Top of The Crops - Borage

Growing Borage In A Polytunnel

Borage is a sturdy, annual plant that will readily self-seed and return year after year if you allow it to do so. 

While borage will generally also grow outside in the UK climate, it may be a valuable addition to the polytunnel as it is said to be beneficial as a companion crop to a range of edible plants that you may be growing. 

Borage itself also has edible flowers, which resemble cucumber and could be perfect topping for a summer pudding or cocktail.

Key Information

Borage has many uses in a garden. It can be used:

  • As a companion plant for most common annual kitchen garden crops. 

  • And as a 'living mulch' which can be chopped and dropped, or harvested and used for household purposes or fertility in the garden. 

  • Or as a self-seeder in forest garden or perennial vegetable garden design – especially prized in such schemes for its nectar production and benefits to local wildlife. 

  • In herb gardens, alongside a range of other culinary and medicinal herbs. 

  • In an informal annual flower bed or wildflower meadow area. 

What is Borage?

Borage is the name given to Borago officinalis and certain other related plants. Borago officinalis is usually the plant referred to. It is an annual herbaceous plant native to the Mediterranean region but now cultivated worldwide, which is known for its vibrant blue, star-shaped flowers and hairy, rough-textured leaves. 

Borage is commonly grown in gardens both for its ornamental value and its culinary and medicinal uses.

Choosing Borage for Your Garden

When selecting borage for your garden, consider the following factors:


The most commonly seen borage variety (Borago officinalis) features blue flowers and is typically grown from seed.

However, you can also find young plants available in spring and early summer. Additionally, there are variations such as Borago officinalis 'Alba', which boasts pure white blooms, and B. officinalis 'Bill Archer', characterized by cream variegated leaves.

Eventual Size

It's important to anticipate the eventual size of borage plants to ensure they have enough space to thrive in your garden. 

Borage (Borago officinalis) typically reaches heights of 50-70cm (20-28in) and presents as a handsome, erect plant. However, if the soil is dry or poor, the plants may be shorter. Seedlings germinated later in summer tend to flower but will also be shorter compared to those germinated in spring. 

A shorter, related option is  B. pygmaea - a hardy perennial option. This variety only grows to about 30cm (1ft) tall and has a creeping habit.

Buying Borage

Borage plants are widely accessible, with garden centres, plant nurseries, and online suppliers offering a variety of options. You can typically purchase seeds, but young plants are also sometimes available. 

Where to Plant

This plant exhibits remarkable adaptability to various growing conditions. It thrives in a wide range of soil types, even those with low nutritional value. Additionally, it can tolerate different soil pH levels, including highly alkaline ones. Its resilience extends to free-draining soils, and it demonstrates notable drought tolerance. Whether in full sun, light, or dappled shade, this plant flourishes.

Where to Grow Borage

You are free then, to think about where borage might usefully be grown in your garden. As mentioned earlier in this guide, borage is a very useful plant that can be used in a wide range of different garden schemes and as you will discover later in this guide, borage can benefit many other species when grown close by. 

When to Plant

Borage is very easy to grow from seed. It can be sown indoors around a month before the last frost date in your area or direct sown as soon as risk of frost has passed where you live. Though you can also choose to purchase plants and plant these into your garden. 

How to Plant 

In the Ground

Planting young borage plants in the garden is a straightforward process. You only need to dig a hole of sufficient size to accommodate the roots, then gently firm the surrounding soil and water the plant. While it's not necessary to amend the soil with organic matter, doing so can enhance the growth of your plants. It's recommended to space the plants approximately 50cm (20in) apart for optimal growth.

In Containers

Transplant borage by placing it in a multi-purpose peat-free compost. Alternatively, you can sow seeds directly onto the compost surface in spring (see Propagation below). You can fit one borage plant into a 30cm pot.


Borage will bloom over a long period in the summer and flowers can simply be pinched off as and when they are required. You may also wish to harvest leaves sparingly as and when these are required. 

Edible and Medicinal Uses of Borage

In culinary applications, borage leaves and flowers are often used as a garnish in salads or drinks due to their cucumber-like flavour. The flowers are also edible and can be candied or used to decorate desserts. Additionally, borage leaves can be cooked as a vegetable or used to flavour soups and stews.

In traditional medicine, borage has been used for its purported medicinal properties. It is believed to have anti-inflammatory, diuretic, and expectorant effects, among others. Borage oil, extracted from the seeds, is rich in gamma-linolenic acid (GLA), an omega-6 fatty acid with potential health benefits.

Borage Companion Planting

Borage can bring benefits to a range of other plant species when grown close by. It is one of the best companion plants to choose for a number of garden settings and situations because it:

  • Is low maintenance and self-seeds readily in the right conditions, meaning that although it is an annual it can work well amid perennial plants and can return to your garden each year. 

  • Borage roots help to break up and aerate the soil, reducing compaction, and the plants can protect soil by helping to keep it covered. 

  • Borage is a great nectary plant – attracting bees and other pollinators. 

  • It also attracts aphids, serving as a trap crop, and attracting beneficial predatory insects. 

  • Borage is a 'dynamic accumulator' meaning that is is particularly good at gathering certain nutrients – mainly potassium in this case. So it can be chopped and dropped, used as mulch, added to a compost heap or used in an organic liquid plant feed to provide this nutrient and others to other plants. 

Care Tips for Borage 

Borage is very easy to grow which is one of the reasons why it is so beneficial to grow it in an organic garden in the UK. However, like any other plant is does need some consideration and care if you want it to grow successfully. 


Watering needs will differ for borage depending on whether you are growing in the ground or in containers. 

In the Ground

In the ground borage does not typically need to be watered at all as natural rainfall will be sufficient. Of course, if growing borage in a polytunnel, undercover, you will need to make sure that you keep the soil moist but not waterlogged throughout the growing season. 

In Containers

If you are growing borage in containers, you should also remember that you will need to water more frequently, even when these are positioned outside where they get watered by natural rainfall too. Make sure that you water through summer to make sure that the growing medium in your container or containers does not dry out. 


Borage does not usually require additional feeding or fertilizer as long as it is growing in a reasonably fertile soil, and it can cope well even in poor soil conditions. Though borage in pots may benefit from a balanced, slow-release organic fertilizer in spring. 


Borage thrives in both full sun and partial shade. However, cultivating borage in full sun maximises the chances of abundant blooms and sturdy stems.


Borage demonstrates resilience, thriving even in dry, nutrient-poor soils. However, it prefers moderately moist, well-drained soil. It exhibits tolerance to a wide pH range (4.5–8.5), with a preference for slightly acidic conditions. 

Enhancing your soil with organic matter like compost can provide your plants with a bit of a boost.

Temperature and Humidity

Borage is renowned for its hardiness, capable of enduring a wide range of temperatures. While it can withstand both heat and cool weather, it is susceptible to damage from hard frosts. It is unfussy when it comes to humidity. 


Borage is an annual plant, meaning it completes its life cycle within one season, eliminating the need for overwintering considerations. Due to its prolific self-seeding nature, it's advisable to remove the plants from the ground at the end of the season if you wish to avoid numerous volunteer plants. Additionally, borage decomposes readily, making it an excellent addition to compost heaps.

Caring for Old Plants

Since borage self-seeds abundantly, consider removing the plants from the ground to prevent the spread of volunteer plants in unwanted areas of your garden. You can compost the removed plants or use them as mulch.

But where self-seeding is beneficial, simply leave the plants to die back naturally at the end of their lifecycle, and let the seeds fall where they may so that you may get plenty of borage seedlings popping up close by the following year. 

Pruning and Training

Remember that common borage is annual and will not live into a second season. But to manage perennial B. pygmaea at the end of the growing season, tidy up by cutting it down in autumn. This pruning will facilitate healthy regrowth in spring, ensuring the plant's vigour for the next growing season.


Borage is usually propagated by seed, either seed that you purchase or collect, or that produced by borage plants already in your garden. 

It is usually also possible to successfully divide perennial borage, Borago pygmaea, once it reaches a good plant size, preferably in the early spring.

Growing from seed

Remember, borage self-seeds readily. But sowing seeds is also usually the easiest method to obtain new borage plants for a garden. Seeds can be sown in April indoors or after the last frost date in your area outside, directly where they are to grow.


While borage plants are generally resistant to pests, they can be susceptible to powdery mildew, particularly later in the summer when flowering is nearing its end. If your borage plants show signs of powdery mildew, such as a white powdery substance on the leaves and stems, it's best to remove these affected plants. Simply pull them up and dispose of them to prevent the spread of the disease to other plants in the area.

Varieties of Borage 

Varieties of borage for UK growers to consider include:

  • Borago officinalis: This is the common variety of borage with bright blue flowers and a cucumber-like flavour. It's widely grown for culinary and medicinal purposes.

  • Borago officinalis 'Alba': This variety produces white flowers instead of the typical blue ones. It offers the same culinary and medicinal benefits as the standard borage.

  • Borago officinalis 'Variegata': Known for its variegated foliage, this borage variety adds visual interest to gardens. It still produces the characteristic blue flowers and is suitable for culinary and medicinal use.

  • Borago officinalis 'Bianca': Another white-flowered variety, 'Bianca' offers a striking contrast to traditional blue borage. It retains the same flavor and medicinal properties.

  • Borago officinalis 'Gold Trim': This variety features gold-edged leaves, adding a unique touch to the garden. It produces blue flowers and is suitable for culinary and ornamental purposes.

  • Borago pygmaea, also known as Alpine Borage or Pygmy Borage. This species is smaller in size compared to common borage and tends to be more compact, making it suitable for smaller gardens or containers. It produces blue, star-shaped flowers and is known for its perennial nature, regrowing each year without needing to be replanted.

  • Borago longifolia, commonly known as Longleaf Borage or Narrowleaf Borage. This species has elongated leaves compared to common borage and tends to be more cold-hardy, making it suitable for cooler climates. It also produces blue flowers and can self-seed to some extent, allowing it to persist as a perennial in the garden.

Top Tips for Growing Borage in a Polytunnel 

Borage should thrive in a polytunnel as it likes a sheltered location out of strong winds that can knock it over. Generally, however, borage will do well anywhere, as it is not fussy when it comes to soil type or conditions.


Does borage come back year after year?
Where is the best place to plant borage?
Is borage good for your garden?
Can you grow borage in pots?


Ajmera, R., (2020) What Is Borage? All You Need To Know. Healthline. [online] Available at: 

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growing borage in a polytunnel