Plugs, liners and potted plants: understanding plant sizes when you order by mail

Ordering & arrival · Published 2026-10-23

Three small fibre pots each holding a young seedling, carried on a wooden board in one hand — Small plants travel well and settle in fast. Photo: Daniel Hjalmarsson (Unsplash), via Wikimedia Commons, CC0.

The same perennial can be sold as a tiny plug, a quart pot or a three-gallon specimen, at prices that differ tenfold. None is wrong. Understanding what each size means, and what you will have to do with it, is the key to getting good value from mail-order plants.

The sizes, from smallest to largest

Size	What it is	Best for	Trade-offs
Plug	A young plant in a small tapered cell, sold in trays or packs	Mass plantings, ground covers, meadows, annual bedding	Needs growing on or careful planting and watering; slower to fill in
Liner	A rooted cutting or young plant in a small pot or deep cell	Shrubs, vines, perennials you are happy to grow on	Takes one or more seasons to reach garden size
Quart (about 1 litre)	A small potted plant	Most perennials, herbs	Good balance of price and size
1 gallon (trade size)	A larger potted plant	Perennials that flower the first year, small shrubs	Heavier, more expensive to ship
2–3 gallon and up	An established shrub or young tree	Instant effect, specimen plants	Costly shipping; can be root-bound

Nursery container sizes such as "#1" or "1 gallon" are trade classes rather than exact measured volumes, and pots of the same nominal size vary between growers. Pot size alone also says little about the plant: a recently potted-up plant may have a small root system in a big pot. Ask for the plant's height or age, and look for photos of what ships.

Which plants are worth buying small

Fast-growing perennials and grasses, which catch up with larger plants within a season.
Ground covers and meadow plants, where you need many plants and small ones are far cheaper per square foot.
Plants that dislike root disturbance, such as some taprooted natives, which often establish better when planted young.
Herbs and annuals, which grow quickly.

Slow growers, such as many shrubs, conifers and some perennials like peonies, are often worth buying larger, or bare-root at a good grade; see bare-root plants.

Comparing value

Divide the price, including a share of shipping, by the number of plants.
Estimate how long each size will take to reach the effect you want. A plug at a quarter of the price that takes an extra season may still be the better buy.
Consider your time: plugs and liners may need potting up, sheltering and watering before planting out.
Factor in losses: very small plants are more vulnerable in their first weeks.

Plugs and liners on arrival

Young plants are shipped in their cells or small pots, usually with the root ball wrapped or held in place. When they arrive:

Open the box the same day and remove the plants carefully, supporting the root ball.
Water if the mix is dry, letting it drain fully.
Place them in bright, indirect light for a day or two; plants that travelled in the dark can scorch in full sun.
Decide whether to plant out or pot on. Pot on if the weather is harsh, if the plants are very small, or if you are not ready.

Potting on

Move each plug into a pot one or two sizes larger, using a fresh, free-draining potting mix.
Set the plant at the same depth it was growing.
Keep pots in a sheltered spot outdoors in suitable weather, or under lights or in a cold frame if it is still cold.
Plant out when roots fill the new pot and conditions are right.

Planting out small plants

Water the plants in their cells an hour before planting.
Plant on a cool, cloudy day or in the evening.
Firm the soil gently around each plug so there are no air pockets.
Water thoroughly and mulch lightly, keeping mulch away from the stems.
Check daily for the first two weeks: small root balls dry out quickly.
Protect from slugs, rabbits and birds, which find young plants irresistible.

Larger potted plants

When a large potted plant arrives, check whether the roots are circling the pot. Gently tease circling roots outward before planting, or score the sides of a dense root ball. Plant at the same depth as in the pot, never deeper, and water deeply. Potting mix dries faster than garden soil, so water the root ball itself, not just the surrounding soil, for the first few weeks.

A word on packaging

Mail-order plants inevitably come with packaging: boxes, paper, plastic sleeves and sometimes pots. Reuse what you can: sturdy pots for potting on, paper as mulch under compost, boxes for storage. Some nurseries now use paper-based packing and compostable pots; it is a fair thing to ask about when choosing a supplier.

Ordering in quantity

For hedges, ground covers or meadows, plugs and liners sold in trays of dozens can cut the cost of a planting dramatically. Before ordering in quantity, count the plants you need from the spacing in the catalog, add a few spares for losses, and plan for planting over a short period: a tray of plugs that waits weeks in a garage will not do well. If the area is large, order in two batches and plant in two sessions. On rented land, check first whether the lease allows a new hedge or other permanent planting; see renting a house with a garden.

Small plants cost less and settle in fast, if you give them the first two weeks.

Sources

Purdue University Consumer Horticulture, Temporary shelter for bare-root landscape plants.
University of Vermont Extension, Seed starting basics (hardening off young plants).
Iowa State University Extension, Container vegetable gardening.