
HINTS 
FOR FORCING OF DUTCH BULBS 
and 
DESCRIPTIVE LIST OF 
TULIPS and DAFFODILS 
Published by 
GENERAL BULB GROWERS SOCIETY ® HAARLEM - HOLLAND 




Hints for Forcing 
Hyacinths, Tulips, Daffodils, Narcissi, Bulbous Irises, Crocus, Muscati: 
General Rules 
Hyacinths, Tulips, Daffodils and Narcissi. 
1. What to do when the bulbs arrive. 
Unpack the bulbs immediately upon arrival and plant them as soon 
as possible. Prepared Hyacinths, Daffodils, Narcissi and Tulips for ear- 
liest forcing should be planted first. The rest of the bulbs according to 
their earliness. 
If for some reason or other you cannot plant the bulbs at once, they 
should be stored as described below. This storing of the dry bulbs is 
also advisable, while you are busy planting. 
Cool storage is essential for all bulbs required for early flowering. Heat 
- before planting will result in delaying the flowering. 
The best spot for storing the bulbs is a dry, well-ventilated place; 
the temperature should be as close to 50°F as possible. For Hyacinths 
55 °F is best. 
The best temperature for storing Hyacinths for February flowering is 
60 to 65°F and these should not be planted until the middle of 
October. 
Hyacinths for later flowering can be planted still later and the tempe- 
rature for these can be 70 °F, but not higher. (See further under Hya- 
cinths, number 3, Late Forcing). 
Hyacinths, which are not planted immediately upon arrival should be 
spread out in trays. 
When unpacking the Tulips, Daffodils and Narciss, take one or two 
out of the centre of the case or bag and cut them in halves. When 
the bud inside the bulb is yellow, you may be sure that the bulbs are 
in good condition. If on the other hand, the bud is brownish or brown, 
the bulbs — certainly those packed in the middle of the case — have 
suffered from heat and are therefore unfit for planting. 
2. Planting. 
The best soil for bulbs is a well-drained sandy loam and it should be 
fresh soil. Never use soil direct out of your greenhouse benches, nor soil 
ever used for growing bulbs before. This counts expecially for tulips. 
Never use soil containing fresh manure and don’t cover the planted 
bulbs with fresh manure. It can be very harmful indeed for the deve- 
lopment of the rootsystem. 
If your soil is very poor, it is considered safe to add a little bone 
meal or some phosphate to it. 
When planting the bulbs the soil should be real moist and cool. 
New pots or pans should never be used, unless they are thoroughly 
soaked in a water tank for, if possible, four weeks, to avoid burning 
of the roots. It is obvious that all receptables used, must have proper 
drainholes. When boxes are used, wide splits in the bottom for drainage 
are necessary. Flats and boxes should be deep enough to let the bulbs 
root freely. The top of the bulb, however, should be just above the 
rim of the flat or box. 
If possible, flats or boxes for Daffodils and Narcissi should be 1 to 
2 in. deeper than those used for Tulips. 
3. Trenching or placing in rooting beds outdoors. 
It is most important to place the planted bulbs where it is ¢oo/, not 
too dry and well drained. 
Take by preference a shady part of the grounds with a soil tempe- 
rature between 48 and 50 °F. If warmer the growth will be delayed 
and if real cold it wiil cause a standstill. 
Heat is detrimental. A place covered before with salt hay or straw to 
keep the summerheat out, will suit very well. 
lf the place for the rooting beds is too dry; soak it first and fork it 
well, keeping the soil loose. 
The pots etc. should be covered first with 1 to 2 in. clean sand or 
grit, and next a layer of covering soil from 6 to 12 in. depending on 
the climate. The first layer prevents damage to the sprouts, when, 
during frost, the last layer has to be taken away before bringing the 
pots into the greenhouse. 
In districts where severe winter frosts are prevalent, it is necessary 
to cover the top of the rooting beds with a layer of salt hay of straw 
(on no account fresh manure !). If using straw, watch out for mice and 
rats. They can damage your bulb pit tremendously. 
Spray the rooting-beds with cold water and repeat this once or 
twice a week during warm periods. Drainage must be good, make a 
trench alongside to carry off excess water, 
lf in your district winter in this period is so severe that you will be 
unable to get at the bulbs buried outdoors, the ideal way to store 
them is in a cellar. - 
