A bed with too many seedlings may look vigorous for a few days. The consequences, though, are usually evident soon thereafter. Leaves shade one another. Stems grow tall and spindly. Airflow is reduced. Roots vie in the same small space for the same moisture and nutrients. To the novice in agriculture, plant spacing may seem the least of one’s concerns when sowing, watering, or weeding. Yet, spacing affects the first two, and influences weeding. Plant spacing is not about pretty beds but adequate growth and good crop use. When spacing is too dense, even the most diligent irrigation and the best soil may not produce optimal plants. By learning this skill early you save seeds, minimize errors in thinning, and reduce later problems.
The way to learn this skill is to think about spacing in physical terms, not as a vague concept. Choose one crop before you sow. Get a feeling for what its early growth really looks like in the first few weeks. Mark a small length of row with your finger or a tool, and place each seed singly. This may seem to take much longer than the usual broadcast, but this will give you control over the process. Try to practice with larger dry beans, peas, or other large seeds before smaller ones. Place the seeds on the soil at the intended distance without covering. Step back and have a look at the seeds. Then lean down and imagine the leaves spreading sideways from each. This helps correct a common beginner error, namely, planting for the size of the seed or sprout rather than the size of the mature plant.
Another common error is to sow extra seed and then “fix it later.” This causes you to feel hesitant during thinning, since every seedling may look very beautiful to you. Your bed is then one where many plants survive in a clump, where none has room to grow properly. The solution starts before seeds go into the ground. Work with shorter lengths of row. Place seeds with care. And realize that the proper spacing for most crops can look sparse on the day of sowing. A second common error is to space everything equally. Leafy crops, root crops, and climbing crops require different space allocations. A carrot plant requires a large space beneath the ground. A lettuce plant requires a large horizontal space. Beans may require a space for both row planting and staking. Once you are thinking about how plants grow rather than about the size of seeds, spacing becomes easier to estimate accurately.
When spacing is difficult to judge, practice using the method of comparison. Sow two very short sections of the same crop. Sow one more closely than the other, by eye. Check each patch over the next two weeks. Which one dries more quickly? Which one is easier to weed? Which one produces seedlings with sturdier shapes and more uniform color? This is quick to learn, since you can easily see the differences in actual plants. If you have a bed that’s already too densely spaced, thinning shouldn’t feel like an admission of failure. It’s an opportunity to correct. Pull the weakest or least properly positioned sprouts, and space the remaining ones. The thinner the seedlings the better, the easier the job gets. And earlier is better than later, because roots start to intertwine as the plants age.
All it takes is a few minutes a day to get a handle on planting distance. Fifteen minutes on any bed or tray is sufficient. Spend the first few minutes measuring and drawing small sections. Then, place seeds more slowly, checking distance every few, rather than waiting until the whole row is done. Finish by viewing your row from overhead and profile, making sure each has room for root spread and leaf spread and light. Repeat this every day. You’ll find your hands get steadier and your eye more accurate. You’re also less likely to want to fill up every nook and cranny simply because bare earth may look like a gap in your crop.
Eventually, sowing will feel more and more calculated, less and less random. Your beds will be more easily watered. It will be easier to identify and isolate trouble plants. Thinning, mulching, and staking won’t take on the urgency of rescue missions. Good spacing gives each plant an equal start, which is one of the most practical kinds of horticultural care. And while it’s easy to dismiss this practice as unimportant, it determines the quality of everything that follows.