How Many Plants Are In A Flat

If you’re planning your garden, one of the most common questions is: how many plants are in a flat? This simple question is key to buying the right amount of plants and using your space efficiently. Understanding plant flat sizes will save you time, money, and prevent the headache of having too many or too few plants for your beds.

Nurseries grow and sell young plants in trays called flats. But there’s no single standard size. The count changes based on the plant type, its mature size, and the grower’s preferences. Knowing what to expect helps you plan like a pro.

Typically, a full flat holds 36, 48, or 72 plants. The most common size you’ll see is a 12-inch by 20-inch flat containing 48 individual cells. That’s often called a “48-plant flat” or a “standard flat.” However, many factors influence the final number.

Common Flat Sizes and Plant Counts

Here’s a breakdown of the flats you’ll likely encounter at your local garden center:

Standard 1020 Flat (with cells): This is the classic tray measuring 10 inches by 20 inches. It usually comes configured with 12, 18, 24, 36, 48, or 72 smaller plastic cells. The 48-cell version is extremely popular for annuals like petunias and marigolds.
Full Flat: Generally refers to a tray with 36 to 48 plants. It’s a substantial purchase, perfect for filling a large area.
Half Flat: As the name suggests, this is half of a full flat. You’ll often get 18 or 24 plants. It’s a great option for smaller gardens or trying out new varieties.
4-Pack / 6-Pack: These are small sections often torn from a larger flat. They contain 4 or 6 individual plants and are ideal for small projects.
Market Packs: These are sturdy, smaller trays often holding 4, 6, 8, or 9 plants. They are common for vegetable starters like tomatoes and peppers.

Why Plant Counts Vary So Much

The size of the plant at sale time dictates how many fit in a flat. A seedling that grows quickly needs more room from the start.

Vegetable Starts: Larger vegetables like tomatoes, broccoli, and peppers are often sold in market packs of 4, 6, or 9 because they need substantial root space early on.
Annual Flowers: Petunias, impatiens, and begonias are commonly sold in 48 or 72-cell flats because they are smaller when ready for sale.
Herbs and Ground Covers: These can be found in dense flats of 72 or even 128 “plugs” (very small seedlings).
Pint and Quart Containers: For more established perennials or large annuals, you’ll buy individual pots, not flats. These are not counted in a flat system.

How to Calculate Plants for Your Garden Space

Now that you know how many plants are in a flat, let’s apply it to your plan. Follow these steps to avoid overbuying.

Step 1: Measure Your Garden Bed

Get the length and width of your planting area in feet. Multiply them to get the total square footage. For a bed that is 10 feet long and 4 feet wide, you have 40 square feet to fill.

Step 2: Check Plant Spacing Requirements

Every plant tag or seed packet lists the “spacing” needed. This is the distance you should leave between each plant. For example, marigolds might need 8-10 inches apart, while cabbage needs 18-24 inches.

Step 3: Do the Simple Math

Let’s say you’re planting marigolds (10-inch spacing) in your 40 sq ft bed. Convert spacing to feet (10 inches is about 0.83 feet). A rough estimate is to divide the square footage by the spacing in feet squared. So, 40 / (0.83 x 0.83) ≈ 58 plants. Since marigolds often come in 48-cell flats, you’d need about one and a quarter flats.

A simpler method is to use an online plant spacing calculator. You just input your bed size and plant type, and it does the math for you.

Step 4: Always Buy a Few Extra

It’s smart to buy 5-10% more plants than your calculation. This accounts for any losses during transplanting or uneven growth. You can always use extras in containers.

Pro Tips for Buying and Handling Flats

Always Check Before You Buy: Count the cells in the flat. Don’t assume it’s 48; it could be 36 or 72. The price should reflect the count.
Look for Healthy Flats: Choose flats with uniform growth, green leaves, and no signs of disease or pests. Avoid trays with lots of dry or wilted plants.
Ask the Nursery: If your unsure, just ask a staff member. They can tell you the exact count and recommend how many you’ll need for your space.
Water Before Transplanting: Always water the flat thoroughly a few hours before you plant. This reduces shock and makes it easier to pop plants out of their cells.
Gently Remove Plants: Don’t yank them by the stem. Squeeze the bottom of the cell, turn it upside down, and let the plant slide into your hand.

Planning for Vegetables vs. Flowers

Your shopping strategy changes based on what you’re planting.

Vegetable Garden Planning

Vegetables need precise spacing for good air flow and yield. You’ll often buy fewer, larger plants.

Tomatoes & Peppers: Usually sold in 4-packs or 9-packs. You might only need one or two packs for a small family.
Lettuce & Greens: Can be bought in dense 72-cell flats and planted close together for a “cut-and-come-again” harvest.
Cucumbers & Squash: Often sold in 4-packs. Their vines spread widely, so you need fewer plants than you think.

Flower Bed Planning

For a lush, full look, annual flowers are often planted closer together than the tag suggests. Flats are perfect for this.

Mass Planting: For a big impact of one color, calculate using the tighter spacing (e.g., 6-8 inches for small annuals). You might need multiple full flats.
Mixing Varieties: Buy a few different half-flats or several 6-packs to create a mixed border without being overwhelmed by one type.

FAQ: Your Questions Answered

How many square feet does a flat of flowers cover?

It depends entirely on the plant spacing. A 48-cell flat of impatiens (spaced 10 inches apart) covers roughly 25-30 square feet. A flat of larger plants, like zinnias spaced 12 inches apart, covers more area.

What is the difference between a flat and a tray?

Often these terms are used interchangeably. But technically, the “flat” usually refers to the whole unit with the plants. The “tray” or “1020 tray” is the bottom plastic part that holds the individual cells or pots. Sometimes you buy “flats” without cells, just soil blocks.

How many plants in a flat of vinca or petunias?

Petunias and vinca (annual vinca) are almost always sold in 48-cell standard flats. Occasionally you might find them in 36-cell flats for larger starter plants, or in 72-cell “plug” flats for smaller starts.

Can I buy partial flats?

Many local nurseries will let you break a flat and buy only the number of plants you need. Big box stores usually require you to buy the pre-packaged whole flat or pack. It never hurts to ask!

How should I store flats before planting?

Keep them in a sheltered, shaded spot and water daily. Don’t let them sit in full sun or dry out. Try to plant them within a day or two of purchase for the best results. If you must wait longer, consider potting them up into slightly larger containers.

A Final Word on Garden Planning

Understanding the answer to “how many plants are in a flat” is a fundamental skill for efficient garden planning. It takes the guesswork out of shopping and helps you create a detailed, executable plan. Always start with your measurements, check those plant tags for spacing, and don’t be afraid to ask questions at the nursery.

With this knowledge, you can walk into the garden center with confidence, knowing exactly what you need to bring your garden vision to life. Remember, a little planning goes a long way toward creating a beautiful and productive space that you can enjoy all season long. Just be sure to account for a few extra plants, because its always tempting to add one more color.