One of the earliest challenges a new gardener faces is determining which plants should be direct seeded and which should be started indoors, then transplanted. This decision can determine the success of a garden. When considering factors such as root sensitivity, growing seasons, and soil temperatures,there are general guidelines. The rules can be flexible depending on the plant, climate, and individual preferences. Below is an in-depth look at these two planting methods, with recommendations for common types of plants.
What is Direct Seeding?
Direct seeding is planting seeds straight into the spot in the garden soil where they will grow to maturity. This method is generally preferred for plants that have sensitive root systems or that grow quickly, such as beans, peas, and many root crops. The process eliminates the need to move seedlings later, reducing the risk of transplant shock. Direct seeding also works well in regions with long growing seasons and warm soil temperatures, which allow seeds to germinate and grow without needing extra protection or care.
However, direct seeding does come with some challenges. Seeds sown directly in the garden may be more vulnerable to pests, uneven moisture levels, and temperature fluctuations. In climates where the growing season is short or unpredictable, certain plants may not reach maturity in time if they are direct-seeded too late.
What is Transplanting?
Transplanting, on the other hand, involves starting seeds in trays or containers, often indoors or in a controlled environment. Once the seedlings reach a certain size, they are moved—or transplanted—into the garden. This method is useful for plants that need a longer growing season, require specific soil temperatures for germination, or are particularly delicate in their early stages. Starting seeds indoors also allows gardeners to begin growing before outdoor conditions are ideal, making it a popular choice in regions with cold springs or short summers.
Transplanting can give plants a head start, enabling them to establish strong root systems before facing the challenges of outdoor growth. However, it’s important to time the transplant carefully to avoid disturbing the plant’s roots too much, as this can cause stress and will stunt growth. In addition, hardening off seedlings—gradually exposing them to outdoor conditions before planting them in the garden—is crucial to ensure their successful adaptation.
Root Crops: Direct Seeding vs. Transplanting
Root crops typically have delicate root systems, which makes direct seeding the preferred method for many of them. These plants develop their edible parts underground, so any disturbance to their roots can impact their growth and final yield.
Potatoes, Sweet Potatoes, and Garlic
These crops are typically propagated from pieces of the plant itself rather than seeds. Potatoes are planted from "seed potatoes," which are pieces of potato with at least one growth eye, and sweet potatoes require slips—vine-like shoots that sprout from the root. Garlic is planted from individual cloves, each of which grows into a full bulb. Since these plants grow from parts of the plant rather than seeds, they are best suited to direct seeding. Attempting to transplant them after they begin growing can damage their root systems, and cause the crop to fail.
Carrots, Radishes, and Turnips
These common root crops are also best direct-seeded. Carrots, in particular, are known for their sensitivity to root disturbance, and transplanting them often results in stunted growth or malformed roots. While radishes and turnips are slightly more tolerant of root disturbance, they still perform best when directly seeded into the garden.
Onions
Onions are unique among root crops in that they can be grown from both seed starts (immature seedlings) and sets (small, immature bulbs). Although they can be direct-seeded, onions are commonly started in trays and then transplanted into the garden. Their root systems are resilient enough to handle transplanting, which gives them an advantage in cooler climates where the growing season might not be long enough for direct seeding to be effective. The ability to start onions early and then transplant them once the soil warms up is key to ensuring a strong yield.
Fruiting Crops: Transplanting for Success
Fruiting crops—such as tomatoes, peppers, and eggplants—benefit greatly from transplanting, primarily due to their long growing seasons. Many of these crops take months to mature and require consistently warm soil and air temperatures to thrive. In regions with cooler climates or short summers, direct seeding fruiting crops can delay the start of their growth, making it difficult for them to produce fruit before the end of the growing season.
Tomatoes, Peppers, and Eggplants
These plants are often started indoors 6-8 weeks before the last expected frost. Transplanting helps them develop strong roots and early growth in controlled conditions before they face the stress of outdoor weather. By the time they are transplanted, the soil and air temperatures are warm enough to support growth, giving them the time needed to mature and produce fruit. Additionally, transplanting minimizes the risk of frost damage, a common threat in colder regions.
Cucumbers, Squash, and Melons
While cucumbers, squash, and melons can be transplanted, they generally prefer to be direct-seeded. These crops have sensitive root systems that do not handle transplanting well, especially once they have developed a robust root structure. However, in regions with shorter growing seasons, starting them in large pots and transplanting them once the soil has warmed can help ensure they have enough time to mature. Melons, in particular, are more sensitive to transplanting than cucumbers and squash, and they thrive in warm temperatures, so care must be taken to minimize root disturbance.
Beans, Peas, and Corn: Direct Seeding is Best
These crops are typically direct-seeded due to their sensitive root systems and fast-growing nature. However, corn presents a few unique challenges.
Corn
Corn requires a relatively long growing season of 90-100 days, depending on the variety. It also needs warm soil temperatures of 60°F or higher to germinate effectively. Direct seeding is ideal because corn grows quickly once the soil warms. In regions with short growing seasons, corn must be planted as soon as possible after the last frost to ensure it has time to mature before the first fall frost.
For gardeners facing pest pressure or unfavorable early-season conditions, there is an alternative approach: corn can be started in biodegradable containers, such as toilet paper rolls or peat moss pellets. These containers can be planted directly into the garden without disturbing the roots, offering a way to start corn early without risking transplant shock. However, this method is only recommended when direct seeding is not possible, as corn prefers to be sown directly in the soil.
Leafy Greens: Flexible in Both Methods
Leafy greens, including lettuce, spinach, kale, broccoli, and cauliflower, are among the most adaptable crops when it comes to direct seeding and transplanting. These plants can be grown using either method, depending on the gardener’s preference and the local climate.
Direct Seeding
When direct-seeded, leafy greens grow quickly, often producing a harvest within 40-60 days. This makes them ideal for gardeners who want a fast-growing crop that doesn’t require much fuss. However, direct seeding can lead to overcrowding, as many greens grow in dense clusters. Thinning out the plants to ensure they have enough space is critical for achieving large, healthy leaves or heads.
Transplanting
Transplanting leafy greens allows for more controlled spacing and gives the plants a head start, especially in cooler climates or when the soil is too cold for seeds to germinate. Transplanting also helps avoid early-season pests, which often target young seedlings. By starting greens in trays, gardeners can protect the plants from slugs, snails, and other pests that might decimate them if directly seeded.
In climates where temperatures fluctuate or warm up too quickly, transplanting can also be beneficial, as it allows greens to mature before the summer heat sets in. This rapid temperature climb can cause many leafy greens to bolt (flower prematurely) and become bitter.
Root Sensitivity, Growing Seasons, and Soil Temperatures
One of the most critical factors in deciding whether to direct seed or transplant is root sensitivity. Plants with delicate root systems, such as carrots and melons, generally fare better when direct-seeded. In contrast, plants with more robust root systems, like onions and tomatoes, can handle transplanting with minimal risk.
Growing season length is another important consideration. In regions with shorter summers or unpredictable, volatile weather, transplanting can give plants a much-needed head start. Fruiting crops, which often require several months to mature, benefit most from transplanting, as they need to establish themselves before outdoor temperatures are consistently warm enough to support their growth.
Finally, soil temperature plays a vital role in germination and growth. Many crops, including corn, melons, and tomatoes, need warm soil to germinate and grow well. In cooler climates, transplanting can help mitigate the impact of cold soil early in the season. Starting seeds in trays ensures that plants are ready to go into the garden as soon as soil temperatures are warm enough to support healthy growth.