Lime trees / basswood or Tilia species
I have always associated lime trees with summer. In the southern part of the Netherlands where I live, the town council has planted many trees and if the conditions are right, especially on warm and humid days, the fragrance of tilia in flower is overwhelming.
I happen to have a garden which at the end does not border any other garden and I have been very bold to plant a tilia cordata or small-leaved lime. When it becomes too tall it can be cut back hard and repeatedly. The tree has always been used for coppicing and our ancestors have found a use for all parts of the tree: the leaves were used to feed cattle, the flowers helped against colds and the fibers of its bark were also used.
Many trees have been planted on acidic soils as they were not suited for agriculture. The trees planted there were mainly conifers, oak and beech. All of them known to further enhance the soil acidification. In this type of soil many of the beautiful spring plants such as lily of the valley, wood anemone are no longer found. When planting Tilia cordata, researchers discovered that the process of acidification was altered: its dense root system enabled the lime tree to take up nutritions from deep down the soil, in particular calcium. Its leaves contain many minerals and in autumn when they fall, they are favoured by earth worms. Whereas it may take up to two years for a beech leaf to decompose, a leaf of a lime tree is usually dealt with in a few months time. The leaves feed the soil organisms and are eventually broken down into a rich mull humus. The upper soil years after the lime trees were planted contained more calcium and other minerals and spring flowers returned.
In many gardens it is impossible to plant these trees but there are good alternatives. Although natives are often preferred as they are the food plants of several species of moth caterpillars, the non natives are also valuable as they provide nectar and pollen for all kinds of pollinators. I also think we have to be less rigid when it comes to planting non natives: after all, we all have lavenders and butterfly bushes in our gardens, both not native.
I am growing Henry’s Lime, Tilia henryana with the most amazing large leaves. It grows best in a somewhat sheltered position but it survived -19ºC during last winter. It flowers very late in August-September which is very important as few plants are still in flower during that period. It is said that its fragrance can be noticed up to 100 metres from where the tree grows. When the leaves emerge, they have a beautiful colour which you can see from the picture below.
Please note following: For lime trees to produce enough nectar the soil needs to contain moisture. Otherwise they may smell great but due to the dry conditions the flowers will produce not much nectar.
Two order options for the smaller gardens are Tilia Japonica Ernest Wilson, previously known as Tilia insularis. This tree grows to about 10-15 metres and its leaves are similar to the small leaved lime. The leaves have a very soft texture, which are shaped like a heart with a bit of imagination. With the right conditions, this lime tree turns bright yellow in autumn and is a very rich flowering tree.
The other tree I grow is Tilia kiusiana also from Japan. This tree can grow more like a shrub but grows slowly. It it said to grow to about 8 metres maximum but this depends so much on other factors such as soil fertility, sunny position, moisture etc. The fragrance of this tree in flower is also very appealing and popular with all kinds of bees.