21/07/2019
Lavender Care
Soil
Lavender plants and rosemary plants require well-drained neutral to alkaline soil, although Lavandula stoechas subsp. stoechas (which always grows in acid soil in the wild) and to a lesser extent Lavandula x intermedia, can thrive in slightly acid soil. If your soil is naturally good for growing rhododendrons and heathers add lime to raise the pH. About a handful per square metre in early spring should be sufficient. 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.
Site
Plant lavender and rosemary in a sunny position or at least where they are in the sun for most of the day. Don‘t grow them under a leaf canopy. Many can be grown in pots (see below).
Spacing
For informal plantings we recommend 45cm-90cm (18in-36in) between plants, depending on their eventual size. Planting in groups of three is very effective. For hedging, lavenders to 60cm (24in) and rosemaries may be planted 40-45cm (15-18in) apart. For a formal lavender hedge use one type – the effect is stunning! Any of the angustifolia and x intermedia lavenders make a fine hedge as do all upright rosemaries.
Planting in the Garden
Ensure the soil and site are as described above. Moisten the plant compost, but do not waterlog. Dig a hole and add a dusting of bonemeal to the hole, and the soil removed from it, and mix in. Fill the hole with water and allow to drain away. Place the plant in the hole and fill to the level of the compost around the plant and firm in. In dry conditions water the soil around the plant, but do not over water. It‘s easier to add water than to dry out the soil! Be attentive in the first few weeks after planting, especially if the weather is dry.
Planting in Pots
Tender and half-hardy lavenders and dwarf lavender and rosemary are ideal for 30-40cm (12-15in) terracotta pots and look particularly impressive on the patio. Use a mix of one third each of soilless compost, John Innes No.2 or 3 and coarse grit. For feeding, pop in a plug or two of slow release fertilizer, which should last all season. Short plants are great for growing in pots, but watch out for the fibrous roots of all lavender stoechas species and cultivars and the vigorous root systems of all rosemaries. Both will need potting-on regulary.
Watering
This should be unnecessary after establishment, except plants in pots which need frequent watering during summer. See also Overwintering below.
Feeding
Little feeding is required, although a sprinkling of potash around the base of plants will encourage more prolific flowering and improved flower colour. Don‘t add bulky manure or high nitrogen feed as your lavenders in particular, will grow very sappy and flop open.
Harvesting
Most lavender for culinary use is harvested when in full coloured bud before the individual flowers open. They can be added to ingredients while fresh or can be dried first.
To use lavender for drying and pot-pourri, harvest just before full-bloom and hang upside down in bunches in a dry dark room.
Overwintering
Tender and half-hardy lavenders and frost hardy lavenders grown in pots should be given protection in light, airy conditions. These plants need very little water from November to February. Wait until the pot is noticeably lighter or even until plants start to wilt and then water only on top of the compost. Never water over the foliage in winter. These plants find still, moist air rather unpleasant!
Pruning
We field more enquiries on how to prune lavenders than on anything else, so some detail is required. It‘s very important task that demands a strong constitution, because generally the harder the lavenders are pruned, the longer they will last. They require different treatment according to hardiness (see below).
Hardy Lavenders
These normally flower just once, but may have a weak second flush after pruning. To keep them really under control don‘t be frightened to chop them back to just 22cm (9in) or about a third into the foliage immediately after flowering… they love it! It‘s particularly important to be severe with the x intermedia lavenders, even if you have to sacrifice some late flowers. If there‘s a good smattering of small shoots visible below where you cut they‘ll grow strongly even from old wood, but beware, no shoots means no plant next year as your lavender will die. The exception is Dutch lavender, such as Dutch Group, Fragrant Memories and Lullingstone Castle. These flower well into autumn so just remove the flower stems then and prune into the foliage when the sap’s up, usually in March. If pruned at the correct time, new growth should leave lavenders overwintering as lovely leafy hummocks. Expect hardy lavenders to last up to 20 years, half that on a heavy clay soil.
You can even try to save that old gnarledlavender that has an arm‘s length of bare wood topped with a mass of growth. Prune to within a hand‘s width of the bare wood to see if this encourages sprouting further down the plant. If it does sprout, then when you next prune do the same again, until you can‘t see the ground beneath the plant. Of course if it doesn‘t sprout after the first prune put it on the bonfire and enjoy it‘s last lingering smoky perfume…
