You can always spot a gardener by the dirt under the fingernails in spring and the garden catalogues scattered around the house in winter.

When the ground is frozen over, a garden exists entirely in our imagination, free of weeds and bugs, rabbits and nematodes. We spend evenings before the fireplace dreaming of English gardens, fields of chili peppers, re-landscaped alleys, naturalized hillsides and rock gardens brimming over with calculated naturalness.

Garden catalogues can become an obsession. Our search one year for arugala and sorrel seeds led us into a new world of garden fantasies, spurred initially by the Applewood Seed Co. catalogue. It advertised both herb and wildflower seeds with exotic names such as Bleeding Heart, Wild Blue Iris, Johnny Jump-Up and Edelweiss.

For $1, you get a packet of anywhere from 40 seeds (of cactus mix) to 600 seeds (of fleabane, otherwise known as daisy aspen). Three dollars buys you 1 ounce (or 14,000) wild poppy seeds. For $54, you can order a pound (or 980,00) black-eyed Susan seeds. Three pounds per acre is recommended for mass plantings.

An ounce of wildflower mix for moist areas costs $5.50 and includes 25,000 seeds: Baby Blue Eyes, Columbine, Coreopsis, Dame's Rocket, Larkspur, Ox-eye Daisy, Scarlet Flax, Wallflowers--enough to cover 750 square feet. (For more details, write Applewood Seed Co., P.O. Box 4000, Golden, Colo. 80401.)

Unless otherwise indicated, catalogues mentioned here are free. But these nurseries, often small Mom-and-Pop concerns, operate on a low-profit margin, so don't load up on freebies if you aren't a potential customer.

Wildflowers

Wildflowers can be planted in the home garden, but keep in mind the flower's natural habitat when choosing a site. Among firms that specialize in them, and have catalogues available: Gardens of the Blue Ridge (P.O. Box 10, Pineola, N.C. 28662)--Ships live wildflower plants (a minimum of 5 each) at very reasonable prices. For example, 80 cents for trillium.

Griffey's Nursery (Rte. 3, Box 28, Marshall, N.C. 28753)--Prices as low as 25 cents for honeysuckle.

Illini Gardens, formerly Lounsberry Gardens (P.O. Box 125, Oakford, Ill. 62673)--Catalogue descriptions fuller than most.

Kester's Wild Game Food Nurseries (P.O. Box V, Omro, Wis. 54963) Catalogue, $1. Sells aquatic plants, dry seeds, roots and bulbs for wildlife plantings designed to attract and feed migratory birds, upland game birds and other wildlife.

Lamb Nurseries (E. 101 Sharp Ave., Spokane, Wash. 99202)--Hardy perennials (including many chrysanthemums, violas and painted daisies), rockplants, shrubs and vines.

Putney Nursery (Putney, Vt. 05346)--A reliable firm that advises ordering before April for spring shipping, but prefers fall shipping when plants are dormant.

Rakestraw's (G-3094 S. Term St., Burton Mich. 48529)--Catalogue, $1. Specializes in sedums, sempervivums (hens and chicks) and other perennials for the rock garden, as well as alpines and dwarf evergreens for the bonsai gardener.

Special Interest Items

Among specialized vendors for budding interests:

Abbey Garden (4620 Carpinteria Ave., Carpinteria, Calif. 93013)--Catalogue, $1. Fifteen hundred species of cacti and succulents, many of them rare.

Bountiful Ridge Nurseries (Princess Anne, Md. 21853)--Fruit trees, berries and miniature roses.

Carroll Gardens (P.O. Box 310, 444 East Mail, Westminster, Md. 21157)--A fat catalogue of live plants and bulbs, especially perennials and herbs, many of them hard to find.

DeGiorgi Co., Inc., P.O. Box 413, Council Bluffs, Iowa 51502--Catalogue, 65 cents. Interesting vegetable and flower seeds, Italian varieties a specialty.

J.A. Demonchaux Co., 827 N. Kansas, Topeka, Kans. 66608. Imported French garden seeds.

D.S. George Nurseries, 2491 Penfield Rd. Fairport, N.Y. l4450--Clematis vines, $3.75.

Graham Seed Directory--$1 pamphlet, available from Frank Porter Graham Demonstration Farm and Training Center, Rte. 3, Box 95, Wadesboro, N.C. 28170. Not a catalogue but a gardener's guide to sources of traditional, old-time vegetable, fruit and nut varieties.

Greer Gardens, 1280 Goodpasture Island Rd., Eugene, Ore. 97401--Catalogue, $2, rhododendrons, azaleas and bonsai materials.

Lehman Gardens, 420-10th St., SW, Faribault, Minn. 55021--Some 125 varieties of chrysanthemums.

Henry Leuthardt Nurseries, Montauk Hwy., East Moriches, L.I., N.Y. 11940--Catalogue, $1. Fruit trees suited for Espalier plantings.

Lilypons Water Gardens, Lilypons Road, Lilypons, Md. 21717--Catalogue, $2. Water lilies, lotuses, goldfish and other garden-pool goodies.

Logee's Greenhouses, 55 North St., Danielson, Conn. 06239--Catalogue, $2.50. Large collection of begonias, plus scented geraniums and exotic indoor plants.

Nichols Garden Nursery, 1190 N. Pacific Hwy., Albany, Ore. 97321--Gourmet vegetable seeds from all over.

Roses of Yesterday and Today, 802 Brown's Valley Rd., Watsonville, Calif. 95076--Catalogue, $1.50. Old, rare and unusual roses.

Ed Storms, Inc., PO Box 775, Azle, Tex. 67020--Catalogue, $1. Lithops and other mesembs (South African succulents) and some of the most exotic plants around.

Waynesboro Nurseries, P.O. Box 987, Waynesboro, Va. 22980, and Louis Gerardi Nursery, Rte. 1, Box 143, O'Fallon, Ill. 62269--Common and uncommon fruit and nut trees (including American chestnut and persimmon).

Wayside Gardens, Hodges, S.C. 29695--Catalogue, $2. Does for perennials--notably a "raspberry ice estate peony"--what Bloomie's catalogues do for underwear: move consumerism into the realm of expensive fantasy.

Gilbert H. Wild & Son, Inc., Sarcoxie, MO 64862--Catalogue, $2. Peonies, iris, and daylilies in abundance.