What Are True Leaves?

The small, oval leaf below the true leaves is the tomato cotyledon.

The small, oval leaf below the true leaves is the tomato cotyledon.

If you start seeds indoors, you've probably read the phrase, "when the seedling has a set of true leaves...." or something to that effect. What are true leaves?

When a seed germinates, it bursts out of its seed coat and sends up a stem. Some of these stems have one leaf (called a monocot) others have two leaves on it (called a dicot). Tomatoes, for example, are dicots, while corn is a monocot. Cotyledons are part of the seed and, on many plants, they provide photosynthesis as the plant grows. A bit later, a plant will form its first "true leaves." These leaves have the appearance and function that all future leaves will have, and they may look dramatically different than the cotyledons.

For seed starters, it's important to remember not to transplant seedlings until they have some true leaves. Here's a short video from the University of Illinois Extension Service on the difference between ctyledons and true leaves.

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10 Comments

  1. […] else the plants need to sprout. So avoid fertilizing the seedlings for around 1-2 weeks until the first pair of true leaves appear. At this moment, you need to transplant your cilantro into a larger pot with a good quality potting […]

  2. […] Minnesota State Horticultural Society emphasizes never to transplant your seedlings until they have developed true leaves. This is the […]

  3. […] What are true leaves and how do you know that your basil seedlings have grown one? After a few days after planting your basil seed, seed leaves will sprout from the cotyledons of the seedlings. Once the root establishes itself in the soil, only then will the second set of leaves or the “true leaves” emerge. […]

  4. […] tomatoes will soon develop their first true leaves. These look a little different than the cotyledons that first […]

  5. […] A seed tray is an essential container for sowing your seeds, but you’ll also need to find suitable containers for transplanting each small seedling into once it has its true leaves. […]

  6. […] A seed tray is an essential container for sowing your seeds, but you’ll also need to find suitable containers for transplanting each small seedling into once it has its true leaves. […]

  7. […] A seed tray is an essential container for sowing your seeds, but you’ll also need to find suitable containers for transplanting each small seedling once it has its true leaves. […]

  8. […] identifying unknown Chillies. I will wait for them to germinate, and then develop their first set of true leaves. From there, I will try to identify what species they are from based on the leaves […]

  9. […] seeds germinate and plants grow to several inches tall and have two sets of true leaves, thin the kohlrabi plants so they’re spaced 3-8 inches apart. You can transplant the thinnings to […]

  10. […] Not only do these crops grow quickly, many of them are easy to grow in containers or even indoors. Leafy greens and root vegetables tolerate some shade, too.In northern climates, more sun is generally better for a faster harvest. In hot areas, afternoon shade can help keep plants from bolting to seed.Sprouts and microgreens are the fastest vegetables to grow. Though the harvest volume is small, they are a great addition to salads and stir fries. Mung bean sprouts are ready in about 3-4 days.Microgreens are ready to harvest 14 to 21 days after planting, depending on the type of green. Some of the fastest growing microgreens may be ready in a week. Radishes, wheatgrass, corn shoots, cabbage, broccoli, and sunflower seeds are some of the quickest growers.Harvest microgreens when the plants get their first true leaves.   […]

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