Step 5: Keep a Kratky grow journal

Keep a grow journal

A Kratky grow journal is a simple record that helps you learn what works in your space.

Note your plant's progress each week: how tall it is, how many leaves it has and what the roots look like.

Give it light

Put the plant near a sunny window or under a grow light for most of the day.

What to record in your grow journal

• The date
• Plant height, from the lid to the top leaf
• Number of leaves
• Where the water level is
• What the roots look like (color, length, air roots and water roots)
• Anything new: a new leaf, a flower bud, a pest, a change in color

A photo from the same spot each week is a quick way to track growth over time.

Light is food for plants

Plants use light to make their own food through photosynthesis. Leafy plants need plenty of light to grow compact and strong. A plant short of light grows tall and thin and leans toward the window, which is a clear sign it needs more.

On a windowsill, turn the container every day or two so the plant grows straight. With a grow light, put it on a timer and keep the light and its cord away from the water.

Not too hot, not too cold

Most leafy plants like the same temperatures people do. Very hot spots, like a windowsill in strong summer sun, heat the water. Warm water holds less oxygen, and the roots can struggle. Very cold windows in winter slow growth. A bright spot in a comfortable room is best.

Healthy plant, struggling plant

A healthy plant has firm, green leaves and white or cream roots. Yellowing leaves can mean the plant needs more light or more nutrients. Brown, crispy leaf edges can point to a solution that is too strong, or to heat. Wilting can mean the roots cannot reach the water, or the water is too warm. Nutrients, pH and Safety has more detail.

Simple comparisons to try

Your journal becomes more useful if you compare. Grow the same plant in two containers, one in a sunny window and one in a shadier spot, or try two different light covers. Measure both each week. Change only one thing at a time, so you know what made the difference.

Almost ready

When the leaves are large and the plant looks full, harvest is close. See how to pick it in Step 6: Pick and enjoy.

Measure the same way each time

Measure from the top of the lid to the tip of the tallest leaf, at the same time of day, and write it down. Count the leaves too. After a few weeks, the numbers show you how your plant grew.

A week-by-week guide

• Week one: the seedling settles in, and new roots reach toward the water
• Week two: new leaves appear, and the water level starts to drop
• Week three and after: the plant grows faster and drinks more
• When the leaves are large and full: harvest time

Every plant and every home is a little different, so yours may be faster or slower.

Things to notice

Small changes show up every few days: a new leaf unfolding in the center, a thicker stem, roots turning from short and white to long and branched. Leaves often turn toward the light during the day. Writing these details down is what turns guesswork into experience.

Patience pays

Some days it will look as if nothing is happening. Then two new leaves appear overnight. Plants grow a little all the time, and your notes will show the growth you did not notice day to day.

Light hours

Leafy plants grow best with many hours of good light each day. A south-facing window is usually brightest in the northern hemisphere. If the days are short or the window is shaded, a grow light on a timer gives the plant a steady day length.

Keep notes simple

A grow journal does not need to be elaborate. A few lines in a notebook or a note on your phone, plus a weekly photo, is enough to spot patterns and remember what worked.

Signs of steady growth

New leaves appearing every few days, a thickening stem, firm leaves and white roots reaching the water all mean the plant is on track. Keep doing what you are doing.