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On paper, leeks and garlic should grow well together, but in a no-dig garden, particularly on small plots where space is at a premium, there are better ways to use every inch of your soil than inter-planting competing species.
This article is deliberately nuanced, as there is no reason you can’t grow leeks and garlic together, but equally, not many reasons why you should grow leeks and garlic together. As we go on we’ll talk about the potential benefits and the potential pitfalls in growing these two half-hardy alliums together.
Can you grow leeks and garlic together?
You can definitely plant leeks and garlic together without any harm to either vegetable, but like all gardening questions, there are pros and cons to either argument.
The main argument for why not to plant leeks and garlic together is to save space. Leeks and garlic should be planted 30cm apart, and should not be inter-planted if you plant them together. Leeks can be planted closely with fruit bushes and strawberries, while garlic makes excellent close quarter companions for carrots.
However, if you have a well-prepared bed, and are at the stage of crop rotation between legumes (beans and peas) and solanums (potatoes and tomatoes) then alliums (garlic and leeks) make excellent bed partners to help prepare the soil for potatoes.
Pros and cons of growing leeks and garlic together
Because there is no set rule for planting leeks and garlic together, we thought it made sense to pit the pros and cons of growing leeks and garlic together against each other. They are evenly weighted, but some considerations may be more important to you than others:
|Rotation||Leek and garlic share the same rotation and can both be grown after beans or peas, and before potatoes or outdoor tomatoes in a typical crop rotation.||Alliums are a useful break in crop rotation, so can be split up into different beds to provide a break between roots and brassicas. You are limiting rotations by grouping them together.|
|Conditions||Leeks and garlic both like well-drained, slightly acidic soil, rich in organic matter. This makes soil preparation easier.||N/A|
|Use of space||Leeks and garlic should both be spaced 1ft. apart, so grow well in neat parallel rows.||There are more efficient companion plants that could fill the gaps between garlic rows, making more of small gardens.|
|Watering & care||Leeks and garlic both need watering every 7-10 days.||You should stop watering garlic 2-3 weeks before harvest (continuing to water leeks can limit garlic storage options).|
|Harvesting||N/A||Leeks and garlic can be harvested all year round, while garlic should be harvested before early fall. This leaves gaps in the beds and makes cultivation difficult.|
|Pests||Onion fly (Delia Antiqua) is a common pest on onions and leeks but is much less damaging to garlic. Planting leeks and garlic together can confuse onion flies and reduce maggot damage to both.||Leeks and garlic share many of the same pests, so if you have problems with slugs they are more likely to attack garlic if it is planted with leeks. Thrips can also be exacerbated by planting alliums in groups.|
How to grow leeks and garlic together
All alliums are slightly different from one another, with big differences in sowing times between garlic and scallions, and the differences in spotting a harvestable onion, from a leek that’s ready for eating.
Leeks and garlic share many of the same traits:
- Leeks and garlic like the same soil
- Leeks and garlic like the same conditions
- Leeks and garlic attract the same pests
- Leeks and garlic grow at the roughly same depth
Because leeks and garlic have similar growing requirements it seems like a win-win to grow them together. They enjoy the same soil conditions (good drainage, slightly acidic, and loose enough to freely expand underground).
Their similarities come with mixed blessings too. For example, leeks and garlic both attract onion flies, but garlic is relatively unaffected by it, so it can be useful to distract the flies from leeks. On the other hand, both attract thrips and if your garden is already prone to thrips, it will be positively overrun by late summer if you grow leeks and garlic in the same bed.
Spacing leeks and garlic
Because leeks and garlic grow at roughly the same depth, they use the same nutrients in the bed, which means they should be strictly planted at 30cm apart, instead of in dense rows as we would usually expect companion planting to be done.
Companion plants for leeks and garlic
If you decide that you don’t have enough space to grow leeks and garlic together, then there are some brilliant companion planting options for both.
Garlic grows incredibly well with carrots. They can be planted in tightly packed beds as carrots take nutrients from deeper in the soil. In fact, garlic actually encourages carrots to search deeper for nutrients, and therefore grow longer, as well as confusing carrot fly.
Leeks grow very well alongside strawberries, and it’s often suggested that they help improve the flavour of the small soft fruits. Garlic, on the other hand, tends to leave a garlicky odour on everything it’s near, so should be kept well away from strawberries and soft fruit.
Common problems when growing leeks and garlic together
If you plan on storing garlic after harvest, it should not be grown with leeks. Like onions, garlic needs to be harvested at just the right time. When it comes to harvesting garlic you should stop watering around 2 weeks before harvest to help their skins dry out. If they are sharing a bed with leeks that require regular water during that period, they won’t store properly.
Leeks and garlic both overwinter well down to Zone 5 and milder parts of Zone 6 as long as the ground temperature doesn’t drop below -12°C/10.4°F. Both can be started indoors, or bought as young plants in early spring, making them easy to get started in a shared bed.
The most common problem with leek and garlic comes with their varied harvesting times. Leeks can be harvested as young tender plants in early summer, right through to mature, overwintered plants in late winter before they start growing again in their second year.
Final thoughts on growing leeks and garlic together
Personally, I won’t be pairing these two vegetables up any time soon, because I love to experiment with how tightly packed vegetable beds can be and thanks to an overwhelming annual influx of carrot fly, I rely on garlic to keep them away from my carrots, so for now at least, I won’t be planting garlic and leek together.
But don’t let me put you off. There is no reason in science or common sense that should stop you from planting these two alliums together. They will grow happily alongside each other, and make your life a lot easier when preparing your soil.