Primula


Primula obconica

Top Tips

  • Keep the soil evenly moist whilst in flower, using lukewarm water and the bottom-up method of irrigation.
  • Average room humidity is more than acceptable for Primroses - never situate it within three metres of an operating heat source to avoid dehydration.
  • Bright, indirect light is best - avoid direct sunlight and excessively dark locations for best results.
  • Supplement fortnightly using a potassium-based feed whilst in bloom, reverting back to a general plant fertiliser at monthly intervals, soon after.
  • Scroll down to the 'Dormancy Care' section to learn about annualising blooms.

∙Water - 🔸🔸

Throughout the blooming period, Primroses must be sat in moist soil for most of the time. Allow the pot to become slightly light in between hydrations, using the bottom-up method. Splashing the flowers and leaves each time you come to water the plant will result in the foliage beginning to rot. Place the pot on a saucer one water, around one quarter deep, until thorough absorption. You may have to repeat this twice a week if needs be, especially with those grown in bright, warm locations. Try not to use cold water during this period, to avoid shocking their tender root systems. Under-watering symptoms include rapid flower loss and dry, crispy leaves - these issues are usually due to either forgetfulness, too much sunlight or too much heat. Even though an under-watered Primrose is far better than a soggy one, never allow the soil to thoroughly dry out for too long as this could cause flower or leaf loss. Over-watering symptoms include rotting lower leaves, yellowing leaves, a loss of buds & flowers and root or crown rot. Allow most of the soil to dry out in between waters and prevent a pool of standing water accumulate beneath the pot.


∙Humidity - 🔸🔸

Average room humidity is more than enough to occupy a Primrose, as too high humidity and poor air circulation will result in powdery mildew. If your house is prone to dry air, introduce a humidity tray to provide a pocket of humidity, which in turn will help flora growth. Botrytis is caused when excess moisture is allowed to settle on the flowers that can spread quickly if not dealt with accordingly. For those displaying signs of this, be sure to click on the link below to learn how to address them.

Identifying Common Houseplant Pests & Diseases


∙Location & Light - 🔸🔸🔸

A location that offers a splash of morning or evening sunlight is the ideal setting. Shady locations must be avoided at all costs due to the heightened chance of over-watering and crown rot (if watered from above).

In terms of the ideal room around the house, as long as it's above 15ºC  (59ºF)  and is at least three metres away from an operating heat source, it should be accepted. Try placing the plant on a north, east or west facing windowsill, or at least two metres away from a south-facing one. It's important to provide a splash of sunlight to prevent the chance of foliage or root rot.


∙Fertilisation - 🔸

A general fertiliser, for example BabyBio or Miracle-Gro used at monthly intervals is ideal to improve the overall health. Supplementing the plant whilst in bloom isn't necessary, and may cause sudden flower loss if over-fertilised.




Common Issues with Primroses

Over-watering is the biggest issue when it comes to a Primrose. Typical signs of this include brown leaves with soft spots on the underside of the leaves, root/crown rot or powdery mildew forming in the centre. Not only do you have to be mindful of different rots, but also have a think about which plant parts to keep dry. Its central crown must also remain dry at all times to prevent the development of basal rot or mildew. For any more information about over-watering related issues, be sure to click on this link.

More than four hours of sunlight will lead to sun scorch, with typical signs including browning or crispy leaves, dry leaf-edges, sunken leaves or stunted growth. Although too little light will cause over-watering issues, too much sunlight will negatively affect the plant as well. A location that offers over two hours of sunlight a day will bring the optimum growth for the Primrose. If yours has fallen short of this issue, reduce the amount of sunlight considerably and always be mindful of environmental shock (when too locations offer too different growing conditions). Remove some of the affected leaves and increase irrigations slightly. Only hydrate the plant using the bottom-up method.

As mentioned before, powdery mildew and botrytis are major threats among heavy foliaged plants due to the compact nature that aids the spread of the diseases. Watering above the foliage will allow excess moisture to sit in the cubbyholes of the stem, enticing harmful bacteria to thrive. Remove the affected areas and improve the growing conditions by situating the plant in a brighter location with the use of the bottom-up method of irrigation.

Over-supplementing a Primrose whilst in bloom will bring nothing but grief in the likes of yellowing leaves and weak, dramatic growth. Although a monthly feed is an excellent way to promote healthy growth, the combination of dry soil and sharp chemicals will quickly lead to the burning of roots. The best advice for this issue is to pre-moisten the soil beforehand; not only will this remove the chemical-edge found in fertilisers, but it will also adversely remove the chance of damaging the roots.

A lack of flowers is caused by a insufficient dormancy period, served in the summer months. Locations that offer near-similar temperatures all year round won't allow the plant to go dormant, resulting in poor spring growth. To achieve, situate in a location that dips to around 12°C  (54°F)  with fewer waters. Allow the majority of the compost to dry out and provide a humidity tray while the radiators are operating. Most people will either discard or place the plant in the garden after flowering, due to the low chance of re-flowering. Read the following section for more information about what to do once the blooms finally elapse.




Dormancy Care & Annual Flowers

Trying to re-flower a Primrose isn't the easiest of tasks, but those that have a cool room without artificial light at night will be on the upper-hand. Repotting isn't usually mandatory if you want it to re-bloom - in fact, this may hurt the chances. Only repot every two to three years and after the blooming has finished. To get it to flower in the winter or spring months, think back to its previous dormancy period served in the summer. The following steps should be done at the end of spring, when Primroses enter their dormancy.

N. B. - Most people will discard or plant the Primrose in the garden once the flowers have elapsed - this method is great for those who want to keep it, but can't provide specialist care over the next year.

Light

Be sure to provide a bright location with little direct light over the course of the year. Although the sun won't necessarily hurt the plant, you can easily fall in the trap of under-watering, potentially weakening it. In order for the Primrose to fully become seasoned, avoid the use of artificial lighting during the nights.

Hydration

Reduce irrigations so that the majority of the soil becomes dry. Remember, they should only be watered from the bottom-up as rotting foliage are a common issue with cooler temperatures.

Occasional Feeds

While it's bloom, you won't need to feed them. During the dormancy period, only supplement once or twice to carry it through until the following spring, using a general houseplant fertiliser. 

Reduce Everything

This one is to remind you that everything needs to be reduced - especially the temperature.

Temperature

This is the most significant step - keep the temperature around 15℃  (59℉)  throughout summer, until buds form in mid winter. It'll be highly unlikely for Primroses to sufficiently bloom when the ambient temperatures are kept the same all year around, so we can't empathise the importance of this step!

Pink varieties are among the most popular across Europe, with others being white, purple and orange.

Origins

Primula is a perennial genus consisting of over five hundred species and a hundred more cultivars. They originate largely from the Himalayas, but can be found in temperate locations in central Africa, and South America. The genus was first described back in the 1750's by Carl Linnaeus, using the Latin word for 'prime', in reference to their flowers being the first to show in spring.


Temperature

3° - 22°C   (37° - 72°F)
H1c - Primroses can be place outside once the risk of frost has elapsed, or kept indoors all year round.  Plant them in a semi-shaded location in the garden, away from potential standing water or persistent droughts. 


Spread

Up to 0.3m in height and 0.4m in width. The ultimate height will take between 4 - 6 years to achieve.


Pruning

Remove yellowed or dying leaves and plant debris to encourage better growth and improve the all-round appearance. Pruning must be done with clean scissors or shears to reduce the chance of bacterial and fungal diseases; remember to make clean incisions as too much damage can shock the plant.


Propagation

Via seed or offset division. To learn about the essentials with sowing seeds, be sure to click on this link - Seed Propagation Tips.

For the latter method, take division cuttings once the new growth appears in springtime. Divide the rootstock into several sections, all with at least one growth bud attached. While the plantlet is still young, avoid direct sunlight and water-logging - use a well-draining potting mix like multi-purpose compost for the best chance of survival.


Flowers

Primroses are a tender perennial, meaning that as long as the temperature doesn't dip below 5°C, it should re-flower in the following winter or early spring. Each flower can last up to ten days, with the overall show lasting three weeks. Always avoid misting or saturating the petals, as you'll run the risk of developing botrytis petal blight. 


Repotting

Repot every three years in the spring using Houseplant compost with added perlite or grit, whilst the plant isn't in bloom. For matured specimens, introduce more grit to promote a stronger root ball as well as the reduction of potential root rot; click on this link for more information on how to perform the perfect transplant.


Diseases & Pests

Common diseases with Primroses are root or crown rot, leaf-spot disease and powdery mildew. Keep an eye out for spider mite, thrips, aphids & mealybugs. For more info on how to address any of these issues, hit this link.  Identifying Common Houseplant Pests & Diseases


Toxicity

Considered poisonous by consumption of pets and humans. If high quantities are eaten, it may result in vomiting, nausea and a loss of appetite.


Retail Locations

Some florists & Online Stores. Specimens are likely to be found in winter or spring inside at most garden centres; it's not advised to bring outdoor plants inside as this could lead to environmental shock with the risk of introducing pests into the home.

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