Plant Advice
A helpful guide to three of our most-loved plants, including how to grow them well at home.
Agapanthus
When your plants arrive home – water if necessary, leaving them to settle for a couple of days. We recommend 9cm pots are potted up before planting outside. Larger Agapanthus may be planted in borders or potted into larger containers. We do not recommend planting if the weather is frosty.
Planting in the Garden – Agapanthus thrive in well-drained soil, in a sunny site that receives sun for most of the day. In heavy soils, mix in grit when planting to improve drainage, otherwise follow the instructions on the reverse of the label. Dwarf plants can be planted 30cm apart and larger forms 60cm.
Hardiness – Agapanthus have fleshy roots and leaves which can make them prone to frost damage. The hardiest of Agapanthus are deciduous, dying down in winter. Deciduous types will survive most UK conditions once they are established in flowerbeds, but should be protected from temperatures below -5ºC during their first winter or two. Low temperatures will have a greater impact on deciduous plants that have been planted in soil that is badly drained. Deciduous plants in containers are prone to root damage in freezing temperatures so should be moved to a green house or under the eaves of a house to ensure roots don’t freeze especially after rain.
Evergreen types are more tender and their leaves can be easily damaged by frosts. Therefore, plants should be moved into frost free locations in cold areas. In milder areas a mulch of straw or fleece is advisable when plants are establishing or temperatures below -5ºC is forecast.
Established clumps of evergreen Agapanthus can withstand short periods of up to -10ºC if the ground is well drained, but the number of flowers maybe reduced the following summer. Planting in beds against house walls can reduce the likeliness of frost damage.
We do not recommend planting 9cm pots into the ground directly as they will be more prone to frost damage.
Feeding – Agapanthus are quite hungry feeders. For best results apply a top dressing of our Agapanthus Plant Food to the surface of the soil. It is best applied first in March, then repeated in May and August. Alternatively, liquid feed plants in containers with Phostrogen liquid feed during the growing season or tomato feed which contains high levels of Potash. A sprinkle of Sulphate of potash can also encourage flower quantity and colour. Avoid giving plants too much Nitrogen or you will encourage lush leaves at the expense of flowers.
Pruning – Flower stems should be cut down after flowering, unless you wish to
leave them for winter structure in the garden, or spray them silver or gold once dried as Christmas decorations.
Dividing and encouraging flowering – Plants that don’t flower or are over-crowded may be divided in late summer after flowering or in early spring. Large plants maybe pulled apart using 2 forks after lifting from the ground or removing from the pot. Agapanthus doesn’t like to be re-potted into pots that are too spacious as this will encourage leaf growth rather than flower production. Ideal conditions are provided where root development is restricted but the plants are well watered and fed through the growing season. The belief that flower production is maximised when the roots are climbing out of the pot is not correct.
Why won’t my Agapanthus flower? – It is a myth that Agapanthus must be grown with their roots heavily congested-they love water and are hungry feeders so with no soil in the pot it’s hard to give this to them. If your plant is flowering do nothing! If not-
- Give it maximum sun
- Feed it high potash fertiliser such as Fairweather’s Agapanthus feed
- If it is evergreen ensure that it does not get frosted in winter – buds are formed in the autumn
- Divide if it is over congested
- Buy a new one!
Lavender
When your mail order plants arrive – unpack and water if necessary, leaving them to settle for a couple of days. We recommend 9cm pots are potted up before planting outside. We do not recommend planting if the weather is frosty.
Soil and Site - We are always asked how to grow lavenders. Lavenders like well-drained soil in a sunny site that receives sun for most of the day. Lavandula angustifolia prefers alkaline soil which will help extend its life whilst Lavandula stoechas subsp. stoechas and to a lesser extent Lavandula x intermedia, can thrive in slightly acid soil. Lime maybe added to acid soils where necessary.
In heavy soil, mix in grit when planting to improve drainage and plant on a slight mound. Wet soil in winter can have a terrible effect on half-hardy and frost hardy lavenders and it is wet soil, rather than frost that is more likely to kill these plants.
Spacing - Lavender angustifolias and x intermedias make excellent hedges. Plants should be spaced at 40cm for angustifolias and 45cm for x intermedias. For planting in borders we would suggest groups of 3 planted 60cm apart.
Planting and Watering - Follow the instructions on the reverse of the colour label when planting your Lavender. If your soil is not free draining add 1/3 of Horticultural grit by volume to the soil. Be careful not to overwater plants in dry periods as Lavenders prefer to be on the dry side rather than waterlogged. Avoid watering the foliage wherever possible and try to water in the morning so that the foliage can dry before night time. Established Lavenders do not need watering even in droughts.
Plants, especially stoechas subp, stoechas types lend themselves to being grown in pots as plants maybe be given some winter protection from wet and cold by moving under cover. Keep plants in pots dry throughout the autumn and winter.
Hardiness - Lavandula angustifolia and x intermedia are hardy in most of the UK and can withstand up to -15ºC. Most losses overwinter are due to the lack of drainage rather than cold. Lavandula stoechas subsp. stoechas are less hardy and will survive some frost- to between -5ºC and -10ºC, but as with angustifolias are more likely to be killed by wet and frozen roots. Therefore, the more free draining your soil the better the chance of winter survival.
Feeding - Lavenders are not hungry feeders so avoid giving them manure or Nitrogen based fertilisers. A sprinkle of Sulphate of potash or watering with Tomorite can encourage flower quantity and colour.
Pruning - Lavender angustifolia and x intermedia Prune immediately after flowering, cutting the flower stalk back hard into foliage below its base- 20-30cm above the soil. Make sure you leave 3 pairs of leaves below your cut as this is where the re-growth will emerge from. If you cut into bare wood you may get no re-growth.
Lavender stoechas subsp. stoechas -These tend to flower most in late spring and then repeat flower through the summer. You have to sacrifice some flowers in order to keep your plants in shape and this is best done after the main spring flowering. Cut back into the stems 20-30cm above the soil, ensuring you leave at least 3 sets of leaves below your cut. Continue deadheading over the summer and into autumn and a light prune in August may also provide additional shape before the winter.
Heuchera
When your mail order plants arrive – unpack and water if necessary, leaving them to settle for a couple of days. We recommend 9cm pots are potted up before planting outside. We do not recommend planting if the weather is frosty.
Planting in the garden – Heucheras are happy in most soils, provided that they have good drainage. They do well from mulch to keep the soil structure open. When planting, avoid other plants hanging over them, as they do like lots of air around them.
Hardiness – Heucheras are hardy, they do not require fleece to keep them warm and alive.
Growing in pots – Plants with smaller leaves are suitable for smaller pots, containers, window boxes or even a hanging basket. The larger leaved plants are better in larger containers. If going away in the summer, move the pot to a shaded area, it will reduce the need for water.
Feeding – They are not heavy feeders and need little fertiliser to grow well. The combination of mulching and some fish, blood and bone in spring, will provide them ith all the nutrients they need. Avoid nitrogen rich fertilisers as this will encourage fleshy foliage which is prone to rotting.
Pruning – Most Heucheras produce flowers in late spring/early summer. To help prolong the flowering period and to stop them from getting leggy, snip off the flower stems just below the foliage level when the flowers die. In spring clean your plants by removing dead or damaged foliage.
Dividing and encouraging flowering – After 3 or 4 years they may probably start to look bedraggled and the foliage won’t be so proud and upright. This is time to divide it and grow as many new plants as you need. Late May to early July is a good time to do this.
Heuchera Rust – Heuchera Rust can be identified by small rust coloured raised areas on the underside of leaves. To prevent rust remove any leaves in bad condition or ones that are old, clear-up decaying matter around the plants and don’t crowd them with other plants.
If you do find rust on your plants and it is minor we would suggest removing all infected leaves and spraying with a fungicide.
Vine Weevil – Heuchera foliage is not often attacked, this could be because the leaves are hairy. However, they will attack the roots. You will know as the plants will wilt as though they need water. Heucheras are pretty tough and once cleaned of these bugs and re-potted they should continue to strive.