Bulbs, How To, Jorge, Planting, Plants

To plant bulbs successfully, it’s important to plant at the right time and depth with the bulb the right way up. You can ensure showstopper blooms by fertilising when planting, and as long as there is vegetative growth in the growing season. Applying mulch in winter will help protect spring-flowering bulbs from frost injury. 

When To Plant

If ordering online, plant as soon as you receive the bulb, or store in a dry, dark location if you can’t plant immediately. Leave a bulb unplanted and it may fail to flower or flower poorly. If you forget to plant, examine by touch, and discard soft or rotten bulbs. Others are worth a shot. 

Generally, spring flowering bulbs need to be planted by the end of September, which will allow time for the bulb to root before the ground freezes. Tulips are planted in October and November, depending on whether you are in the North or South respectively, which helps reduce problems with disease. 

Hardy summer flowering bulbs are to be planted in September and October, while tender summer flowering bulbs in early spring. Autumn flowering bulbs need to be planted by late summer. 

BulbSeasonPlanting depthPlanting distance between bulbsPosition
AlliumAutumn10cm (4″)10cm (4″)Full sun
BegoniaSpring1cm (1/2″)30cm (12″)Full sun, semi shade, dappled shade
CrocusAutumn10cm (4″)7cm (3″)Full sun, semi shade
DaffodilAutumn10cm (4″)10cm (4″)Full sun, semi shade
DahliaSpring15cm (6″)45cm (18″)Full sun
BluebellSpring/Autumn10cm (4″)10cm (4″)Dappled shade
GladiolusSpring10cm (4″)15cm (6″)Full sun
HyacinthAutumn10cm (4″)8cm (3″)Full sun, semi shade
Iris reticulataAutumn10cm (4″)8cm (3″)Full sun
LilyAutumn20cm (8″)15cm (6″)Full sun, semi shade
NarcissusAutumn10cm (4″)10cm (4″)Full sun, semi shade
PonerorchisSpring2.5cm (1″)7cm (3″)Dappled shade
RanunculusAutumn8cm (3″)25cm (10″)Full sun
SnowdropSpring/Autumn10cm (4″)10cm (4″)Dappled shade
Tree LilyAutumn20cm (8″)15cm (6″)Full sun, semi shade
TulipAutumn15cm (6″)13cm (5″)Full sun
White Egret OrchidSpring2.5cm (1″)7cm (3″)Dappled shade
Winter AconiteAutumn5cm (2″)5cm (2″)Full sun, semi shade, dappled shade

Position 

As always it’s best to look at a species habitat and flowering time when deciding where to plant. Early spring bulbs such as snowdrops are used to harsh conditions, and will thrive in cold pockets. Forest dwelling species such as the bluebell are used to dappled shade, and will thrive under any deciduous tree. More exotic species such as dahlia, originating from Mexico, are suited to full sun. 

It’s not the end of the world if you plant in a sub-optimal location as bulbs are a storage organ and the plant already has a large reserve of energy. Bulbs rarely thrive in deep shade and output will be poor in the second year after planting. 

It’s possible that southern exposure can lead to early emergence and freezing injury. You can moderate temperature extremes by applying 3 inches of mulch after the first frost. This will help prevent injury from the constant cycle of frost and thaw. Remove the mulch if you think the shoots can’t penetrate it easily. 

Mulch will help protect bulbs from frost injury.

Soil Type

The key message is to avoid waterlogged soils, which can starve a bulb of oxygen, causing them to rot. Clay soils usually have poor drainage, and can be improved by adding organic mulch. Ensure you don’t compact the soil, but firm with the back of a rake. 

Right-side Up 

Most bulbs have a tip, which should be pointing upwards when planted. Some will arrive with roots on the bottom, opposite to the tip. Begonia bulbs do not have a sharp point, but you can sometimes detect the tip emerging out of the concave (indented) side.

Planting Depth & Distance

A general rule of thumb is that bulbs can be planted three times their height, although begonias are an exception to this. 

Bulbs in containers can be spaced a bulb width apart. In the ground, 2-4 inches is common for small and 8 inches for large bulbs. 

Apply phosphorus when planting as it doesn’t travel well in the soil. This essential nutrient helps with root growth. 

Aftercare

Water immediately after planting, unless you are planting in autumn and the ground is already wet. 

Sometimes, small mammals will dig up bulbs, but this can be prevented with wire mesh. 

Plants in containers are vulnerable to drought and under fertilisation, so water and feed regularly once the growing season starts. 

As nutrients are absorbed through roots, it’s important nutrients reach the depth the roots are located. Liquid fertiliser will penetrate the soil, and can remedy deficiencies quickly, but is liable to leeching. Other inorganic fertilisers will fertilise the soil over time, so need to be applied in advance. Organic fertiliser takes far longer as it’s insoluble and first needs to be broken down by microorganisms, before becoming available for uptake by plants. 

Removing seed pods, but maintaining foliage, allows a plant to put more energy into its bulb, for larger blooms thereafter. Watering and feeding will help with this. Remove foliage once it yellows. 

After this, bulbs can be lifted, sorted, washed, left to dry and then stored in a cool, dry, airy place. Small, rotten or diseased bulbs are best thrown. 

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.

Indoor Plants, Jorge, Plants

Most house plants require very little attention, with regular, but infrequent, watering and annual or biennial repotting.  

Watering & Humidity Requirements

The key is not to overwater as to cause root rot and plant death. Watering when soil is dry, or almost dry, is a good rule of thumb. It’s important to push your finger into the soil to check for moisture, as soil may appear dry but be wet underneath. 

It’s surprising how long certain species can survive without water. Succulents, of course, have various morphological characteristics that allow them to store water and reduce transpiration. 

You may remember epiphytes from biology class, such as lichens, which are not a single organism, but two in a symbiotic relationship. Epiphytes grow on the surface of other plants, and most do not root in soil. Instead, they absorb water from the air. Some species of orchid, including the popular Phalaenopsis, are epiphytes. One egregious example, such as some species of Tillandsia, also known as the air plant, have minimal root systems and grow on shifting desert soil. 

Even houseplants that do root in soil, such as Zamioculcas, most are drought resistant. If you are ever unsure about a plant’s watering requirements, first check a supplier’s website. You can also make assumptions based off a plant’s climate. Species from rainforests benefit from high humidity, and those from deserts low. Also, what morphological characteristics does the plant possess? A plant with lots of thin leaves will lose water faster than one with thick, leathery, waxy, or hairy leaves, and one with no leaves at all. 

You can tell when a plant is suffering from too little water as it will first droop and then wilt. Don’t give up. Just because a plant is wilting doesn’t mean it can’t be revived. All that is happening is that the cells have depressed and the plant become slack. When watered, its cells fill up and the plant becomes taut. So, give it a thorough watering and watch it spring to life. 

Plants in small pots (succulents excluded) do need monitoring as small pots have a tendency to dry quickly. It’s best to repot and when you do, ensure you don’t compress the soil. Otherwise, the soil is liable to becoming waterlogged. 

Plants can die from insufficient watering and it’s usually because of gas embolism. Normally, plants absorb water through its roots, which travels up through the stems to the leaves. In times of drought, plants will sometimes absorb air that can form a bubble, which blocks the flow of water upwards. 

Certain species, especially those from rainforests, benefit from high humidity. Humidity is important as the lower the humidity, the more water is lost to evaporation. Temperature affects the amount of water air can hold, so more water is lost at higher temperatures. 

Greenhouses are low humidity and perfect for cacti.

Humidity can temporarily be increased by misting – spraying plants with water. Preferable, is putting plants on a drip tray covered in pebbles and filling the tray with water, which will evaporate at room temperature, creating a nice microclimate for your plant. If you drill a hole in your pot, it will help with drainage, and excess water will fill the tray anyway. You can also try grouping plants together and planting plants in terrariums, from which water can’t escape.

You can measure humidity by purchasing a thermo-hygrometer, which measures relative humidity. It will give a reading in as a %, because at say 75% relative humidity, the air can hold 25% more water at the same temperature. Once you have worked out each room’s humidity, you can put your plants in the room they are best suited. 

You can tell when a plant is suffering from low humidity as it’s leaves will begin to curl, as to reduce the surface area exposed to light. Plants are unlikely to suffer from high humidity, but from pests and diseases that multiply in conditions of high humidity. 

Light Requirements

Plants need light to kickstart photosynthesis – a process whereby sunlight, water and carbon dioxide is converted into glucose and oxygen. Glucose is used by the plant in numerous key functions such as metabolism and growth, and is also stored as starch. 

Most house plants are well suited to poor lighting and will suffice in substandard conditions. However, it’s best to reserve bright rooms for plants selected for flowering, fruiting or variegated foliage, as these processes will overwise be inhibited. 

Certain species are sensitive to sunlight hours. Some will only flower when the days are long and others when the days are short. Keeping these plants near windows, and away from artificial lights will help with flowering. Others are day neutral, unaffected by day length.

Poinsettias are one fascinating example of photoperiodism – the response of an organism to day length. The species has evolved to cease the production of chlorophyll and initiate the production of anthocyanins in response to shortening days, resulting in its leaves going from green to red, in the aim to attract pollinators to its tiny flowers. You can initiate this transformation yourself by putting the plant in total darkness for 3 months 14 hours a day. 

It’s important to give your plants a period of darkness (at least 8 hours). At night, plants respire, taking in gases used in photosynthesis in the day, and also break down glucose produced in the day in maintenance and growth. (In the day, plants close their openings to reduce water loss. Hence, while plants produce energy in the day, they use it at night.) 

Certain species, such as many epiphytes, aren’t adapted to direct sunlight and may pale, brown and die from too much exposure. Simply, move to a darker location. 

Plants do not absorb all wavelengths of light equally, with the main pigments involved in photosynthesis (chlorophyll) primarily absorbing blue and red light with green reflected. (This is why plants appear green to your eyes.) 

Picture Credit: Daniele Pugliesi (2008) modified by M0tty licensed under CC BY-SA 3.0.

Artificial lighting can be absorbed by plants, but is composed of different wavelengths than natural light. Incandescent lighting produces mostly red light, while fluorescent and LED light varies. LED lights are often divided into cool and warm variants, with the cool emitting more blue and warm more red. 

You can grow plants exclusively under artificial light, say in a basement, but it’s important to get the colour balance right, otherwise flowering, variegation and growth will be affected. 

High intensity blue light will promote the flowering of long day plants and inhibit that of short day plants. Likewise, even low intensities of red light exposure at night will inhibit the flowering of short day plants and promote the flowering of long day plants. 

Blue light is important in promoting leaf colouration. Varieties with purple leaves may go green in its absence. A dearth of red light will result in spindly growth and a dearth of blue light stumpy growth. 

Light intensity decreases as the distance from the source increases. It is for this reason window direction affects the intensity of natural light received. Windows facing east and west receive about 60% of the intensity of southern exposure. Northern exposure a mere 20% of southern exposure. 

A room’s light intensity is affected by the colour of a room’s surfaces (with lighter colours reflecting light and producing brighter rooms), and the transmission of natural light, whether it’s blocked by outside objects, curtains/blinds or dirt on windows. 

Often blinds are closed and curtains drawn in the day, but don’t forget your plants need light.

Light intensity varies throughout the seasons. In summer, window sills are bathed in light, as the sun rises quickly and is mostly high in the sky. In winter, natural light actually penetrates interiors further as the sun stays low in the sky. 

Insufficient sunlight leads to etiolation, whereby a plant grows spindly with long gaps between nodes – areas of the stem where leaves are located – and chlorosis, whereby leaves turn yellow, caused by the death of chlorophyll. Both these effects make evolutionary sense, allowing the plant to stretch in search light and forgo wasting energy on useless leaves.

It is possible to measure light levels, but you’ll need a camera. The process is detailed here.

Temperature 

Temperature speeds up respiration, causing plants to break down glucose faster. Glucose is produced from photosynthesis, which is a function of light intensity, duration and composition. 

First, glucose is used in maintenance and then, if there is some spare, growth. Hence, growth increases with more light and higher temperatures, and slows with less light and lower temperatures.

If a plant has insufficient glucose for maintenance, it’s cells break down and it eventually dies. To combat this, you can either raise light levels to increase glucose production or reduce night time temperatures to reduce glucose consumption.

Cooler night time temperatures benefit many plants, as it is in this period they exchange gases and release water. If temperatures are too high, a plant may fail to open its pores, causing it to suffocate/overheat. Switching your heating off at night will benefit most plants.

House plants from tropical and subtropical climates, where there are small variations in day/night temperatures, and equatorial climates, where there is no seasonal fluctuations, but not those from deserts, where the nights are very cold, are liable to chilling injury. These plants are simply not adapted to low temperatures and can’t change their respiration rates. 

Spraying your tropicals with cold water can send them into shock.

Sudden exposure to cold is worse than gradual and can lead to rapid chilling injury, so try to keep temperatures consistent. Keep your plants away from draughts and place in rooms where temperatures fluctuate the least. Don’t water tropicals with cold water. 

Nutrition 

Nutrition is important, but if you have a problem with your plant, it’s likely down to sub-optimal lighting, humidity, watering, or temperature. 

Diagnosing nutrient deficiencies from visual examination is challenging and soil testing is necessary for certainty. There are five symptoms caused by nutrient deficiencies: stunted growth, chlorosis (yellowing of the leaves), interveinal chlorosis, purple-red colouring and necrosis, although these are also caused by other factors including nutrient toxicity. 

The development of symptoms help rule out certain factors. Some nutrients are immobile and can’t travel from old to new growth, while others can. Thus, if the symptoms are localised, it will be an immobile nutrient, but generalised a mobile one. Montana University have developed a useful identification key from such information, on pages 6 and 7. 

Watering with tap water can lead to a buildup of salts.

Just like with watering, you can over-fertilise, as so nutrients become toxic. Build up appears as a whitish crust on the soil’s surface and around the rim of the container. (Watering with tap water will cause this also.) To remedy, flush the soil by gently watering, ensuring water flows out of the bottom. Like with deficiencies, the symptoms of toxicity are examined on page 13. 

Due to the complexities of diagnosing nutrient deficiencies, it’s best to follow rules of thumb. For example, if you want to grow your plant, you’ll want to apply fertiliser, but also put in a well lit area, as plants produce most of their energy from photosynthesis. Vice versa plants in well lit areas will need fertilisation. 

You’ll want to apply fertiliser in or before the growing season, depending on whether or not the fertiliser is slow release. During or before dormancy, fertiliser is unnecessary. Fertilisation should be based on the amount of soil and size of the pot and the species. Fertilising slow growing succulents is unnecessary, but is useful for fruit maturation (i.e. with chillies). Fertilise after watering and never before, as water will wash away nutrients, but is necessary, as most nutrients absorbed is dissolved. 

Repotting

Key is not to compact the soil as compaction will stop air and moisture reaching plants’ roots. Contrary to popular belief, you don’t need specialist compost, although it’s preferable. Different materials exert different effects on plants. Terracotta is famously porous and drains faster than non-porous materials. Recently, I planted my chillies in a mix of terracotta and plastic pots, and made the mistake of watering them at the same time. The terracotta pots’ soil would be bone dry and the plastic pots’ moist. 

Acclimatisation 

Every plant will adapt to its conditions, but adaptation takes time. Commonly, house plants are moved outside in the summer months, put on a flush of growth, and are then moved back indoors, and start to drop leaves. The plant simply can’t produce the energy to support the sun leaves and will produce less energy intensive shade leaves. Changing light levels is rarely fatal, but changes in temperature is. Outside winter temperatures are too low for many house plants, so ensure you house doesn’t get too cold. 

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, Plants

Currants and Gooseberries are all part of the Ribes genus. Jostaberry is a cross between two gooseberry species (R. uva-crispa and R. divaricatum) and blackcurrant (R. nigrum). White-currants (and pink-currants) are the same as redcurrants (R. rubrum).

Pruning takes place when the bush is dormant, ideally in late-winter/early-spring. Some may prune in late-summer to tidy up vigorous varieties. As always, practice makes perfect and over time you’ll learn what works best.

Gooseberries and redcurrants fruit on short spurs on 2-3 year old wood. Blackcurrants and jostaberries fruit at the base of 1 year old wood and on spurs on 2 year old wood. It is for this reason that 4 year old wood is removed for gooseberries and redcurrants, and 3 year old wood removed for blackcurrants and jostaberries.

You can easily identify the age of the wood by its colour. Older wood is often black/listless white, while the youngest is brown.

As usual the four Ds (dead, dying, diseased or damaged) should be removed.

Gooseberries and redcurrants can be grown as a freestanding bush (where you remove all suckers and branches originate from a single stem), a stool (where you allow multiple stems to grow from the roots), and as a cordon. Blackcurrants and jostaberries can only be grown as a stool as they need constant renewal.

Free-Standing Bush

With the free-standing bush method, you are seeking to establish a goblet shape with branches growing away from the centre. This allows light and air to penetrate the bush, reducing disease incidence and promoting ripening. Stems growing towards the centre are thus removed.

The buds you prune to should be based on the height and direction of your branch. Branches that grow upwards, prune to an outward-facing bud to encourage spreading. Branches that sprawl, prune to an upward-facing bud to encourage vertical growth. You are aiming for a 45 degree angle.

Branches too close to the ground should be removed. Laden with fruit, branches will droop down further. (Keep that in mind when selecting outward or upward buds.)

You’ll also wish to remove branches that cross (or grow too closely together) as rubbing can cause canker.

Suckers can be removed in summer and are best pulled than cut, which takes the growth node.

Formative Pruning

Nurserymen and women will shorten the main stems of your bush when it’s young to encourage branching. This will leave you with a plant with multiple branches growing off the main stem (known as the central leader). You’ll want to select 4-5 branches, 2-3 growing in one direction and 2-3 in the opposite direction, and remove all others. Ensure the branches on each side aren’t too close together. These branches are known as your primary scaffold.

In the first year, cut each primary scaffold to an upward facing bud.

By the second, the primarily scaffold will have branches growing off them (the secondary scaffold). Cut all branches back and select only upward/outward buds, depending on the height and direction of the bud.

By the third year, you’ll have a nice goblet shape.

Maintenance Pruning

Once you have established a goblet shape, prune to maintain it.

In winter, remove all low lying and dead, dying, diseased and damaged branches. Cut back new growth on branches by half and new growth on side-shoots to 1-3 buds. Side shoots growing towards the centre can be shortened to 1 bud to allow light to penetrate the interior.

Late June, shorten side-spurs to five leaves from the base.

Stool

The stool method bears some similarities with growing raspberries, whereby you allow suckers/stems to grow and then cut then right back down to the ground.

With the stool method, you want a mix of wood growing to ensure a good annual harvest. Thus with redcurrants and gooseberries keep a mix of one, two and three year old stems and with blackberries keep just one and two year old stems.

Usually 9-12 canes are kept with redcurrants and gooseberries, and 10-12 with blackcurrants/jostaberries. With vigorous varieties, you can have more stems growing at any one time.

It’s important you don’t remove suckers, but thin them, selecting the best. And just like with a freestanding bush, remove all low lying, rubbing and dead, dying, diseased and damaged branches.

Redcurrants/Gooseberries

In the first season of planting, keep 6-8 shoots.

In the second, leave 4-5 one year old stems and 3-4 two year old stems.

From then on, select 3-4 one and two year old wood and remove all third year wood, cutting 2 inches from the ground.

Blackcurrants/Jostaberries

In the first season of planting, keep 6-8 shoots.

In the second, leave 5-6 one year stems and remove all two year old stems, cutting 2 inches from the ground.

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.

Jorge, Plants, Trees

When deciding on a cherry fruit tree, you have to decide on how big you want your tree. Rootstocks determine the size of you tree with dwarfing rootstocks producing smaller trees. You then have to select a variety, ideally one you like the taste of. As many will not be familiar with cherry varieties, we have made some recommendations.

Introduction To Cherry Fruit Trees

Unlike other fruit species, it is recommended that you choose a self-fertile variety as your first tree as you can’t be sure of pollination otherwise. Once you have a self-fertile variety in your orchard, you can purchase any cherry in the same or neighbouring flowering group.

cherry pollination groups

Cherries are liable to cracking in heavy summer rains. Varieties with a resistance to cracking are recommended as you’ll receive an unblemished crop. Studies have shown that ‘Karina’ and ‘Regina’ exhibit high resistance and ‘Lapins’ moderate resistance.

Cooking (acid or sour) and dessert (sweet) cherries are actually different species: cerasus and avium respectively. They can still cross-pollinate, however.

Sweet cherries do not keep well and are best eaten fresh. This is why it is important to spread your orchard between early, mid and late cherries.

Unsurprisingly, traditional English varieties are actually from Continental Europe. Cherry production didn’t take off in England until the first half of the twentieth century.

Modern cherry varieties are primarily from Summerland research, Canada who started a self-fertile cherry program in the 1940s. They introduced the now classic Celeste, Stella, Sweetheart and Sunburst, which all start with an “S”-sound.

Cherries are often characterised as black or white, with black referring to the colour of the skin and white referring to the colour of the flesh. White flesh is associated with excellent flavour and common to traditional varieties. Black, or dark, skin is associated with modern varieties, which need be aesthetic.

Sometimes you will see cherries labelled Bigarreau, which refers to a firm-fleshed variety.

Cherries can be spherical or heart-shaped, although sometimes heart-shaped is broken down further.

Dessert

Lapins (sometimes known as Cherokee) remains the cultivar of choice. It is self-fertile, productive and its fruits are resistant to cracking. Sunburst and Sweetheart make excellent alternatives and will produce bountiful crops of delicious fruit.

Cooking

With cooking cherries, you have a choice of Morello and Nabella. Nabella is the new introduction, although Morello still retains RHS Award of Garden Merit. Both are self-fertile.

Dual Purpose

Look no further than May Duke, a self-fertile cross between acid and sweet cherries.

Best x Season

Celeste is the best self-fertile early season cherry.

Mid-season, you are spoilt for choice with Lapins, Stardust, Stella, and Sunburst.

Late season, there is a choice between Kordia and Sweetheart. Sweetheart has the best flavour.

For Small Gardens/Dwarf

Cherries with the dwarfing Gisela 5 rootstock are recommended for small gardens, which will produce a 3m tall tree. You can always prune your tree to reduce its size. Alternatively, buy a cordon tree, which is trained to produce a columnar shape.

Petit Noir, Hartland and Celeste are all naturally compact. Sylvia is as well, but isn’t self-fertile.

Unusual

Napoleon Bigarreau, Stardust Coveu and White Heart are all white cherries. Stardust is unique in that it is self-fertile. All these varieties have exceptional taste.

Cold Areas

Cherries with the Colt rootstock is recommended for cold areas as Colt produces a tree higher from the ground. Be sure to plant your tree in full sun!

Developed in the UK at the John Innes Research Station, Summer Sun makes an excellent choice for colder areas of the UK.

Productive

Lapins and Sweetheart are exceptionally productive cultivars. It is best to combine these varieties with Colt as Gisela 5 can overbear, leading to poor quality fruit.

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.