Lavender types not only differ in size, flowering and scent, but also in whether they are hardy. If you don’t want to overwinter the plants indoors or plant new plants every year, you should be careful when choosing. Because only hardy lavender can be outdoors all year round. Even then, however, appropriate winter protection can be useful.
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Differences in lavender varieties
Blue, purple, white – even the color of the flowers is by no means the same for every lavender. The same applies to scent, growth height and width and whether the plant is hardy in the local latitudes. Only real lavender, which is called Lavandula angustifolia in botanical jargon, is really hardy. But even it can only tolerate minus 15°C without being damaged. In milder regions, it can therefore be left outdoors all year round without any problems. In regions with harsher winters, however, it should at least be protected.
Which lavender varieties are hardy?
Depending on the region and the temperatures prevailing there, the right types of lavender should be selected. But which species are suitable for which temperatures?
- up to -15 ° C: True lavender (Lavandula angustifolia)
- down to -10°C: French lavender, French lavender, Silverleaf lavender and woolly lavender withstand these temperatures
- not hardy: spike lavender and fern-leaved lavender
If you want to leave the plants outdoors all year round and do not want to apply any special winter protection, it is best to use Lavandula angustifolia. All other varieties are only suitable if at least protection can be provided by means of pads on the ground or another cover.
Harden lavender varieties
If the plants are to be outdoors all year round and not hibernate indoors, three steps should be followed. These are:
- Plant outdoors as early as possible in spring. This gives the plants enough time to get used to the rising and falling temperatures.
2. Plant in a sunny but sheltered location, because the plants do not tolerate winter sun well.
3. Protect from winter sun and winter drought if necessary by using a cover on the ground and on the lavender. Brushwood, straw and mulch prevent the soil from drying out and provide at least some protection against ground frost. A fleece over the plant prevents the leaves from burning in the winter sun or the crop from drying out.
Overwinter in the bucket culture
It doesn’t matter which lavender variety it is – when cultivating in tubs, a few points must be observed for overwintering. These are:
- Frost-free: The plants do not have enough substrate volume in the tub to be adequately protected from the sub-zero temperatures. Therefore, wintering must always be frost-free. This can either happen in the house or the plant is protected from the sub-zero temperatures with several layers of garden fleece and a pad made of styrofoam.
- bright: Full sun locations are unfavorable for the plants – at least in winter. Because then not enough moisture can be absorbed from the soil, but a lot of liquid is released through the leaves. Therefore, bright rooms or locations that are protected from the blazing midday sun are better.
- Prevent from drying out: Whether in the garden or in a bright, frost-free hallway – the plants should not dry out during the winter. The lighter and warmer the lavender is, the more water it needs. Growth is then restricted, but the plant still uses water through evaporation. Therefore, it should not dry out under any circumstances. It makes sense to water outdoors on frost-free days and to water sparingly about once a week during the winter indoors. It is important that the substrate never dries out completely, as this can result in consequential damage.
Winter protection outdoors
If the lavender plant is to remain outdoors during the winter, appropriate protection is also required for the more robust varieties. The following measures can help ensure this:
- Sheltered Location: Sunny and sheltered but no unobstructed winter sun and no cold wind
- Put them outdoors early: the sooner the better. Then they are hardened and show themselves to be more robust against cold temperatures.
- Tub culture: Overwintering in tub culture is easy, safe and requires little effort. In regions with cold winters or when it is unclear whether the respective lavender variety is suitable for the region, pot culture should therefore be preferred.
- adapted care: the better the care, the stronger and more resistant the plant.