Sunflower grow diary: 14 weeks to print

In short: sow a sunflower seed in May, put it in the sun and give it water. Each week, on the same day, measure the height and write it down in the table below. After about 14 weeks it flowers — and you can see how much it has grown!

First, sow

Before you can measure, something has to grow first, of course. Sowing goes like this:

Wait until there is no more frost at night. In the UK and the Netherlands that is around mid-May. Not sure about the date? Have a look at the sowing calendar.
Push a sunflower seed about 2 centimetres deep into the ground or into a big pot of potting compost.
Give it a little water straight away, so the soil is moist.
Put the pot in the sunniest spot you have — a sunflower loves lots of sun.
Give it water as soon as the soil feels dry. After about a week the little plant comes up.

Which variety do you choose? Want one taller than mum or dad? Then pick a tall variety. Want a small one for the balcony? Have a look at the choices under species.

How do you measure well?

Tips for measuring fairly

Measure each week on the same day, for example every Sunday. Then you can compare properly.
Measure from the ground to the highest tip of the plant, with a tape measure or ruler.
Write the height down in centimetres (cm).
Count the leaves too and write down the number. Don't count the very smallest leaves at the top if they are still folded up.

The grow diary (14 weeks)

Fill in one row each week. Under "drawing or photo" you may do a little drawing or stick in a small photo.

My sunflower is called: ______________________ · Variety: ______________________ · Sown on: ____________
Week	Date	Height (cm)	Number of leaves	Note	Drawing or photo
1
2
3
4
5
6
7
8
9
10
11
12
13
14

What do you see happen?

In the first weeks your plant grows slowly. Then, somewhere around week 4 to 8, it suddenly shoots up — sometimes as much as 10 centimetres a week! After that a bud appears, and it opens into a real flower. Compare your numbers: in which week did it grow the fastest? Try turning your heights into a graph with one dash per week; then you can see the growth as a line going up.

Questions to think about

In which week did your sunflower grow taller the fastest?
How many cm did it grow in total from week 1 to week 14?
Which way does the flower head face? (Do the experiment about heliotropism as well.)
How many seeds do you think there will be in the middle later on?

For teachers and parents

The grow diary links nature education (life cycle, growth) with maths (measuring in cm, counting, filling in a table and perhaps making a graph) over a period of 14 weeks — a lovely long-running task for the summer season. Have pupils measure on fixed days, so the data is comparable, and discuss the growth curve: a slow start, a rapid growth spurt, then a levelling off at flowering. Combine it with the experiments and with practical growing information and sources on the growing page and the sowing calendar. If you like, print several copies or let each class adopt one plant.

Tip: take a photo in the same spot every week, with your child next to it as a "measuring stick". At the end of summer you can lay all the photos side by side — a strong, motivating picture of how much the plant (and your child) has grown.