The Complete Guide to Seeds, Bulbs and Seed Starting Kits

Where Every Garden Begins

A seed is a promise packed into a shell. A bulb is a season of colour compressed into a papery package no larger than your fist. Between the two of them, they contain everything a garden can become — flowers, food, fragrance, and the quiet satisfaction of watching something grow from almost nothing into something alive.

This guide covers three connected subjects. First, how to buy seeds — understanding the difference between heirloom and hybrid, what to look for in a good seed packet, and how to store seeds so they remain viable. Second, how to buy bulbs — recognising quality, understanding planting times, and choosing bulbs that naturalise and return for years. Third, the equipment that helps you start seeds indoors — trays, heat mats, grow lights, and the simple setups that give seedlings the best possible start before they move into the garden.

# Part One: Seeds {#part-one-seeds}

Understanding Seed Types

Walk into any garden centre or browse an online seed catalogue and you will encounter terms that can be confusing: open-pollinated, heirloom, F1 hybrid, organic. These are not marketing labels — they describe genuinely different things, and understanding the difference helps you choose seeds that match your gardening goals.

Open-Pollinated Seeds

Open-pollinated (OP) seeds come from plants that were pollinated naturally — by insects, wind, birds, or gravity — without human intervention controlling which parent plant contributed pollen. The offspring are genetically diverse but broadly "true to type," meaning the plants grown from saved seed will closely resemble the parent plant.

The key advantage: You can save seeds from open-pollinated plants and grow them again the following season. The saved seed will produce plants similar to the parent, allowing you to develop your own locally adapted strains over time. This is how humanity has grown food for thousands of years.

The trade-off: Open-pollinated varieties may be less uniform than hybrids — some variation in size, shape, and timing is normal. This is not a flaw; it is genetic diversity, and it is part of what makes OP varieties resilient.

Heirloom (Heritage) Seeds

Heirloom seeds are open-pollinated varieties that have been passed down through generations — typically at least 50 years, though definitions vary. They are valued for flavour, character, historical significance, and the genetic diversity they represent.

Why they matter: Heirloom varieties preserve genetic diversity that the modern seed industry has largely discarded. An heirloom tomato bred for flavour over a century ago carries genetic traits that no modern hybrid can replicate. Many heirloom vegetables are prized by chefs and home growers for flavour that commercial varieties, bred for shelf life and uniformity, cannot match.

The honest reality: Heirloom varieties are sometimes less productive, less disease-resistant, and less uniform than modern hybrids. An heirloom tomato may crack more easily, ripen unevenly, or produce fewer fruit than a hybrid. What it delivers in flavour and character compensates for what it lacks in perfection — but the trade-off exists.

F1 Hybrid Seeds

F1 (first filial generation) hybrid seeds are produced by deliberately cross-pollinating two specific parent varieties under controlled conditions. The resulting offspring combine desirable traits from both parents — often including increased vigour, higher yields, disease resistance, and uniform growth.

The advantages are real: F1 hybrids typically grow more vigorously, produce more uniformly, and resist specific diseases more effectively than either parent. For crops where reliable performance matters — where you need every plant to produce predictably — F1 hybrids are excellent.

The limitation is equally real: Seeds saved from F1 hybrid plants do not breed true. The second generation (F2) is genetically unstable — the plants may revert to traits of either grandparent, producing unpredictable results. If you grow F1 hybrids, you buy new seed each season. This is not a conspiracy; it is genetics. The hybrid vigour exists only in the first generation.

F1 hybrids are not genetically modified (GMO). They are produced through controlled pollination — the same biological process as natural pollination, just directed by human hands. No genes are artificially inserted or modified.

When to choose F1: When disease resistance matters (particularly for crops prone to specific diseases in your area). When uniform, predictable yields are important. When you are growing a crop for the first time and want to maximise your chances of success.

When to choose heirloom or OP: When flavour is the priority. When you want to save your own seed. When you value genetic diversity and want to contribute to preserving it. When you enjoy the character and variability that heritage varieties bring.

Or choose both. There is no obligation to pick a side. Many experienced gardeners grow F1 hybrids of some crops (disease-prone cucumbers, for example) and heirlooms of others (tomatoes grown primarily for flavour). The pragmatic approach is to match the seed type to the crop and the purpose.

Organic Seeds

Seeds produced from plants grown under certified organic conditions — without synthetic pesticides, herbicides, or fertilisers. The plants themselves and the seeds they produce have not been treated with chemical fungicides or coatings.

Organic seeds can be either open-pollinated or hybrid. The organic certification applies to how the parent plants were grown, not to the genetic type of the seed.

Does it matter? If you are growing an organic garden, starting with organic seed maintains organic integrity from the very beginning. If you are not certified organic, organic seeds still offer the benefit of being untreated — no chemical seed coatings that might concern you.

What About GMO?

Genetically modified organism (GMO) seeds have had their DNA altered in a laboratory by inserting genes from another organism. GMO seeds are not available to home gardeners through normal retail channels — they are used exclusively in commercial agriculture. You will not encounter GMO seeds in a garden centre or online seed catalogue.

If a seed packet says "non-GMO," this is technically true of every seed available to home gardeners. It is not a distinguishing feature; it is a marketing statement about something that was never a risk in the home garden context.

Buying Good Seed: What to Look For

Buy from reputable seed companies. Established seed suppliers test their seed for germination rates and genetic purity. The small seed companies that specialise in heritage and unusual varieties are often the best sources for interesting and high-quality seed. The cheapest seeds are not always the worst, and the most expensive are not always the best — but buying from a supplier who cares about their product makes a difference.

Check the packet for information. A good seed packet tells you the variety name, the sowing period, germination temperature, expected germination rate, days to maturity, planting depth, spacing, and light requirements. The more information on the packet, the more seriously the supplier takes their product.

Look for a "packed for" or "sell by" indication. Seed viability decreases with age. Fresh seed germinates at higher rates than old seed. A packet with no date may have been sitting in a warehouse or on a rack for years.

Seed count or weight matters. Some packets contain generous quantities; others contain remarkably few seeds for the price. Compare the seed count (or weight) per packet when evaluating value.

Seed Freshness and Viability

Not all seeds age at the same rate. Some remain viable for many years; others lose germination power quickly.

Long-lived seeds (4–6 or more seasons if stored well): Tomato, cucumber, melon, brassicas (cabbage, broccoli, kale), lettuce, radish, beetroot.

Shorter-lived seeds (1–3 seasons): Onion, leek, parsnip, sweetcorn, pepper, carrot. These benefit most from being sown fresh.

The practical advice: Buy parsnip, onion, and leek seed fresh each season. Longer-lived seeds can be stored and used over multiple seasons, saving money.

Storing Seeds Properly

Seeds are alive — dormant, but alive. They remain viable longest when stored cool, dry, and dark. Heat, moisture, and light all accelerate deterioration.

The best home storage: Seal unused seed packets in an airtight container (a jar with a tight lid, a zip-lock bag with the air pressed out) and store in a cool, dark place. A refrigerator is ideal — the consistently cool temperature extends viability significantly. Include a small sachet of silica gel to absorb residual moisture.

Do not freeze seeds unless they are completely dry. Moisture inside a seed expands when frozen and damages the embryo. Professionally dried seeds can be frozen; home-stored seeds are safer in the refrigerator.

Saving Your Own Seeds

If you grow open-pollinated or heirloom varieties, you can save seeds from your best plants to sow the following season. Over time, saved seeds adapt to your specific soil, climate, and growing conditions — producing plants that are genuinely locally adapted.

The basics: Allow the fruit or seedhead to mature fully on the plant. Harvest the seed, clean and dry it thoroughly, label it with the variety name and date, and store as described above.

The caution: Cross-pollination between varieties of the same species can produce unexpected results in saved seed. Tomatoes and beans are largely self-pollinating and relatively safe for beginners to save. Squash, sweetcorn, and brassicas cross-pollinate freely and require isolation to produce true-to-type saved seed.

Seeds from F1 hybrids should not be saved for replanting. The second generation will be genetically unpredictable.

# Part Two: Bulbs {#part-two-bulbs}

How Bulbs Work

A bulb is a complete plant compressed into a storage organ — a self-contained package of roots, stem, leaves, and flower bud surrounded by layers of stored food energy. When conditions are right (the correct temperature, moisture, and season), the bulb activates, sending roots downward and a shoot upward, drawing on its stored energy to fuel the initial growth until the leaves can take over and photosynthesize.

The term "bulb" in gardening is used loosely to include true bulbs (tulips, daffodils, lilies), corms (crocus, gladiolus), tubers (dahlias, begonias), and rhizomes (iris). Each has a slightly different structure, but for the purpose of buying and planting, they behave similarly.

The flower bud is already formed inside the bulb before you buy it. When you purchase a tulip bulb in autumn, the flower that will appear the following spring is already there in miniature, packed inside the bulb. This means the quality of the bulb at the point of purchase directly determines the quality of the flower. A small, soft, damaged bulb cannot produce a magnificent bloom — the potential was compromised before you planted it.

Hardy Bulbs (Autumn-Planted, Spring-Flowering)

Hardy bulbs are planted in autumn, spend winter in the ground, and flower in spring. They require a period of cold (typically six weeks or more at soil temperatures below 10°C / 50°F) to break dormancy and trigger flowering.

The classics: Tulips, daffodils (narcissus), crocuses, hyacinths, snowdrops, muscari (grape hyacinth), alliums, bluebells, and scilla.

When to plant: When autumn night temperatures drop consistently and the soil has cooled — typically from early autumn through to early winter, depending on your climate. Earlier planting gives roots more time to establish before the ground freezes.

Extending the display: Choose early, mid, and late-flowering varieties to create a succession of bloom from late winter through late spring. Snowdrops and early crocuses appear first; then daffodils and early tulips; then later tulips and alliums. With thoughtful selection, you can have bulbs in flower for three months or more.

Tender Bulbs (Spring-Planted, Summer-Flowering)

Tender bulbs are planted in spring after the last frost and flower through summer and into autumn. They cannot survive freezing temperatures in the ground and must either be treated as annuals or dug up and stored over winter.

The classics: Dahlias, gladiolus, begonias, cannas, crocosmia (hardy in milder climates), lilies (many are hardy, but some are tender), and caladiums.

When to plant: After the last frost, when the soil has warmed. Starting tender bulbs in pots indoors a few weeks before the last frost gives them a head start.

Buying Quality Bulbs

Size matters. Larger bulbs produce larger flowers and more vigorous plants. A bigger tulip bulb means a bigger tulip. When buying bulbs, the circumference measurement on the label tells you the bulb size — larger numbers indicate larger bulbs. Premium-grade bulbs cost more per bulb but deliver noticeably better results.

Firmness is the key indicator of health. A good bulb feels firm, heavy for its size, and solid when gently squeezed. Reject bulbs that are soft, spongy, shrivelled, or have visible mould, rot, or damage. The basal plate (the flat base where roots emerge) should be intact and firm.

The papery skin (tunic) should be present but is not critical. Some handling damage to the outer skin is cosmetically imperfect but does not affect the bulb's viability, provided the flesh underneath is firm and undamaged.

Buy early in the season. Bulbs displayed in warm shops for weeks lose moisture and vigour. Buy as soon as new stock arrives and plant promptly. If you must store bulbs before planting, keep them in a cool (10–15°C / 50–60°F), dry, well-ventilated place — never in a sealed plastic bag, where they will sweat and rot.

Planting Depth and Spacing

The general rule: plant a bulb at a depth two to three times the bulb's height. A tulip bulb 5 cm (2 in) tall goes into a hole 10–15 cm (4–6 in) deep. A crocus corm 2.5 cm (1 in) tall goes 5–7.5 cm (2–3 in) deep.

Pointy end up, roots down. If you cannot tell which end is up, plant the bulb on its side — it will find its way to the surface.

Drainage is essential. Bulbs sitting in waterlogged soil rot. If your soil is heavy clay, improve drainage by working in grit or compost before planting, or plant in containers with good drainage. See our Planters, Pots and Container Gardening Guide for container options.

Naturalising: Bulbs That Come Back and Spread

Some bulbs, once planted, return and multiply year after year, gradually spreading to form larger drifts. This is naturalising, and it is one of the most rewarding things bulbs do.

The best naturalisers: Daffodils (almost indestructible, multiply reliably, and are ignored by squirrels and deer). Crocuses. Snowdrops. Muscari. Bluebells. Species tulips (the smaller, wild-type tulips naturalise far better than large hybrid tulips, which tend to decline after a few seasons).

The key to naturalising success: After flowering, do not cut back the foliage until it has yellowed and died back naturally — typically four to six weeks after the flowers fade. The leaves are photosynthesising and recharging the bulb with energy for the following season. Cutting them back early robs the bulb of next season's flower.

Storing Tender Bulbs Over Winter

In climates where the ground freezes, tender bulbs (dahlias, gladiolus, begonias, cannas) must be dug up after the first frost blackens the foliage, dried gently, and stored in a cool, dry, frost-free place over winter.

The process: Lift the bulbs carefully with a fork. Remove excess soil (leave soil on dahlia clumps). Allow them to dry in a cool, shaded, well-ventilated space for a few days. Store in paper bags, open boxes, or trays with dry vermiculite, peat, or sawdust at 5–15°C (40–60°F). Check monthly for rot or mould and discard any affected bulbs.

# Part Three: Seed Starting Equipment {#part-three-equipment}

Why Start Seeds Indoors?

Starting seeds indoors gives you a head start on the growing season. Seeds sown indoors weeks before the last frost produce transplant-sized seedlings ready to go into the garden as soon as conditions allow. This is particularly valuable for crops with long growing seasons (tomatoes, peppers, aubergines) that would not have time to mature if sown directly outdoors in cooler climates.

Indoor sowing also gives you control over germination conditions — temperature, moisture, and light — that the unpredictable outdoors cannot guarantee. Germination rates are typically higher indoors than in open ground.

Seed Trays, Modules and Cell Inserts

Standard seed trays (the shallow, flat trays, typically 37 × 22 cm / 15 × 9 in) are used for sowing seeds broadcast across the surface of compost, then pricking out (transplanting) individual seedlings once they develop their first true leaves.

Module trays (cell inserts) divide the tray into individual cells — each cell holds one or a few seeds, producing an individual seedling with its own root ball. Available in various cell sizes: small cells (128 or 72 per tray) for initial sowing, larger cells (24 or 15 per tray) for growing on. Module trays eliminate the need for pricking out, reduce root disturbance at transplanting, and make the process cleaner and more efficient.

What to look for: Rigid, well-made trays that do not flex or crack when lifted full of wet compost. Drainage holes in every cell. Reusable trays (thicker plastic) are more cost-effective and environmentally sensible than flimsy single-use trays that crack after one season.

Soil Blockers

A soil blocker is a hand tool that compresses damp seed compost into free-standing blocks — no tray, no pot, no plastic. Seeds are sown directly into a small dimple in the top of each block. The blocks sit on a flat tray, and roots grow within the block until transplanting.

The advantages: No plastic pots or cell trays needed. Roots are naturally air-pruned at the block edges (similar to fabric grow bags), producing healthy, fibrous root systems. No transplant shock — the entire block goes into the ground. Environmentally the most sustainable option.

The learning curve: Soil blockers require the compost to be mixed to the correct moisture level — too dry and the blocks crumble; too wet and they slump. It takes a few batches to get the feel right, but once learned, the technique is fast and satisfying.

Propagators and Humidity Domes

A propagator is a seed tray with a transparent lid (dome) that creates a warm, humid microclimate for germination. The enclosed environment retains moisture, reduces the need for frequent watering, and maintains a more consistent temperature around the seeds.

Unheated propagators (a tray with a clear lid) rely on ambient warmth — a windowsill, a warm room, or a position above a radiator. Simple, inexpensive, and effective for many common seeds.

Heated propagators include an electric heating element in the base that maintains a consistent soil temperature regardless of the room temperature. Particularly valuable for heat-loving seeds (tomatoes, peppers, aubergines, chillies) that germinate significantly faster and more reliably in warm soil (20–25°C / 68–77°F).

Humidity domes (clear plastic lids that fit over standard seed trays) serve the same purpose as a propagator lid but are sold separately, allowing you to add the humidity function to trays you already own.

Remove the lid once seedlings emerge. Seedlings need air circulation to develop strong stems. Leaving the dome on after germination creates damp, still conditions that encourage damping off — a fungal disease that kills seedlings at the soil line.

Heat Mats

A heat mat is a thin, flat electric mat placed beneath seed trays to warm the soil from below. It provides the consistent bottom heat that many seeds need for optimal germination without heating the entire room.

Most effective for: Tomatoes, peppers, chillies, aubergines, and other warm-season crops that germinate slowly or poorly in cool soil.

What to look for: A thermostat-controlled mat that maintains a set temperature rather than simply running at full heat. Uncontrolled mats can overheat the soil, which is as harmful to seeds as cold soil. Waterproof construction for safety around damp trays.

A heat mat is not always necessary. Many common seeds (lettuce, brassicas, peas, beans, herbs) germinate perfectly well at room temperature. A heat mat is an investment that pays off primarily for warm-season crops started early in the season when ambient temperatures are still cool.

Grow Lights for Seedlings

The most common problem with indoor-started seedlings is insufficient light. Seedlings on a windowsill lean toward the glass, grow tall and spindly (leggy), and produce weak stems — all signs of inadequate light. Even a bright window provides far less light than full outdoor sun.

LED grow lights or shop lights positioned directly above seed trays solve this problem. Seedlings need 14–16 hours of light per day, positioned close to the tops of the plants — typically 5–10 cm (2–4 in) above the seedling tips.

What to look for: Full-spectrum LED lights (which provide the range of wavelengths plants need for healthy growth). Adjustable hanging height (so you can raise the lights as seedlings grow). A simple plug-in timer that turns the lights on and off automatically — consistent light timing produces the strongest seedlings.

For a detailed exploration of grow light technology, see our Plant Grow Lights Guide.

Seed Starting Kits: All-in-One Options

All-in-one seed starting kits bundle a tray, cell inserts, a humidity dome, and sometimes a small amount of seed compost or compressed peat/coir pellets into a single package. Some premium kits include a heat mat and grow light.

The advantage: Convenience. Everything you need arrives together, sized to fit. Good for beginners who do not yet know which individual components to choose.

The limitation: Kit components are sometimes lower quality than individually purchased equivalents. Trays may be thin, domes may not fit securely, and included compost pellets may not provide enough volume for growing seedlings beyond the initial germination stage. Evaluate the kit components against what you would buy individually.

The Seed Starting Compost Question

Seeds need a fine-textured, low-nutrient, moisture-retentive medium for germination. Standard multipurpose compost is too coarse and too nutrient-rich — large lumps interfere with tiny seedlings, and high fertiliser levels can inhibit germination and burn delicate new roots.

Use a dedicated seed compost — fine, consistent, and formulated for germination. See our Potting Soil, Compost and Growing Media Guide for a detailed breakdown.

For soil blockers: The compost needs to be blended specifically for block making — finer and more cohesive than standard seed compost, with enough structure to hold together as a free-standing block.

Putting It Together: A Simple Indoor Setup

You do not need a greenhouse or a sophisticated propagation system to start seeds successfully. A simple, affordable setup produces excellent results.

The minimum: A seed tray with cell inserts, seed compost, a clear humidity dome, and a warm, bright windowsill. This is enough to start herbs, lettuce, brassicas, and many flowers successfully.

The upgrade: Add a heat mat (for tomatoes, peppers, and chillies) and an LED grow light on a timer (for stronger, stockier seedlings). A wire shelving unit with lights mounted under each shelf turns a small corner of a room into a multi-level seed starting station that can produce hundreds of seedlings in a modest space.

The key principle: Warmth for germination, light for growing. Seeds need warmth and moisture to germinate (a propagator or heat mat provides this). Once seedlings emerge, they need strong, consistent light to grow compact and sturdy (a grow light provides this). These two needs are sequential — warmth first, then light.

Common Mistakes Buyers Make

Buying Seeds on Impulse Without a Plan

A dozen beautiful seed packets bought in a moment of enthusiasm can result in more seedlings than you have garden space for. Plan your garden layout first, then buy the seeds you need.

Ignoring Seed Freshness

Old seed germinates poorly or not at all. Check dates, buy from suppliers with fast stock turnover, and do not rely on seeds left over from several seasons ago for crops with short viability (onions, parsnips).

Choosing Bulbs by Picture Rather Than by Feel

The photograph on the packet shows the flower; the bulb in your hand determines whether you will ever see that flower. Feel the bulb. Firm and heavy means healthy. Soft and light means compromised.

Planting Bulbs Too Shallow

Shallow-planted bulbs are vulnerable to frost, drought, and being dug up by squirrels. Plant at two to three times the bulb's height for proper insulation and root development.

Leaving the Propagator Lid On Too Long

The lid creates humidity for germination. Once seedlings emerge, they need air circulation. Leaving the dome on produces weak, damp seedlings susceptible to fungal disease.

Starting Seeds Too Early

Seedlings started too early outgrow their indoor space before the weather allows transplanting, becoming leggy and stressed. Count backward from your last frost date to determine the correct sowing date for each crop.

Insufficient Light for Seedlings

A windowsill is rarely bright enough for strong seedling growth. Leggy, pale, leaning seedlings are the most common indoor seed starting problem, and the solution is better light — either a brighter position or supplemental grow lights.

Comparison Table: Seed Types

Pre-Purchase Checklist

For seeds:

• What are you growing, and how much garden space do you have? Plan before buying.
• Do you want to save seed for next season? If yes, choose open-pollinated or heirloom varieties.
• Is disease resistance important for your crops? If yes, consider F1 hybrids for susceptible species.
• Is the seed fresh? Check for a date or "packed for" indication.
• Does the packet provide full sowing instructions (depth, spacing, temperature, timing)?

For bulbs:

• Are you buying hardy (autumn-plant) or tender (spring-plant) bulbs?
• Are the bulbs firm, heavy, and undamaged?
• Have you checked the planting depth and spacing requirements?
• If planting in containers, do the pots have adequate drainage?
• For naturalising: have you chosen varieties known to return and multiply?

For seed starting equipment:

• What will you start? Warm-season crops (tomatoes, peppers) benefit from heat mats; cool-season crops (lettuce, brassicas) often germinate at room temperature.
• Do you have adequate light? If not, plan for a grow light.
• Are your trays rigid, reusable, and easy to clean?
• Have you sourced seed-starting compost (not multipurpose)?

Why Buying Through Amazon Makes Sense

Amazon's seed, bulb, and equipment range covers everything from individual seed packets to bulk bulb collections and complete seed starting setups. Product listings include variety information, seed counts, bulb circumference measurements, and equipment specifications.

Customer feedback is particularly valuable across this category. For seeds, reviews from growers who describe germination rates, plant performance, and true-to-type accuracy reveal far more than a packet photograph. For bulbs, reviews that include photographs of the actual flowers (compared to the catalogue image) confirm whether the variety delivers on its promise. For equipment, reviews describing durability across multiple seasons, real-world heat mat temperatures, and grow light performance at seedling level provide the practical insight product specifications cannot.

Amazon Marketplace Protections

When you purchase through Amazon, several consumer protections apply. Products sold directly by Amazon are covered by standard consumer rights legislation, including the right to return items within a specified period.

For products sold by third-party sellers on the Amazon Marketplace, the A-to-Z Guarantee provides additional protection. If an item does not arrive, arrives damaged, or is materially different from what was described, Amazon will investigate and, where appropriate, issue a refund.

Amazon Renewed products — professionally inspected and restored items — come with their own guarantee, providing confidence when purchasing pre-owned equipment at reduced prices.