6o 
THE NATIONAL NURSERYMAN 
HOW TO FORCE LILACS 
By B. B. C. FELIX of FELIX & DYKHUIS, Boskoop 
One of the most popular shrubs for forcing is the Lilac. 
Their large trusses of fragrant flowers are universally ad¬ 
mired and the erect way they carry their blooms gives them 
a stateliness of form and noble appearance which is not 
easily rivalled. 
Before a Lilac can be forced into bloom it wants a period 
of rest. The plants when grown in pots go into a dormant 
state about the latter part of October. A well grown Lilac 
differs from a poorly grown one hot always by its larger num¬ 
ber or thickness of its branches. Both plants may look 
almost alike. Sometimes the shape and appearance are in 
favor of the badly grown one. The chief value lies in the 
way they are treated during the summer. They should be 
grown in such a way that they go into the dormant state 
early and yet have stored sufficient nourishment to feed a 
full sized flower. It is easy to grow a nice looking Lilac 
but hard to grow an easy flowering one. If the roots are 
allowed to grow over the pots they make a strong growth 
and a field of Lilacs grown in this way looks very healthy 
and flne as a rule, but their value for forcing is very doubtful. 
When the Lilac plant goes into a dormant state in October 
nature has not yet fulfllled its task. Although the super¬ 
ficial observer sees nothing uncommon on the buds, inside 
of them there goes on a number of chemical processes that 
makes them ready for the coming spring. Not before the 
buds are fully prepared can a full sized flower be produced. 
In winter with its frost and snow, when all trees look 
apparently dead or asleep, nature continues to care for her 
children and prepares and develops them to objects of 
beauty which are admired by all of us. This secret, hidden 
process is of a great importance for the coming flower and 
must be considered when we think of anticipating the rules 
of nature. 
Before the plants should be forced into flower it is neces¬ 
sary that the period of rest is sufficiently advanced. That’s 
why a plant forced in January or February forces easier 
and gives better results than when forced in December. 
To shorten this period of rest, freezing, hot water-treat¬ 
ment and aetherizing are applied with good results. Plants 
that have been exposed to frost have their period of rest 
shortened. For this reason it is advisable to heel the plants 
in outside so they are exposed to frost. 
Hot water treatment is best applied in a basin of water 
of 85 to 95° Fahr. Only the buds and shoots need to be 
treated, the rootballs are left out. This treatment takes 
about 6 to 10 hours. If the temperature of the water is 
lower (70-80° Fahr.) 10 to 12 hours will be neccessary. 
Plants that have been exposed to frost need shorter treat¬ 
ment. 
Etherizing is done in an airtight box in which aether is 
placed and vaporized. This treatment takes about 24 hours. 
Although it is rather difficult to give definite rules for 
forcing Lilacs we shall try to explain in the following lines 
the most essential. It must, for the greatest part, be left 
to the forcer to understand the exact needs of the plant 
and its requirements as to watering, airing and heating. 
We shall also explain how to insure Charles Dix its delicate 
lilac color, which is something unknown to the majority of 
Lilac forcers. 
Lilacs can be had in bloom at Christmas but the success 
with them is not very sure when they are not previously 
exposed to one of the three ways to shorten its rest period. 
We would therefore advise not to bring more plants inside 
than is necessary, for the results are uncertain. The later 
the plants are brought inside the better. They force easier 
and make better flowers and trusses. 
Lilacs need a high temperature and the idea of letting 
them come slow, or as some florists sometimes say “almost 
natural’’ is entirely wrong. They should be forced. The 
meaning of that word clearly expresses itself. To let them 
come slow is not forcing and the results are not the same 
as what can be expected of forced plants. When Lilacs 
flower outdoors they do not make the large trusses and 
flowers as when properly forced. 
When the Lilacs are taken into the hothouse they should 
at once be given at least 80 to 90° Fahr. If it is not possible 
to give them as much heat from the greenhouse pipes and 
if there are other plants in the same house that do not 
require as much heat we would advise the placing of the' 
Lilacs in one end of the house and having this part separated 
from the other part with boards, glass or canvas. Then to 
bring the heat of the division to the necessary temperature 
is it advisable to place a stove inside and on top of this a 
vessel of water. The heat of a stove is very favorable to 
lilac forcing. It makes the air dry where the boilers make 
it damp. Stove heat is very desirable. One has to spray 
abundantly 3 or 4 times a day through the branches and 
buds and also to have the rootballs in the pots sufficiently 
wet. On account of this spraying the surface of the soil 
will look rather wet,-but this is deceptive; for the lower parts 
of the balls are sometimes too dry. On the other hand the 
balls should not be too wet. The plants do not consume 
much water in the first 8 days and if too wet the roots will 
get rotten. Here it is where the forcer should use his own 
judgment a great deal. He should know how much or how 
little to give. The buds have to be constantly kept moist. 
Within 10 to 12 days the buds break open and are about 
a finger in length. This is the time to lessen the heat until 
the trusses have attained their full size, which takes about 
2^^. weeks. The spraying should methodically be lessened 
at this time. When the flowers begin to expand, a very 
thin spray once or twice a day will be sufficient. If the 
flowers are open the spraying should be stopped. Spraying 
on the open trusses is ruinous to the blooms. 
The last 8 to 10 days the Lilacs can get sufficient heat 
from the greenhouse pipes and it is only with dark, wet 
weather that the stove needs to be used. During forcing it 
is well to give them a little airing once in a while. 
