How To, Jorge, Planting, Plants, Trees

Bare root plants in winter pose challenges to growers and gardeners alike. Freezing temperatures make even the simplest tasks difficult, with nurserymen having to trudge for miles in the bitter cold to assess whether a plant is suitable for transportation. Facing staff shortages and delayed couriers due to severed transport connections and hazardous rural roads, fulfilling orders can be beset by delays. Gardeners face different challenges with rock hard ground making planting impossible, rendering plants brittle and vulnerable to damage.

During winter plants become dormant, transfering energy to their roots and shedding their leaves. Biological activity slows, but doesn’t stop, just like when animals enter hibernation. This allows plants to be removed from soil that provides support, nutrients, warmth, moisture and oxygen. This reduces the weight of the plant, reducing transport costs, making bare root plants significantly cheaper than alternatives.

Plants can survive for significant periods without soil and can even be grown without as in the case of hydroponics. Although they can suffer for transplant shock, in which the plant’s health is threatened due to broken roots, disturbance and dehydration.This is why plants are carefully wrapped and their roots covered in hydrogel. Hence, they should not be removed from their wrappings until you are ready to plant and be left alone in a location not liable to temperature fluctuations.

Bare root plants should never be left in direct sunlight, nor be taken into the house, but can be stored in a cold outbuilding. Plants are liable to tissue damage when warming too fast, just like when humans suffer from chilblains. Bringing a plant into the house can cause the plant to come out of dormancy.

Bare root plants can survive for up to ten days without additional nutrients and water and indefinitely in temperatures below zero. If you are unable to plant in this time we’d recommend you leave your plant in water with liquid fertiliser. You can begin planting when the ground defrosts and temperatures rise above zero, with optimal temperatures around midday. Be sure to give your plants roots a good watering.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

How To, Jorge, Mice & Rats, Pest Advice, Pest Control

Rats in the loft are a worrying sign for any homeowner due to their propensity to spread disease, damage property and steal food. Worse, rodents in the loft indicate that they have spread deep into the property, forming a network throughout your walls. To deal with rodents it is can be useful to first identify the type of rodent before addressing structural issues and then dealing with the rodents themselves.

Types of Rodent

In the UK, the most common type of rat is the brown rat, followed by the black rat a distant second. As omnivores, these rats will consume nearly anything and are fond of burrowing; hence, in urban areas they will enter properties for shelter and warmth, which usually occurs at the end of the summer and autumn when the weather starts to turn. Of the two, the black rat is incredibly agile and can often be found inhabiting the upper areas of buildings, while the brown rat is more likely to stick to lower levels.

The two rats can be distinguished by their length, weight, body proportions and facial features with the brown rat significantly larger (40 vs 24cm long) and heavier (500 vs 200g) with small ears and eyes and a slanted snout. By contrast, the black rat possesses large ears and eyes and a pointed snout. Unsurprisingly, its body is slender with its tail longer than the rest of its body, hence the difference in weight. The brown rat is the opposite with a thick body and tail shorter than the rest of its body.

brown vs black rat comparison
Rattus rattus is the scientific name for the black rat, and Rattus norvegicus for the brown rat. Picture credit: Sponk licensed under CC BY-SA 3.0.

Of mice, the most common species found in UK homes is the house mouse followed by the closely related field and yellow-necked field mouse. The house mouse is particularly problematic as it can enter dwellings at any point of the year. Concentrated in rural areas, the field mouse will rarely enter homes, although may pose a problem to farm buildings. The house mouse can easily be distinguished from the field mouse by its colour with the former grey and the latter a sandy-orange.

A visual comparison of the field (L) and house mouse (R). Note the difference in colour. Picture credit: Hans Hillewaert licensed under CC BY-SA 3.0.

Significantly smaller than rats, mice can survive on a mere 3 grams of food a day and even go without water for significant periods. They are all excellent climbers and can multiply quickly. The house mouse, for example, can produce up to 8 litters a year with a gestation period of only 30 days. Hence, we recommend you act quickly to solve any rodent problem.

Safety Precautions

Rodents carry a wide range of diseases, some of which are deadly and others airbourne. Hence, other than wearing gloves and using a facemask, we recommend you air out any space before removing carcasses or excrements.


Rodents are usually identified by their droppings or the sound of crawling, scratching and gnawing, although can also be identified by chewed wires or pipes. In general, rats are more audible than mice and you are less likely to hear the latter crawling. Brown rat’s droppings are the largest between 1.5-2cm, black rat’s up to 1.5cm and mice less than 0.75cm. If you are having trouble locating your intruders, you can use rodent tracker dust to identify their comings and goings and aid trap placement. 

Addressing Structural Issues

Rodents, along with other pests, can enter your property through small cracks in the brickwork. They can enter your property through climbing shrubs and trees, and black rats may enter your loft directly. Hence, we recommend you seal any cracks with insulation foam and cut back overgrown plants. Rodents will often first take interest in a home due to overgrown gardens and easy access to waste. Hence, it is important to keep your rubbish tidied away.


Primrose has over 10 years’ experience developing pest control products and offers a large range of solutions to rodent infestations, divided into clinical and humane solutions. Of all our products, we’d recommend ultrasonic repellents. They work by emitting ultrasound waves, inaudible to humans, but painful for rodents, who use this frequency to listen for predators. Disturbed, they will move out of the vicinity of the sound. We offer both battery and mains powered repellents, of which the former can be useful if you do not have a socket in your loft.

Our battery-powered ultrasonic rodent repeller is perfect for lofts and camouflages as a smoke alarm.

Clinical solutions include mouse and glue traps. In the vast majority of cases a mouse trap will kill a rodent instantly, so they are humane in a sense. Glue traps are extremely effective and work great in tandem with conventional traps. However, the major problem with clinical solutions is that they rarely provide a long term solution as killing existing rodents simply makes room for new ones. Hence, we recommend you start with any ultrasonic repellent, before moving onto these solutions.

If you are using ultrasonic repellents, it is important to first give it time to work and then seal cracks in your property to allow room for the rodents to escape. If you plan to just use just clinical solutions, it is important to first seal your property. Ultimately, it can be useful to use all three solutions in tandem that have proven to be highly effective in dealing with the worst problems, and significantly cheaper than relying on professional pest control solutions.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Gardening, Grow Your Own, How To, Jorge, Planting, Plants

Growing your own goji berries is an excellent way to reduce your carbon footprint, save money and provide a source of nutrients for your family. High in vitamin C, B2, A, iron, selenium and the antioxidant polysaccharides, they constitute a welcome addition to a balanced diet and are great as part of a smoothie, or served with oats. Growing goji berries is relatively easy as it is well adapted to the UK’s climate as with other himalayan species.

Growing goji berries from seed is not recommended as seeds are prone to rot and seedlings require warm conditions for 12 months, which is both impractical and costly. Hence, we recommend two year old plants that are winter hardy and ready to fruit. It you do wish to grow from seed, rot can be prevented through an irrigation system ensuring moist soil. Goji berries work well in containers and normal advice applies.  

Soil and Sun Requirements

Goji berries are from the solanaceae family and possess a similar nutrient requirements to tomatoes. Hence, as nitrogen hungry plants we recommend applying fertiliser at the start of the growing season. However, as they are sensitive to salinity, we recommend avoiding inorganic fertiliser, which contains soluble salts. Compost also contains salts, so should be a small proportion of the potting mix (20%). Goji berries require full sun, but also benefit from shelter. They work well as hedges and possess delicate white and purple flowers, so function well as an ornamental.


Mature plants can reach 3m high and 1.5m wide. Hence, we recommend they be spread at 1m apart. As with all potted plants, it is important to keep the soil ball intact and ensure it is planted at the same depth as it is in the container. (Using a spirit level or ruler can help you keep it is level.) This will ensure the roots are within range of the nutrient rich top soils, but not exposed as to lead to air pruning. We recommend you dig a hole bigger than the circumference of the container and fill it with a mix of fertiliser, compost and garden soil, which is superior in structure and nutrients to garden soil. Be sure not to pack the soil too tight or compress the soil as this will reduce retard root growth. Once this is complete be sure to water thoroughly.

Next, you are to remove all nearby plant life and mulch. By doing this you are reducing competition, allowing the growth of a healthy root system, and improving the soil’s structure, which gives the plant access to air and water. Mulch should not come into contact with the shrub’s main stem as to ensure it does not come diseased, and be level with a depth of 2 and 3-4 inches for fine and coarse materials respectively. Mulch can be replenished annually, depending on the material, and the area it covers should be increased as the shrub’s roots expand.


The most important function of pruning is to remove old, dead and damaged stems to make room for new stems. (Flowers and berries are borne on stems grown in the spring and autumn of the year before.) By pruning stems you encourage the production of more laterals, leading to higher yields. Pruning has the additional advantage of increasing sunlight penetration and improving foliage drying, which is especially important with goji plants susceptible to verticillium wilt. Hence, it is also important to water at the base of the plant. We recommend watering thoroughly, every so often, rather than little and often, as this will encourage the formation of deep roots, which helps the plant endure dry periods. Pruning should take place in the spring, just as the plant starts to grow.


Goji berries produce the biggest yields in their fourth year, while at two you can expect a kilo of fruit. To harvest, wait till the fruit is deep red and fully ripe (usually midsummer), and then shake them onto a blanket. Handling can make them turn black. To dry goji berries, leave them on a sheet of baking paper in a cool, dry spot out of direct sunlight.

If you are interested in growing your own goji berries, Primrose offers two year old goji berry plants from just £4.99.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Composting, How To, Jorge, Planters, Planting

The amount of compost needed for a planter depends both on planter size, its material and the plant you wish to grow. Compost is important as it will improve your soil’s structure, increasing its available water capacity (AWC), which is especially important for planters. Calculating a planter’s volume (measure in litres) is relatively easy, but it is first important to work out the compost/garden soil ratio required for a particular plant.

Compost/Garden Soil Ratio

Now why do I want to mix compost with garden soil? Firstly, garden soil is incredibly complex with numerous soil organisms that help boost your plant’s health. These organisms will help improve the structure of your soil and break down organic matter into mineral nutrients, available for uptake by plants. However, there is the possibility of inducing pests and diseases, so we recommend avoiding soils that you have previously planted. Secondly, garden soil will help improve drainage, ensuring your planter does not become waterlogged. Lastly, using garden soil will save you money and lower your environmental footprint.

While compost does add nutrients to the potting mix, its major advantage is improving the water-holding capacity of the soil, which occurs through two mechanisms. Firstly, compost contains carbon, as well as other nutrients, that provide food for soil organisms. These organisms function to increase a soil’s porosity – the percentage of soil that is pore space or voids. Secondly, compost improves soil structure by gluing tiny particles of rock (sand, silt, or clay) together into peds (aggregates), which is the basis of all good soils. These peds have adequate pores to allow entry of air and water, both which are essential to plant health. The increased porosity has its origin in the fact compost is significantly lighter than conventional soils.

An ideal soil has a porosity of about 50%, equally divided between micro and macropores, which provides a good mix of drainage and retention. When it rains both macro and micropores become filled with water. Larger pores are the first to drain with light sandy soils taking about a day and heavy clay soils about three. Micropores remain filled and are unaffected by gravitational flow, the water held by electrostatic attraction. The smaller the pore, the more tightly the water is held. Macropores drain too quickly to be of much use to plants, providing little water, but allowing flows of oxygen to plants’ roots. Micropores retain water, available for use by plants. Hence, macro and micropores complement each other, allowing air and water to reach plants’ roots.

Picture credit: MesserWoland licensed under CC BY-SA 3.0.

Fascinatingly, small pores act to draw groundwater up through the soil, providing a source of water in the absence of rain. This phenomenon occurs due to the forces of cohesion (propensity of water molecules to stay together) and adhesion (propensity of water molecules to stick to other surfaces). When the force of adhesion is greater than that of cohesion the water rises, with the water near the edge of pore curving upwards. Capillary action can be easily demonstrated by dipping a paper towel in water and watching water climb the towel.

Soil textures – clay, sand, silt and loam – each have different drainage profiles, originating from the size of the particles. Clay particles are the smallest, sand the largest and silt in between. The larger the average particle, the faster the soil drains. Loam is comprised of about 40% sand, 40% silt and 20% clay and is considered the best texture, having the optimal balance of micro and macropores. Clay lacks larger pores, providing poor aeration and drainage, and possesses minute micropores too small for plants to utilise, reducing the soil’s available water capacity. Sand, on the other hand, drains too quickly, predominantly composed of large pores.

Compost increases the number of micro and macropores in the soil, greatly improving a soil’s available water capacity, and should be added to all soil textures including loam. B. D. Hudson’s 1994 paper demonstrated that for every texture as organic matter was increased by 1-3%, the available water capacity doubled. A 2000 study by A. Maynard found that the amount of water in a plow layer (8 inches) increased from 1.3 to 1.9 inches in soil amended with compost, providing a two week supply of water for vegetables, significantly reducing water stress.

An increase in the available water capacity is especially beneficial for potted plants that receive significantly less rainfall due to their container’s small surface area. We recommend the potting mix contain 20-50% compost with higher blends if your soil is clay, your plant thirsty, or the planter’s material porous as with terracotta. Compost will not provide all the nutrients needed, so we recommend the application of organic fertiliser. Mulching is also useful and will help improve water retention and soil structure.

Calculating Volume

A 1 litre cube. Picture credit: H McKenna licensed under CC BY-SA 2.5.

Volume is the sum of 3 measurements (length, width and depth) multiplied together and is expressed in cubic units (cm³, m³). Cubic units correspond directly to litres with 1 litre equal to 1000cm³.

Most planter retailers will give you the dimensions of a planter in cms that can be used to calculate volume. In not, you can use a tape measure. Compost is sold either in litres (l) or cubic meters (m³).

Note: most planter dimensions provided online will be the outer rather than inner dimensions, so you’ll need less compost, depending on the thickness of its sides.

Note 2: planters come in a huge range of shapes. Hypothetically you can calculate the volume of any shape (done by dividing shapes into smaller ones), but we recommend you simply approximate the shape.

Once you have calculated your planter’s litres, simply times it by 0.2-0.5, depending on how much compost you wish to add, to arrive at the quantity you need to buy.

Cubes and Rectangles

Calculating volume for cubes and rectangles is very easy. Simply multiple width, depth and height and then divide by 1000.

Hence, a 100cm³ planter would have a volume of 1000 litres. (100 x 100 x 100 / 1000.) A 140 x 30 x 30 rectangle would have a volume of 126 litres. (140 x 30 x 30 / 1000.)


Calculating the volume of a cylinder requires multiplying height by radius squared by pi which is written as V =πr²h. You then need to divide by a 1000 to get volume in litres. Hence a planter with 30cm diameter and 30cm in height would have a volume of 21 litres. (3.142 x 15² x 30 / 1000.)


To calculate the volume of a bowl, you have to calculate the volume of a sphere and divide by 2. Calculating the volume of a sphere requires multiplying 4 divided by 3 times pi times radius cubed, which is written as 4/3πr³. You then need to divide by a 1000 to get volume in litres. Hence a bowl with a 15cm radius would have a volume of 7 litres. (((4/3 x 3.142 x 15³) / 1000) / 2.)

If you would like to know more about soil science please read our guide: Everything you need to know about soil.

If you are interested in pots, Primrose has the biggest range online with over 2000 planters. We also sell compost starting at £5.99.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.