensity of available light. The addition of organic and mineral fertilisers to the compost will sustain healthy balanced growth through to flowering without wondering whether to feed or not. The only time supplementary feeding should ever be considered is when the plants are in their final pots or containers and becoming root bound.

The points raised regarding the short falls of both types of composts had to be addressed. Multipurpose and soil-less composts need to be restructured for specialist use. Weight, additional fertilisers, a means of root deflection and means of aeration need to be added. This final point, aeration, is something overlooked by almost all growers both amateur and professional. What is not appreciated is, when using a soil-less compost, the roots developing inside the pot or container grow and expand compacting the compost. As this compaction increases with the plants development, oxygen, essential to the roots and micro organisms is gradually depleted. The result is a compacted compost with little or no drainage and almost devoid of oxygen. The compost turns sour and the microscopic feeding roots succumb to a water borne fungi. When the plant shows signs of distress two assumptions are usually drawn. The plant needs feeding, or it has been over watered. The assumption is right but the remedy nearly always wrong. Watering and supplementary feeding will accelerate the plants demise. Before attempting a cure knock the plant out of it's pot and check the root system. This will tell the whole story. If they are white and healthy, all is fine. If they have turned brown with obvious signs of decay you have found the problem. The cause will be compaction leading to over watering or poisoning due to over feeding or a combination of both. Unless the real cause is diagnosed and addressed the situation will recur. It is both time wasting and expensive, more especially if you purchased the plant to add to your collection. To virtually eliminate these problems try using the formula described below. It was developed over a period of five years to eliminate and overcome most of the problems outlined above. A point of interest. There has never, nor will there ever be, a compost that will turn a poorly grown neglected plant into a show specimen or an inexperienced novice into an expert. In addition to having a good compost you will need to care for and understand your plants to be successful. Plants, like you and I, are composed of living tissue and need to be treated with respect. Don't abuse them and you will be amply rewarded.


I have used the following compost composition for the past thirty-five years, not only for fuchsias, but for my collection of over thirty other different species. They all grow and thrive, some spectacular results. Take a look at my show plants, baskets and garden containers. Whilst exhibiting, I never divulged the compost composition or nutrient formula and was rarely beaten on the show bench. Using the same composition and formula I was able to predict the performance of my plants from year to year. The only unknown element was the weather. If you wish to test my formula I would stress the importance of reading it carefully and pay particular attention to notes of caution.

Firstly, decide which type of compost you are going to use. It matters not which type be it soil-less, multipurpose peat based or a soil based compost made to the John Innes formula of :- 7 parts fertile loam, 3 parts peat and 2 parts sharp sand or grit. I have on occasion used a combination of soil and soil-less to good effect. Compost has two major functions. Firstly, somewhere for the plant to establish itself with its root system and secondly the retention of food and moisture.

The measurements for compost is based on 40 litres volume.

To each measured bushel of soil-less or multipurpose peat compost add two five inch pots of coarse grit. This adds both weight and root deflection. Two five inch pots of perlite or vermiculite. This resists compaction, improves aeration and drainage . It also assists wetting when the compost has dried out. NB: If the compost has dried out always water with warm water. It has better penetration qualities than cold water and helps the plant recover more quickly. A wetting agent is now available and can be incorporated if required. Lack of aeration and compost compaction is the main cause of plant failure. If using the John Innes compost only add the perlite. Once the compost has been prepared it needs to be fortified with base nutrients, the amount of which will depend on its use.

Pay particular attention to the following paragraphs and heed any words of caution.

The base fertilisers to be purchased and added to your compost are as follows:-

Hoof and horn meal. Super phosphate of lime. Sulphate of potash. Steamed bone flour or fine ground bone meal. Magnesium Sulphate ( Epsom salts). Manganese Sulphate. You may need to contact a specialist re-seller if your local nursery does not stock these items. Nowadays, they are nearly always nicely packaged in one or two kilo containers. Having purchased these fertilisers, the first thing to do is open each container and carefully pass all the contents through a flour sieve, then store each in separate watertight containers making sure to label each one. Any material that does not pass through the sieve can be used in the garden. It will be of little use for pot culture.

Only after being sieved are these fertilisers individually weighed and mixed together in the proportions indicated below. When mixed they must again be stored in a waterproof container. It is interesting to note, I have never seen written, or discussed, the fact that any added fertilisers, mineral or organic, should be carefully graded before use with potting composts. If this point is not adhered to, it will create an imbalance in the release of nutrients which will adversely affect the plants development. Any material, mainly organic, that will not pass through a flour sieve is too large to incorporated in potting composts. It will take too long to degrade to be of any use and should be used in the garden.

The base fertiliser is comprised of the following ingredients which must be passed through a flour sieve before mixing and using.

  1. Unfortunately Hoof and Horn grist which I have used for many years is no longer available due to previous outbreaks of foot and mouth disease in cattle. I now use 500 grams of Blood, Fish and Bone fertiliser to replace the Hoof and Horn and have found this to be excellent. Remember to pass this material through a flour sieve before being used to remove the larger grist which will be useless for pot plants.
  2. 500 grams of Super Phosphate of lime for root formation.
  3. 375 grams of Sulphate of Potash. Formation of fruit & flowers.
  4. 250 grams of Steamed bone flour or fine bone meal. A valuable slow release organic form of phosphate which includes trace elements.
  5. 60 grams of Magnesium Sulphate, a trace element.
  6. 60 grams of Manganese Sulphate, also a trace element.

Only after weighing are the following fertilisers mixed together. Keep them dry in a waterproof container. Do not mix lime / ground chalk to these fertilisers. Keep it separate in its own waterproof container.

If Manganese Sulphate is difficult to obtain try the local chemist. It can be bought from specialist horticultural re-sellers. If unobtainable don't worry, there will probably be some provided in the other elements.

Compost composition. To each bushel of compost add coarse grit and perlite in the proportions outlined above. Then to each 40 litres add the base fertiliser in one or other of the following proportions. The amount depends on the size of pot, basket or container to be used. A set of accurate scales is essential.

Strength 1. For rooted cuttings or potting small plants into 7.5 cm to 9 cm pots. Add 120 grams of base fertiliser, and 30 grams of lime.

Strength 2. Potting on plants into 10 cm to 13 cm pots. Add 240 grams of base fertiliser. 120 grams of Seagold, organic calcified seaweed and 60 grams of lime.

Strength 3. Potting on plants into 15 cm. pots and above , baskets and large standards add 360 grams of base fertiliser, 180 grams of Seagold and 90 grams of Lime.

After weighing, add the base fertilisers to your compost. Mix well and leave for 24 hours before use.

NB: Seagold is a brand name for calcified seaweed. It is extremely alkaline and used to help correct the acidity, pH of added fertilisers. It is also extremely rich in trace elements iron, sulphur, boron, manganese and molybdenum and many others. It degrades slowly. With several other top showmen, I was asked to test this product. The consensus was, the colours and quality of the flowers were noticeably better when calcified seaweed was added to the compost.


Using this compost formula with the added fertilisers it should only be necessary to feed pot plants when they are in their final pots and becoming root bound. Do not feed prematurely, it will only poison them. If your plants lack vigour or have small undersized leaves knock them out of their pot and check the root system. Only if the roots healthy and starting to run round the inside of the pot should supplementary feeding be considered. If you do decide the plants need additional feeding use a high nitrogen or balanced feed, never high potash. Obvious signs of potash poisoning are small undersized very dark green leaves and small, sometimes malformed flowers. It will also over ripen the wood which is the main cause of plant failure the following year. If plants do survive the wood will be so hard bud development will be impaired. If there is a need to feed use a high nitrogenous fertiliser such as Urea. Urea, unlike Sulphate of Ammonia, leaves no toxic residue to build up. For the novice grower or those who only grow for pleasure, it would be far more prudent to feed with a balanced liquid feed with an N.P.K. of 7 7 7. at half the stipulated amount. Ensure it contains trace elements.

My show plants, once root bound, would be fed once a week with Urea. It would be diluted one heaped teaspoon to five litres of water. Nitrogen is most beneficial when used correctly. It promotes leaf growth, which can loosely be described as the plants stomach. The leaves, using photosynthesis, convert the neutralised fertilisers into sugars and starches for leaf and flower production. Never feed a sick plant. If the leaves lack lustre and droop check the plant for water. If this is present check the root system. If they are starting to turn brown, obviously dying, they are probably being attacked by fungi. Allow the compost to dry out then carefully re-pot in fresh compost. Hopefully it will survive.

If during the summer you are unable to grow plants outside it is essential to provide good air circulation. Keep all doors, windows and ventilators open whenever possible. Consider installing a fan. In addition to the chill factor, it increases the availability of oxygen and other essential gases essential for the process of photosynthesis. In still air this is depleted very quickly and can adversely affects your plants.


The art of watering is a science. Avoid watering a little and often this is rarely successful and encourages the root system to stay at the top of the compost. The compost at the bottom of the pot will quickly turn sour killing any roots that try to penetrate it. If your plants fail to grow as expected always check the root system. Poor growth is usually misinterpreted as lack of nourishment.

Before watering your plants, check the air temperature and ensure that the water temperature is equal to, or higher than the air temperature. If the water is cooler than the ambient air temperature it will lower the compost temperature which in turn will reduce the ability of the micro organisms in the compost to break down the fertilisers into compounds the plant uses for food. The organic fertilisers especially require micro organisms to break them down. They convert them into substances the plant can use. If the compost temperature is constantly reduced using cold water the production of plant food will be impaired. The plant will starve even though there is an adequate supply of fertilisers in the compost. The maxim is, always use warm water during the winter and early spring.

During the summer months when day temperatures are high, the night temperature is invariably very cold. During the night heat in the compost dissipates cooling it to a point where the micro organisms capacity to break down the fertilisers is reduced to a minimum. This process is natural progression. With daylight and subsequent rise in temperature food production increases.

However, if during the night the temperature drops too low, it will take a considerable time for the compost to warm up and activate the micro organisms into breaking down the fertilisers. Consequently the production of plant food is reduced and growth inhibited. In these conditions it is a good idea to keep your plants warm at night by double potting, using a slightly larger pot as insulation. In addition to keeping the compost warmer during the night, it will prevent overheating during the day. If direct sunlight falls on plant pot it can raise the temperature to an extent where it will burn the roots. All my show plants grown outside were double potted for protection. If possible, use a pot two sizes larger, place some sand or gravel in the bottom. Put your plant, in its pot, inside and fill the sides with sand. This will stabilise fluctuating temperatures in the compost, keeping it warm at night, cool during the day. It also helps reduce evaporation. This article is designed to highlight some of the problems which can be encountered when growing in pots. Understanding composts, feeding and watering is one of the keys to success.

A final reminder, remember all additional nutrients must be passed through a flour sieve before adding to your compost. Add lime separately, never mix it with other organic material.

Have fuchsias have fun.

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